When we think of anxiety, we typically think of it as a psychological condition — and often it is. Generalized anxiety disorder, panic disorder, social anxiety, and other anxiety disorders are real conditions that benefit from therapy, lifestyle changes, and sometimes medication. But the body and mind are deeply connected, and sometimes what feels like anxiety is actually the body’s response to a physical imbalance.

Thyroid dysfunction, blood sugar abnormalities, nutritional deficiencies, hormonal imbalances, and other medical conditions can produce symptoms indistinguishable from primary anxiety disorders. Treating these underlying causes can dramatically improve or even eliminate anxiety symptoms — sometimes in people who have struggled for years without understanding the root cause.

This article explores the medical conditions that can cause or worsen anxiety, how to recognize when a physical cause might be involved, and what blood tests can reveal about the factors driving your symptoms.

Understanding Anxiety Symptoms

Anxiety manifests through a combination of psychological, physical, and behavioral symptoms. Understanding these symptoms is important because many of them — particularly the physical ones — can also result from medical conditions. When someone describes “anxiety,” they might be experiencing anything from persistent worry to full-blown panic attacks, and the specific symptom pattern provides important diagnostic clues.

Psychological symptoms:

• Excessive worry that’s difficult to control — worrying about many different things, often out of proportion to the actual situation
• Feeling nervous, restless, or on edge — a constant sense of tension or being keyed up
• Sense of impending danger, panic, or doom — feeling that something bad is about to happen even without evidence
• Difficulty concentrating or mind going blank — inability to focus, thoughts jumping around or disappearing entirely
• Irritability — being easily frustrated or annoyed, often surprising to the person experiencing it
• Fear of losing control or “going crazy”
• Feeling detached from oneself or surroundings (derealization/depersonalization) — a strange sense that you or the world isn’t real
• Anticipatory anxiety — dreading future events or situations
• Racing thoughts — mind moving too fast to keep up with

Physical symptoms:

• Rapid heartbeat (tachycardia) or palpitations — feeling the heart race, pound, or skip beats
• Shortness of breath or feeling of suffocation — like you can’t get enough air
• Chest tightness, pressure, or pain — often mistaken for heart problems
• Sweating — particularly palms, underarms, and forehead, even without exertion or heat
• Trembling or shaking — visible tremor in hands or internal sense of shaking
• Dizziness or lightheadedness — feeling unsteady or like you might faint
• Nausea, stomach upset, or “butterflies” — the gut-brain connection is powerful
• Hot flashes or chills — sudden waves of heat or cold
• Numbness or tingling sensations — often in hands, feet, or around the mouth
• Muscle tension — particularly in neck, shoulders, and jaw; may cause headaches
• Fatigue — anxiety is exhausting; the constant activation depletes energy
• Sleep disturbances — difficulty falling asleep, staying asleep, or restless unsatisfying sleep
• Dry mouth
• Frequent urination — the “nervous bladder” phenomenon
• Difficulty swallowing or lump in throat sensation

Behavioral symptoms:

• Avoidance of anxiety-provoking situations — steering clear of places, people, or activities that trigger anxiety
• Restlessness, inability to sit still — pacing, fidgeting, needing to move
• Compulsive behaviors to reduce anxiety — checking, reassurance-seeking, rituals
• Social withdrawal — avoiding people, canceling plans
• Procrastination — avoiding tasks that trigger anxiety
• Substance use — using alcohol, cannabis, or other substances to cope

Notice how many of the physical symptoms overlap with symptoms of medical conditions. A racing heart could be anxiety — or it could be hyperthyroidism, anemia, or an arrhythmia. Dizziness could be panic — or it could be low blood sugar, dehydration, or inner ear problems. Fatigue and difficulty concentrating could be generalized anxiety — or they could be hypothyroidism, anemia, or vitamin B12 deficiency. Tremor could be anxiety — or it could be excess thyroid hormone or medication effects.

This overlap is precisely why medical evaluation is important. Treating someone for an anxiety disorder when the underlying cause is hyperthyroidism not only fails to address the real problem — it allows a potentially serious medical condition to go untreated.

Types of anxiety presentations:

Understanding how anxiety presents helps identify when medical causes should be considered:

Generalized Anxiety Disorder (GAD): Persistent, excessive worry about many different things — health, money, family, work, world events — more days than not for at least six months. The worry is difficult to control and causes significant distress. Physical symptoms like muscle tension, fatigue, and sleep problems are common.

Panic Disorder: Recurrent unexpected panic attacks — sudden surges of intense fear or discomfort reaching peak intensity within minutes. Attacks include physical symptoms (pounding heart, sweating, trembling, shortness of breath, chest pain) and psychological symptoms (fear of dying, losing control, or going crazy). People with panic disorder often worry about having more attacks and may avoid places where attacks have occurred.

