Workup for Excessive Sweating (Hyperhidrosis)
The American Academy of Dermatology recommends obtaining TSH, free T4, hemoglobin A1c, complete metabolic panel, and complete blood count to systematically exclude secondary causes of hyperhidrosis before assuming primary disease. 1, 2
Initial Laboratory Evaluation
The cornerstone of hyperhidrosis workup is ruling out treatable secondary causes through targeted laboratory testing:
- TSH and free T4 to screen for hyperthyroidism (Graves disease), which increases metabolic rate and compensatory sweating 1, 3, 2
- Hemoglobin A1c to assess for diabetes mellitus, which affects thermoregulation 1, 3, 2
- Complete blood count to evaluate for malignancies (lymphoma, leukemia) and anemia 1, 2
- Complete metabolic panel to screen for kidney disease (uremic sweating), electrolyte abnormalities, and pheochromocytoma 1, 3, 2
- Serum calcium levels to evaluate for hypercalcemia-related conditions 1, 2
- Vitamin D level and iron studies as part of comprehensive metabolic assessment 1, 2
Focused History Components
Your history must specifically address these high-yield elements:
- Medication review: anticholinergics, dopamine-reuptake inhibitors (ADHD medications), diuretics, oral retinoids, and antipsychotics all affect thermoregulation 3, 2
- Timing and distribution: focal versus generalized sweating patterns help distinguish primary from secondary causes 2, 4
- Associated symptoms: palpitations, headaches, anxiety attacks (suggesting pheochromocytoma or anxiety disorder), weight changes, heat intolerance (hyperthyroidism), recent fever or gastrointestinal illness 3, 2
- Sleep disturbances: screen for sleep apnea, which triggers excessive sweating 3, 2
Physical Examination Priorities
Target your examination to identify secondary causes:
- Vital signs: hypertension and tachycardia (pheochromocytoma, hyperthyroidism, heart failure) 2
- Thyroid examination: enlargement or nodules suggesting thyroid disease 2
- Cardiovascular assessment: signs of heart failure (diaphoresis is a common manifestation) 3, 2
- Body habitus: obesity increases sweating through mechanical friction and sweat retention 3
- Neurological examination: findings suggesting Parkinson's disease, stroke, multiple sclerosis, or other autonomic dysfunction 3, 2
Additional Screening
Beyond initial laboratory work, consider:
- Sleep study referral if sleep apnea is suspected based on history 3, 2
- Psychiatric assessment for social anxiety disorder, which can manifest as hyperhidrosis in anxiety-provoking situations 3
Specialist Referral Indications
Refer when you identify:
- Abnormal thyroid function or suspected thyroid malignancy 2
- Diabetes or hypoglycemia 2
- Suspected pheochromocytoma (episodic sweating with headaches, palpitations, hypertension) 3, 2
- Signs of Parkinson's disease, stroke, multiple sclerosis, or autonomic dysfunction 3, 2
- Evidence of heart failure or significant cardiovascular disease 3, 2
- Suspected carcinoid syndrome or other malignancies 3
Supplementary Diagnostic Tests for Primary Hyperhidrosis
If secondary causes are excluded, these tests quantify primary disease:
- Gravimetry: measures the amount of sweat produced 4, 5
- Iodine starch test: visualizes the area of sweating 4, 5
These are primarily useful for documenting severity and monitoring treatment response rather than diagnosis 5.
Critical Pitfalls to Avoid
Do not assume primary hyperhidrosis without completing the full laboratory workup—treatable conditions like thyroid dysfunction and diabetes are frequently missed when clinicians skip this step 1, 2. The American Academy of Dermatology emphasizes this is the most common diagnostic error 1.
Do not overlook medication-induced hyperhidrosis—reviewing the patient's medication list for anticholinergics, stimulants, and other thermoregulation-affecting agents is essential 3, 2.
In young patients with exercise-related sweating concerns, remember that recent illness with fever or gastrointestinal symptoms significantly impairs thermoregulation even after apparent recovery 3.