What medical conditions can cause excessive sweating (hyperhidrosis)?

Medical Conditions Causing Excessive Sweating (Hyperhidrosis)

Excessive sweating can be caused by numerous secondary medical conditions that must be systematically excluded before diagnosing primary hyperhidrosis, with endocrine disorders (particularly hyperthyroidism and diabetes), malignancies, neurological diseases, infections, and medications being the most common culprits. 1, 2

Endocrine and Metabolic Causes

• Hyperthyroidism (Graves disease) is a major cause, increasing metabolic rate and heat production with compensatory sweating 1, 2
• Diabetes mellitus (particularly type 2) impairs thermoregulation and can cause hyperhidrosis 1, 2
• Hypoglycemia triggers excessive sweating as an autonomic response 1
• Pheochromocytoma causes episodic sweating accompanied by headache, palpitations, and pallor 1, 2
• Carcinoid syndrome can manifest with hyperhidrosis 1
• Diabetes insipidus disrupts fluid balance and thermoregulation 1
• Hypothyroidism and other endocrinopathies may present with altered sweating patterns 3

Malignancies

• Lymphoma and leukemia are important causes of secondary hyperhidrosis 1
• Lung cancer (or metastasis to the lung) can present with night sweats 3
• Thyroid cancer may cause sweating disturbances 3

Neurological Disorders

• Parkinson's disease causes autonomic dysfunction leading to hyperhidrosis 1, 4
• Stroke can result in altered sweating patterns 1
• Autonomic dysfunction of various etiologies causes hyperhidrosis 1
• Spinal cord injury above T6 level can cause autonomic dysreflexia with blood pressure elevations and sweating 2
• Multiple sclerosis affects autonomic regulation 3
• Myasthenia gravis and amyotrophic lateral sclerosis may present with sweating abnormalities 3

Cardiovascular Causes

• Heart failure and other cardiovascular diseases may present with diaphoresis 1
• Hypertension itself or medications used to treat it can cause sweating 3

Renal Disease

• Chronic kidney disease causes uremic sweating 1

Infectious Causes

• Tuberculosis is a classic cause of night sweats 5
• Fever from any cause increases sweating 1
• Recent illness with gastrointestinal symptoms (vomiting, diarrhea) affects hydration and thermoregulation even after apparent recovery 1

Medication-Induced Hyperhidrosis

• Anticholinergic drugs paradoxically affect thermoregulation 1
• Dopamine-reuptake inhibitors (used for ADHD) impair sweating regulation 1
• Sympathomimetics including decongestants, cocaine, amphetamines, and ephedra cause fine tremor, tachycardia, and sweating 2
• Oral retinoids used in dermatological conditions can cause hyperhidrosis 1
• Diuretics affect hydration status 1
• Antipsychotics used for schizophrenia may cause sweating 3

Other Medical Conditions

• Menopause causes vasomotor symptoms including hyperhidrosis 1
• Obesity increases sweating through mechanical friction at flexural sites, sweat retention, and increased pro-inflammatory cytokines 1
• Cystic fibrosis impairs thermoregulation 1
• Sleep apnea and other sleep disorders trigger excessive sweating 1
• Social anxiety disorder manifests as hyperhidrosis where excessive sweating occurs in response to anxiety-provoking social situations 1
• Sjögren's syndrome affects sweat gland function 3

Essential Diagnostic Workup

The American Academy of Dermatology recommends a comprehensive laboratory evaluation including complete blood count, comprehensive metabolic panel, thyroid function tests (TSH, free T4), hemoglobin A1c, serum calcium levels, vitamin D level, and iron studies to identify secondary causes. 1, 2, 6

Critical Clinical Pitfalls

• Assuming all hyperhidrosis is primary without systematically excluding secondary causes is the most critical error, particularly missing thyroid dysfunction and diabetes which are readily treatable 1, 2, 6
• Overlooking medication-induced hyperhidrosis by failing to review the patient's medication list for anticholinergics, stimulants, and other agents affecting thermoregulation 1
• In young patients with exercise-related sweating concerns, failing to consider that recent illness with fever or gastrointestinal symptoms significantly impairs thermoregulation even after apparent recovery 1