Social Anxiety Disorder: Intense fear of social situations where one might be judged, embarrassed, or humiliated. Physical symptoms like blushing, trembling, sweating, and nausea are common in feared situations.

Specific Phobias: Intense fear of specific objects or situations (heights, flying, needles, animals, etc.) that is out of proportion to actual danger.

Health Anxiety: Excessive worry about having or developing a serious illness, often with hyperawareness of body sensations and frequent checking behaviors or doctor visits.

When to consider a medical cause:

While anxiety disorders can occur at any age and in anyone, certain patterns suggest a medical cause may be contributing:

• New-onset anxiety without clear psychological trigger: Anxiety that appears suddenly, without major life stressors, trauma, or changes, warrants medical evaluation. Primary anxiety disorders typically have identifiable triggers or have been present for years.
• Anxiety starting later in life: While anxiety disorders typically begin in childhood, adolescence, or early adulthood, new anxiety after age 35-40 is statistically more likely to have a medical component. This doesn’t mean older adults can’t develop primary anxiety, but medical causes should be considered.
• Physical symptoms predominating: When physical symptoms (heart racing, tremor, sweating, weight changes, temperature intolerance) are more prominent than psychological worry, a physical cause becomes more likely.
• Anxiety not responding to standard treatments: If therapy (particularly cognitive behavioral therapy, which is highly effective for anxiety) and/or appropriate medications aren’t helping as expected, an underlying medical condition may be perpetuating symptoms.
• Anxiety accompanied by other physical symptoms: Unintentional weight changes, heat or cold intolerance, menstrual irregularities, hair changes, skin changes, or other systemic symptoms alongside anxiety suggest a medical cause.
• Family history of thyroid disease or autoimmune conditions: These conditions run in families and commonly cause anxiety. If relatives have thyroid problems, your risk is higher.
• Anxiety symptoms related to eating patterns: Symptoms that consistently occur when meals are skipped or a few hours after eating suggest blood sugar involvement.
• Anxiety with significant fatigue: While anxiety can cause fatigue from the constant activation and poor sleep, profound exhaustion alongside anxiety suggests conditions like thyroid dysfunction, anemia, or B12 deficiency.
• Panic-like episodes without psychological fear: If you experience physical symptoms of panic (racing heart, sweating, trembling) without the psychological component (fear, sense of doom), a medical cause is more likely.

The importance of ruling out medical causes:

Identifying a medical cause of anxiety matters for several important reasons:

• Treatment of the underlying condition often resolves anxiety symptoms — sometimes completely and often dramatically
• Some conditions causing anxiety (like hyperthyroidism) have serious health consequences if left untreated, including heart problems and bone loss
• Standard anxiety treatments may be less effective if a medical cause is driving symptoms — you can’t “think your way out of” hyperthyroidism
• Understanding the cause reduces self-blame and provides a clear path forward — it’s not a character flaw or weakness if your anxiety is being driven by a thyroid condition
• Medical causes are often very treatable once identified

Thyroid Dysfunction: A Major Medical Cause of Anxiety

Thyroid disorders are among the most common — and most overlooked — medical causes of anxiety. The thyroid gland, a butterfly-shaped organ in the front of the neck, produces hormones that regulate metabolism throughout the body, including the brain. Every cell in your body has thyroid hormone receptors, making thyroid function essential for normal physiology — and making thyroid dysfunction capable of affecting virtually every organ system.

Both overactive thyroid (hyperthyroidism) and underactive thyroid (hypothyroidism) can cause anxiety symptoms, though through different mechanisms. Thyroid disorders are common — affecting an estimated 10-12% of the population at some point — and are easily identified through blood testing. Yet thyroid function is often not checked in people presenting with anxiety.

Hyperthyroidism and anxiety:

Hyperthyroidism (overactive thyroid) is perhaps the classic medical mimic of anxiety — and one of the most important to identify because untreated hyperthyroidism has serious health consequences including heart problems (atrial fibrillation, heart failure), bone loss (osteoporosis), and thyroid storm (a life-threatening crisis).

