Evaluation of Excessive Sweating
The first priority is to systematically rule out secondary causes of hyperhidrosis through targeted laboratory testing, as treatable conditions like hyperthyroidism, diabetes, and pheochromocytoma are frequently missed when clinicians assume all excessive sweating is primary hyperhidrosis. 1, 2
Immediate Diagnostic Workup
Before considering any treatment, obtain the following laboratory tests to exclude secondary causes 1, 2:
- TSH and free T4 (hyperthyroidism is a major cause) 1, 2
- Hemoglobin A1c (diabetes mellitus affects thermoregulation) 2, 3
- Complete metabolic panel (to assess for kidney disease, electrolyte abnormalities) 1, 2
- Complete blood count (to evaluate for malignancies, infections) 1, 2
- Serum calcium (to screen for endocrine disorders) 2
Critical History Elements to Elicit
Pattern and Distribution
- Generalized vs. focal sweating: Generalized hyperhidrosis affecting the entire body suggests an underlying systemic condition (infection, endocrine disorder, malignancy), while focal hyperhidrosis limited to palms, soles, axillae, or face is more likely primary 4, 5, 6
- Bilateral symmetric involvement: Primary hyperhidrosis is characteristically bilateral and symmetric 6
Associated Symptoms That Point to Secondary Causes
- Heat intolerance, weight loss, palpitations: Suggests hyperthyroidism 2, 3
- Night sweats: Consider malignancies (lymphoma, leukemia, lung cancer) 2
- Episodic sweating with headaches, palpitations: Pheochromocytoma 1, 2
- Flushing, diarrhea: Carcinoid syndrome 2
- Tremor, rigidity: Parkinson's disease 2, 3
- Polyuria, polydipsia: Diabetes mellitus or diabetes insipidus 2
- Recent fever or gastrointestinal illness: Impairs thermoregulation even after apparent recovery 2
Medication Review
Systematically review for medications that cause hyperhidrosis 2, 3:
- Anticholinergic drugs (paradoxically affect thermoregulation) 2
- Dopamine-reuptake inhibitors (ADHD medications) 2
- Antipsychotics 2
- Diuretics 2
- Oral retinoids 2
Other Medical Conditions to Screen For
- Sleep apnea: Can trigger excessive sweating 2
- Heart failure: May present with diaphoresis 2
- Obesity: Increases sweating through mechanical friction and inflammatory mechanisms 2
- Menopause: Common cause in women 2
- Social anxiety disorder: Sweating triggered by anxiety-provoking situations 2
Common Diagnostic Pitfalls to Avoid
The most critical error is assuming all hyperhidrosis is primary without systematically excluding secondary causes, particularly thyroid dysfunction and diabetes, which are readily treatable. 1, 2 This represents a failure to prioritize patient morbidity and mortality.
Overlooking medication-induced hyperhidrosis is another frequent mistake—always review the complete medication list for agents affecting thermoregulation. 2
In patients with recent illness, recognize that fever or gastrointestinal symptoms significantly impair thermoregulation even weeks after apparent recovery. 2
Clinical Context Considerations
Exercise-Related Sweating
If sweating occurs primarily during exercise in hot weather, consider physiological causes first 7:
- Inadequate hydration: Fluid losses can exceed 2 L/hour during intense activity in heat 7
- Heat acclimatization status: Requires 12-14 days for moderate heat adaptation 7
- Environmental conditions: Air temperature >70°F requires pace adjustment and increased fluid intake 7
Specific Patient Populations
- Cystic fibrosis patients: Have impaired thermoregulation and may require sodium supplementation (1-4 mmol/kg/day for infants) 7
- Patients with osteogenesis imperfecta: May have elevated metabolic rate (46.0 ± 10.2 kcal/h) and excessive sweating as a metabolic feature 7
- Cardio-facio-cutaneous syndrome: Heat intolerance and excessive sweating are cardinal features 7