Excess thyroid hormone puts the body into a state of metabolic overdrive that closely resembles — and actually is — the “fight or flight” stress response. The symptoms overlap so much with anxiety that misdiagnosis is common:

• Rapid heart rate and palpitations: Thyroid hormone directly affects the heart, increasing both rate and contractility. People feel their heart racing, pounding, or beating irregularly — symptoms identical to anxiety. Hyperthyroidism can actually cause atrial fibrillation (an irregular heart rhythm).
• Tremor: Fine trembling of the hands is characteristic of hyperthyroidism. It’s often most noticeable when hands are extended. This tremor is indistinguishable from anxiety-related tremor.
• Sweating and heat intolerance: Increased metabolism generates excess heat. People with hyperthyroidism sweat more, feel warm when others are comfortable, and may need to dress lighter or keep rooms cooler.
• Restlessness and irritability: The metabolic overdrive creates internal agitation. People feel unable to relax, easily annoyed, and may have difficulty sitting still.
• Difficulty sleeping: Despite exhaustion, sleep is often disrupted. The body’s accelerated state makes it difficult to wind down.
• Weight loss despite normal or increased appetite: The body burns calories faster than they can be consumed. This is often one clue that distinguishes hyperthyroidism from primary anxiety.
• Nervousness and feeling “wired”: Many people describe feeling like they’ve had too much caffeine — jittery, on edge, unable to calm down.
• Muscle weakness: Particularly in the upper arms and thighs, making it difficult to climb stairs or lift objects.
• Increased bowel movements or diarrhea: The GI tract speeds up along with everything else.
• Menstrual irregularities: Periods may become lighter, less frequent, or stop entirely.
• Fatigue: Despite the hypermetabolic state, people are often exhausted — the body is running on overdrive.

The overlap between hyperthyroidism and anxiety is so significant that some people are treated for anxiety disorders for months or years — taking anti-anxiety medications, undergoing therapy — before someone thinks to check thyroid function and discovers the true cause. This delay is unfortunate because hyperthyroidism is readily treatable, and anxiety symptoms typically resolve once thyroid levels normalize.

Graves’ disease, the most common cause of hyperthyroidism, is an autoimmune condition where antibodies stimulate the thyroid to overproduce hormone. Graves’ disease can also affect the eyes (causing bulging, redness, irritation, and double vision) and, rarely, the skin. Other causes of hyperthyroidism include toxic nodular goiter, thyroiditis (inflammation), and excessive thyroid medication.

Hypothyroidism and anxiety:

While hypothyroidism (underactive thyroid) is more commonly associated with depression, fatigue, and cognitive slowing, it can also cause or worsen anxiety — a fact that’s often surprising to both clinicians and those affected:

• Compensatory stress hormone release: When thyroid hormone is low, the body may increase production of adrenaline and noradrenaline to maintain essential functions. These are the same stress hormones released during anxiety, and they cause the same symptoms — racing heart, sweating, trembling, and nervousness.
• Brain effects: Thyroid hormone affects multiple neurotransmitter systems including serotonin (the “calm and happy” neurotransmitter), dopamine, and GABA (the brain’s primary calming neurotransmitter). Imbalances in these systems are implicated in anxiety.
• Cognitive symptoms creating anxiety: The difficulty concentrating, memory problems, and mental fog of hypothyroidism can themselves create anxiety — people worry about their declining cognitive function, wonder if something is seriously wrong, and feel anxious about their ability to perform at work or manage daily life.
• Fatigue leading to overwhelm: When everything feels harder due to profound fatigue, anxiety about coping with responsibilities often follows.
• Sleep disturbances: Hypothyroidism can cause sleep apnea and non-restorative sleep, and poor sleep significantly worsens anxiety.

Hashimoto’s thyroiditis, the autoimmune cause of most hypothyroidism, deserves special mention. In the early stages of Hashimoto’s, the inflamed thyroid can leak stored hormone into the bloodstream, causing temporary hyperthyroid symptoms (including significant anxiety) before the thyroid eventually burns out and becomes underactive. This “hashitoxicosis” phase can cause puzzling symptom patterns — anxiety that comes and goes, fluctuating between feeling wired and feeling exhausted. Some people cycle between hyper and hypo symptoms before settling into stable hypothyroidism.

Subclinical thyroid dysfunction:

Even mild thyroid abnormalities can affect anxiety. Subclinical hyperthyroidism (low TSH with normal T4/T3) and subclinical hypothyroidism (elevated TSH with normal T4/T3) are common and can cause symptoms including anxiety, even though hormone levels are technically “normal.” These borderline cases are sometimes overlooked but may benefit from treatment or monitoring.

What to test:

TSH (Thyroid Stimulating Hormone) is the primary screening test and should be checked in nearly everyone with unexplained anxiety. Low TSH suggests hyperthyroidism (the pituitary gland senses excess thyroid hormone and backs off its stimulation); high TSH suggests hypothyroidism (the pituitary is working harder to stimulate an underperforming thyroid).

Free T4 and Free T3 measure actual circulating thyroid hormone levels and help characterize the severity and type of dysfunction.

TPO antibodies and thyroglobulin antibodies identify autoimmune thyroid disease (Hashimoto’s or Graves’). Positive antibodies indicate the immune system is attacking the thyroid, even if TSH is still normal — this can explain symptoms and predict future thyroid problems.

Blood Sugar and Anxiety

Blood sugar problems — both low blood sugar (hypoglycemia) and the fluctuations associated with insulin resistance — are common but often unrecognized causes of anxiety symptoms. The brain is remarkably dependent on glucose for fuel — it uses about 20% of the body’s glucose despite being only 2% of body weight. Unlike muscles, which can switch to burning fat when glucose is limited, neurons rely almost exclusively on a steady glucose supply. This makes the brain exquisitely sensitive to blood sugar changes, and disruptions trigger alarm responses that feel identical to anxiety.

The blood sugar-anxiety connection is often overlooked because people don’t connect their symptoms to eating patterns. Understanding this connection can lead to simple, highly effective interventions.

Hypoglycemia and anxiety:

When blood sugar drops below normal levels, the body responds with a surge of counter-regulatory hormones — particularly adrenaline (epinephrine), cortisol, glucagon, and growth hormone — designed to raise glucose levels. This hormonal surge, especially the adrenaline component, produces symptoms that are virtually indistinguishable from a panic attack:

• Rapid heartbeat and palpitations — adrenaline directly increases heart rate
• Sweating — particularly cold, clammy sweating
• Trembling and shaking — the adrenaline effect on muscles
• Intense anxiety and sense of dread — the brain is perceiving danger (it needs glucose to survive)
• Irritability and mood changes — the brain isn’t functioning optimally
• Difficulty concentrating and confusion — neurons lacking fuel
• Dizziness and lightheadedness — inadequate glucose to the brain
• Weakness and fatigue
• Hunger — often intense, urgent hunger
• Pallor — blood shunted away from skin
• Tingling or numbness around the mouth or in the fingers

Many people experiencing these symptoms believe they’re having a panic attack when they’re actually hypoglycemic. The physiological experience is nearly identical — because the underlying mechanism (adrenaline surge) is the same. The key difference is the trigger and the timing.

Hypoglycemic symptoms typically occur in recognizable patterns:

• When meals are skipped or significantly delayed — the classic scenario is feeling terrible in late afternoon after skipping or having a very light lunch
• Several hours after eating, particularly after high-carbohydrate meals (reactive hypoglycemia)
• In the morning before breakfast, especially after a light or early dinner the night before
• During the night, sometimes waking the person with sweating, palpitations, and anxiety — some “nightmares” are actually hypoglycemic episodes
• After intense exercise, particularly if inadequate fuel was consumed
• After alcohol consumption, as alcohol impairs the liver’s ability to release glucose

If “anxiety attacks” consistently occur in relation to eating patterns and improve rapidly (within 10-15 minutes) with food, blood sugar involvement is highly likely. This rapid response to eating is a key diagnostic clue.

Reactive hypoglycemia and insulin resistance:

Reactive hypoglycemia presents a paradox that confuses many people: they experience anxiety symptoms 2-4 hours after eating rather than from skipping meals. How can eating cause low blood sugar?

The mechanism involves insulin overshoot:

1. You eat, particularly a high-carbohydrate meal (pasta, bread, sweets, sugary drinks)
2. Blood sugar rises rapidly
3. The pancreas releases insulin to bring blood sugar down
4. Insulin is released in excess — more than needed
5. Blood sugar crashes below normal (the “reactive” hypoglycemia)
6. The body releases adrenaline to raise blood sugar back up
7. You experience anxiety symptoms from the adrenaline surge

This pattern is particularly common in people with insulin resistance — a condition where cells don’t respond efficiently to insulin, prompting the pancreas to produce more. The blood sugar “rollercoaster” — spiking high after meals then crashing low — causes symptoms even when average glucose levels appear acceptable on standard testing.

Insulin resistance is extremely common, affecting an estimated 40% of young adults and even more in older populations. It’s a precursor to type 2 diabetes, often by years or decades. The metabolic instability of insulin resistance affects not just glucose but also inflammation, hormone balance, and neurotransmitter function — all of which can contribute to anxiety.

Studies consistently show that people with insulin resistance and metabolic syndrome have higher rates of anxiety disorders. The relationship appears bidirectional — anxiety can worsen metabolic dysfunction, and metabolic dysfunction can worsen anxiety — creating a vicious cycle.

Diabetes and anxiety:

Diabetes and anxiety frequently co-occur — people with diabetes have significantly higher rates of anxiety disorders than the general population. Several factors contribute:

• Blood sugar fluctuations: Even with treatment, diabetes involves more glucose variability than normal, which can trigger anxiety symptoms directly
• Hypoglycemia from medications: Insulin and certain diabetes medications (particularly sulfonylureas) can cause blood sugar to drop too low, triggering the adrenaline-mediated anxiety symptoms described above
• Fear of hypoglycemia: Many people with diabetes develop significant anxiety about low blood sugar episodes, particularly if they’ve had severe episodes
• The psychological burden: Managing a chronic condition with constant vigilance, dietary restrictions, medication schedules, and potential complications is inherently stressful
• Shared underlying mechanisms: Inflammation, stress hormone dysregulation, and autonomic nervous system dysfunction contribute to both diabetes and anxiety

What to test:

Fasting glucose measures blood sugar after an overnight fast and screens for diabetes and prediabetes.

HbA1c reflects average blood sugar over 2-3 months and can identify diabetes or prediabetes that might be missed by a single fasting glucose.

Fasting insulin identifies insulin resistance even when glucose appears normal. Elevated fasting insulin indicates the body is working hard to maintain glucose control — a state associated with metabolic instability, blood sugar swings, and increased anxiety risk. This test is often not done routinely but can be very informative for people with anxiety symptoms that seem related to eating patterns.

Nutritional Deficiencies

Several nutritional deficiencies can cause or worsen anxiety by affecting brain function, neurotransmitter production, and nervous system health. These deficiencies are common, often overlooked, and typically easy to correct — making them important to identify in anyone with anxiety symptoms.

Vitamin B12 deficiency:

B12 is essential for nervous system function, myelin formation (the insulating sheath around nerves), DNA synthesis, and neurotransmitter production. Deficiency can cause a broad range of neurological and psychiatric symptoms that are often not recognized as B12-related:

• Anxiety and nervousness
• Depression and mood changes
• Irritability
• Cognitive difficulties — memory problems, difficulty concentrating, mental fog
• Fatigue and weakness
• Numbness and tingling in hands and feet (peripheral neuropathy)
• Balance problems
• In severe cases, confusion, paranoia, or psychosis

What makes B12 deficiency particularly important is that neurological and psychiatric symptoms can appear before — sometimes long before — anemia develops. Many people with low B12 have normal blood counts, so the deficiency is missed if only a CBC is checked.

B12 deficiency is common in several groups:

• Vegetarians and vegans: B12 is found almost exclusively in animal products (meat, fish, eggs, dairy). Without supplementation, plant-based diets lead to deficiency over time.
• Older adults: Stomach acid production decreases with age, and acid is needed to release B12 from food. Up to 30% of older adults have reduced B12 absorption.
• People taking certain medications: Metformin (for diabetes), proton pump inhibitors (for acid reflux), and H2 blockers all reduce B12 absorption.
• Those with pernicious anemia: An autoimmune condition destroying cells that produce intrinsic factor, needed for B12 absorption.
• People with GI conditions: Celiac disease, Crohn’s disease, gastric bypass surgery, and other conditions affecting the stomach or small intestine can impair B12 absorption.

Anxiety from B12 deficiency may be accompanied by the neurological symptoms mentioned above. If you have anxiety plus tingling in your hands or feet, balance problems, or cognitive changes, B12 testing is particularly important.

Vitamin D deficiency:

Vitamin D receptors are present throughout the brain, including areas involved in mood regulation, fear response, and anxiety. Deficiency is extremely common — affecting an estimated 40-75% of adults depending on the population studied — and has been associated with increased anxiety and depression in numerous research studies.

The mechanisms linking vitamin D to anxiety may include:

• Neurotransmitter synthesis: Vitamin D influences the production of serotonin (the “feel good” neurotransmitter) and dopamine
• Brain inflammation: Vitamin D has anti-inflammatory effects; deficiency may allow increased brain inflammation
• HPA axis regulation: Vitamin D affects the hypothalamic-pituitary-adrenal axis, the body’s central stress response system
• Calcium regulation: Vitamin D is essential for calcium metabolism, and calcium affects nerve function

Vitamin D deficiency is more common in people who spend most time indoors, live in northern latitudes, have darker skin (melanin reduces vitamin D synthesis), are older, are overweight (vitamin D is sequestered in fat tissue), or consistently use sunscreen.

Magnesium deficiency:

Magnesium plays crucial roles in hundreds of enzymatic reactions, including many affecting nervous system function. Deficiency is strongly linked to anxiety, and supplementation has been shown to reduce anxiety symptoms in research studies:

• GABA regulation: Magnesium modulates GABA receptors — GABA is the brain’s primary calming, inhibitory neurotransmitter. Low magnesium means less GABA activity and more neural excitability.
• Glutamate control: Magnesium helps regulate glutamate, an excitatory neurotransmitter. Deficiency leads to excessive neural excitation — essentially, an overstimulated, anxious brain.
• HPA axis modulation: Magnesium regulates the stress response. Deficiency is associated with elevated cortisol and exaggerated stress reactions.
• Serotonin production: Magnesium is involved in serotonin synthesis.
• Muscle relaxation: Low magnesium causes muscle tension, which contributes to the physical component of anxiety.

Magnesium deficiency is common due to several factors: modern processed diets are low in magnesium; chronic stress depletes magnesium; certain medications (diuretics, proton pump inhibitors) reduce magnesium; and various conditions (diabetes, GI disorders) impair absorption. Symptoms of deficiency include anxiety, irritability, insomnia, muscle cramps and twitching, and heart palpitations — many of which overlap with anxiety disorders.

Note that blood magnesium levels don’t always reflect tissue stores — only about 1% of body magnesium is in the blood, with the rest in bones and cells. A normal blood level doesn’t completely rule out deficiency at the tissue level.

Iron deficiency:

Iron is necessary for neurotransmitter synthesis (including dopamine and serotonin), brain oxygenation, and myelin production. Even without anemia, low iron stores (low ferritin) have been associated with anxiety, particularly in women. Iron deficiency can contribute to anxiety through several mechanisms:

• Dopamine and serotonin effects: Iron is a cofactor in neurotransmitter synthesis
• Fatigue: The fatigue of iron deficiency can worsen anxiety about coping with responsibilities
• Restless legs syndrome: Low iron is associated with restless legs, which disrupts sleep and increases anxiety
• Palpitations and shortness of breath: These symptoms of iron deficiency can mimic or trigger anxiety
• Brain oxygenation: Iron carries oxygen; deficiency reduces oxygen delivery to the brain

What to test:

Vitamin B12 — essential, especially if neurological symptoms or risk factors are present

Vitamin D (25-OH) — given widespread deficiency, worth testing in most people with anxiety

Magnesium — though blood levels don’t always reflect tissue stores, low blood magnesium definitely indicates deficiency

Ferritin (iron stores) — more sensitive than hemoglobin for detecting early iron deficiency

CBC — screens for anemia, though deficiencies can cause symptoms before anemia develops

Folate — deficiency can affect mood and often co-occurs with B12 deficiency

Hormonal Causes of Anxiety

Hormonal fluctuations and imbalances beyond thyroid dysfunction can significantly impact anxiety levels.

Female hormone fluctuations:

Many women experience anxiety related to hormonal changes:

Premenstrual anxiety: The drop in estrogen and progesterone before menstruation can trigger anxiety in susceptible women. Premenstrual dysphoric disorder (PMDD) involves severe anxiety, irritability, or depression in the week before the period.

Perimenopause and menopause: The hormonal fluctuations of perimenopause often bring new or worsened anxiety. Estrogen affects serotonin and other neurotransmitter systems; as levels become erratic and then decline, anxiety commonly increases. Hot flashes and night sweats (which disrupt sleep) compound the problem. Women who never had anxiety may develop it during this transition.

Postpartum period: Dramatic hormonal shifts after delivery, combined with sleep deprivation and the stress of caring for a newborn, can trigger postpartum anxiety (which may be more common than postpartum depression).

Cortisol dysregulation:

Cortisol is the body’s primary stress hormone. Normally, cortisol follows a daily rhythm — highest in the morning, declining through the day. Chronic stress can dysregulate this pattern:

• Chronically elevated cortisol keeps the body in a state of hypervigilance
• Flattened cortisol rhythm (loss of normal variation) is associated with anxiety and fatigue
• Adrenal dysfunction — while controversial in some medical circles — may contribute to anxiety symptoms

Cortisol testing (ideally morning cortisol or a cortisol rhythm test) can be informative when adrenal dysfunction is suspected.

Testosterone:

Low testosterone in men has been associated with increased anxiety and depression. Testosterone has anxiolytic (anxiety-reducing) effects, and deficiency can contribute to mood symptoms alongside other low-T symptoms like fatigue, decreased libido, and reduced muscle mass.

What to test:

Estradiol, progesterone, FSH, and LH for women with symptoms suggesting hormonal involvement

Testosterone (total and free) for men with low-T symptoms

Cortisol when adrenal dysfunction is suspected

Other Medical Conditions Causing Anxiety

Anemia:

Anemia reduces oxygen delivery to the brain and triggers compensatory responses (increased heart rate, increased breathing) that mimic anxiety. The fatigue of anemia can also worsen anxiety about daily functioning. Iron deficiency anemia, B12 deficiency anemia, and other types can all contribute.

Heart conditions:

Arrhythmias (abnormal heart rhythms), mitral valve prolapse, and other cardiac conditions can cause palpitations, chest discomfort, and shortness of breath that feel like anxiety — or can trigger genuine anxiety about heart health. When anxiety symptoms include significant cardiac symptoms, cardiac evaluation may be warranted alongside other testing.

Respiratory conditions:

Asthma, COPD, and other breathing problems can cause shortness of breath and chest tightness that trigger or mimic anxiety. The sensation of not being able to breathe easily is inherently anxiety-provoking.

Caffeine and stimulants:

Excessive caffeine is a common and easily correctable cause of anxiety symptoms. Caffeine blocks adenosine receptors, increases adrenaline, and can cause rapid heartbeat, restlessness, tremor, and anxiety — especially in sensitive individuals or at high doses. Many people don’t realize how much caffeine they’re consuming from coffee, tea, energy drinks, and soda combined.

Medications and substances:

Many medications can cause anxiety as a side effect, including:

• Stimulant medications (ADHD medications, decongestants)
• Thyroid medication (if dose is too high)
• Corticosteroids
• Some asthma medications
• Withdrawal from alcohol, benzodiazepines, or other substances

Chronic inflammation:

Emerging research links systemic inflammation to anxiety and depression. Inflammatory cytokines can affect brain function and neurotransmitter systems. Conditions causing chronic inflammation — autoimmune diseases, chronic infections, metabolic syndrome, and others — may contribute to anxiety through this mechanism.

Testing CRP or hs-CRP can identify elevated inflammation.

The Testing Strategy for Anxiety

Not everyone with anxiety needs extensive blood testing. But when clinical features suggest a possible medical contribution, testing can identify treatable causes.

Core tests when medical causes are suspected:

Thyroid function:

• TSH — essential, should be checked in nearly everyone with unexplained anxiety
• Free T4 and Free T3 if TSH is abnormal
• TPO antibodies if thyroid dysfunction is found or suspected

Blood sugar:

• Fasting glucose
• HbA1c
• Fasting insulin if insulin resistance is suspected

Complete blood count:

• CBC — screens for anemia

Nutritional markers:

• Vitamin B12
• Vitamin D
• Ferritin (iron stores)
• Magnesium

Metabolic panel:

• Electrolytes, kidney function, liver function

Additional tests based on clinical picture:

• Hormone levels (estradiol, progesterone, testosterone) when hormonal factors suspected
• Cortisol when adrenal dysfunction suspected
• Inflammatory markers (CRP) when chronic inflammation possible
• Cardiac evaluation if significant cardiac symptoms

What to Do With the Results

If thyroid dysfunction is found:

Treatment of hyperthyroidism (with medication, radioactive iodine, or surgery) often dramatically reduces anxiety as thyroid levels normalize. Treatment of hypothyroidism with thyroid hormone replacement can also improve mood and anxiety. Anxiety improvement typically occurs over weeks to months as thyroid function stabilizes.

If blood sugar abnormalities are found:

Stabilizing blood sugar through dietary changes (regular meals with protein and complex carbohydrates, limiting refined sugars), exercise, and sometimes medication can significantly reduce anxiety symptoms related to glucose instability. The improvement can be noticed within days to weeks.

If nutritional deficiencies are found:

B12 supplementation (oral or injections depending on severity and cause), vitamin D supplementation, magnesium supplementation, or iron replacement can improve anxiety over weeks to months as levels normalize. The timeline varies by nutrient and severity of deficiency.

If hormonal imbalances are found:

Treatment depends on the specific imbalance — hormone replacement therapy for menopause, treatment of underlying conditions, or other approaches. Working with an endocrinologist or hormone specialist may be beneficial.

When Tests Are Normal

Normal blood tests rule out many medical causes of anxiety — and that’s valuable information. It means the focus can shift to other approaches:

• Primary anxiety disorders: Generalized anxiety disorder, panic disorder, social anxiety, and other conditions are real and treatable. Evidence-based treatments include cognitive behavioral therapy (CBT), exposure therapy, and medications when appropriate.
• Lifestyle factors: Caffeine reduction, regular exercise, adequate sleep, stress management techniques, and limiting alcohol can significantly impact anxiety.
• Other medical conditions: Some causes of anxiety (like heart arrhythmias) require different types of testing. If anxiety has prominent physical symptoms, further evaluation may be warranted.
• Gut-brain connection: Emerging research highlights the role of gut health in mental health. While blood tests don’t assess the microbiome, gut-focused interventions are an area of growing interest.

Lifestyle Approaches for Managing Anxiety

Whether or not a medical cause is found, these evidence-based strategies can help reduce anxiety. Many of these approaches work by addressing the same physiological systems that medical conditions affect — stabilizing blood sugar, supporting neurotransmitter function, regulating the stress response, and optimizing brain health.

• Regular exercise: One of the most effective anxiety treatments available, with benefits comparable to medication in some studies. Exercise reduces stress hormones (cortisol, adrenaline), increases endorphins and endocannabinoids (natural mood boosters), improves sleep quality, builds confidence and self-efficacy, and provides a healthy outlet for anxious energy. Both aerobic exercise (walking, running, swimming, cycling) and resistance training help. Aim for at least 30 minutes most days. Even a single session of exercise can reduce anxiety for several hours.
• Stable blood sugar: Eat regular meals with protein, healthy fats, and complex carbohydrates at each meal. Protein and fat slow glucose absorption, preventing the rapid spikes and crashes that trigger adrenaline release. Avoid skipping meals — going too long without eating is a common anxiety trigger. Limit sugar and refined carbohydrates (white bread, pastries, sugary drinks) that cause glucose spikes. If you notice anxiety symptoms 2-4 hours after eating, try having a protein-rich snack mid-morning and mid-afternoon.
• Limit caffeine: Reduce or eliminate caffeine if you’re sensitive — this is one of the simplest and most effective interventions for many people. Caffeine stays in the system for 5-6 hours (longer in some people) and can significantly worsen anxiety. Remember that caffeine is present in coffee, tea, energy drinks, soda, chocolate, and some medications. If you currently consume a lot of caffeine, taper gradually to avoid withdrawal symptoms.
• Prioritize sleep: Sleep deprivation dramatically increases anxiety — studies show that even partial sleep restriction increases anxiety and emotional reactivity. Aim for 7-9 hours per night. Maintain consistent sleep and wake times, even on weekends. Practice good sleep hygiene: keep the bedroom dark, cool, and quiet; avoid screens before bed; limit alcohol (it disrupts sleep quality); avoid caffeine after noon.
• Stress management practices: Practices like meditation, deep breathing, progressive muscle relaxation, and yoga have solid scientific evidence for reducing anxiety. These practices activate the parasympathetic nervous system (the “rest and digest” system that counteracts the stress response) and can reduce cortisol levels. Even a few minutes of daily practice can help. Apps like Headspace, Calm, or Insight Timer make it easy to start.
• Limit alcohol: While alcohol may temporarily reduce anxiety (it enhances GABA, the calming neurotransmitter), the net effect is negative. Alcohol disrupts sleep architecture, affects blood sugar, depletes B vitamins and magnesium, and increases anxiety during withdrawal — which occurs even after moderate drinking as blood alcohol levels fall. Many people find their anxiety significantly improves when they reduce or eliminate alcohol.
• Social connection: Isolation worsens anxiety; social support is protective. Maintaining relationships, talking to trusted friends or family, and seeking support are important. If anxiety is causing you to withdraw, recognize this as part of the condition and gently push against it.
• Reduce news and social media: Constant exposure to alarming information activates the stress response and perpetuates anxiety. Consider setting limits — checking news once or twice daily rather than constantly, taking breaks from social media, or curating your feeds to reduce anxiety-provoking content.
• Time in nature: Research consistently shows that time outdoors, particularly in green spaces, reduces anxiety and stress hormones. Even 20 minutes in a park can lower cortisol levels.

The Bottom Line

Anxiety is common, and its causes are diverse. While psychological factors play a major role for many people, medical conditions — particularly thyroid dysfunction, blood sugar abnormalities, and nutritional deficiencies — can cause or worsen anxiety symptoms in ways that are easily overlooked.

Blood testing can identify these treatable causes. When a medical condition is driving anxiety, treating it can provide dramatic relief — sometimes eliminating symptoms that have persisted for years. Even when tests are normal, the information helps direct treatment toward the most effective approaches.

If you’re struggling with anxiety, especially if it’s new, doesn’t respond to usual treatments, or is accompanied by physical symptoms, blood testing is a reasonable step. Understanding what’s happening in your body is the first step toward finding the right solution.

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Key Takeaways

• Anxiety symptoms can have medical causes — thyroid dysfunction, blood sugar problems, and nutritional deficiencies can all cause or worsen anxiety
• Hyperthyroidism closely mimics anxiety — rapid heartbeat, tremor, sweating, and nervousness are symptoms of both; a simple TSH test can distinguish them
• Blood sugar instability causes anxiety-like symptoms — hypoglycemia triggers adrenaline release that feels identical to panic attacks
• Nutritional deficiencies matter — B12, vitamin D, magnesium, and iron all affect brain function and anxiety levels
• Hormonal changes affect anxiety — perimenopause, menstrual cycles, and hormone imbalances can trigger or worsen anxiety
• Consider medical testing when — anxiety is new onset, doesn’t respond to treatment, has prominent physical symptoms, or is accompanied by other systemic symptoms
• Treatment of underlying conditions often resolves anxiety — thyroid treatment, blood sugar stabilization, or correcting deficiencies can be dramatically effective
• Normal tests are still valuable — they help direct treatment toward psychological approaches and lifestyle modifications
• Lifestyle factors significantly impact anxiety — exercise, stable blood sugar, adequate sleep, and stress management all help
• Caffeine is a common culprit — excessive caffeine causes anxiety symptoms in many people