What are the secondary causes of hyperhidrosis?

Secondary Causes of Hyperhidrosis

The main secondary causes of hyperhidrosis include endocrine disorders, neurological conditions, infections, medications, malignancies, and cardiovascular disorders.

Endocrine Causes

Endocrine disorders represent the most common secondary causes of hyperhidrosis (57% of secondary cases) 1:

• Thyroid disorders:

  • Hyperthyroidism - characterized by warm, moist skin; heat intolerance; nervousness; tremulousness; weight loss 2
  • Hypothyroidism (less commonly) - may present with cold intolerance and dry skin but can paradoxically cause hyperhidrosis in some cases 2

• Other endocrine disorders:

  • Diabetes mellitus (most common endocrine cause of secondary hyperhidrosis) 1
  • Hyperpituitarism 1
  • Pheochromocytoma - characterized by episodic hypertension and tachycardia 2, 1
  • Acromegaly - presents with acral enlargement, frontal bossing, headache 2
  • Hypercalcemia and primary hyperparathyroidism 2
  • Carcinoid syndrome 3

Neurological Causes

Neurological disorders account for approximately 32% of secondary hyperhidrosis cases 1:

• Peripheral nerve injury 1
• Parkinson's disease 1
• Reflex sympathetic dystrophy 1
• Spinal cord injury 1
• Arnold-Chiari malformation 1
• Autonomic neuropathy 4
• Stroke (particularly with asymmetric presentation) 3

Infections

• Tuberculosis 5
• Malaria 3
• HIV/AIDS 3
• Brucellosis 3
• Endocarditis 3

Medication-Induced Hyperhidrosis

• Antidepressants (particularly SSRIs and SNRIs) 3
• Antipyretics 3
• Insulin 3
• Opioids and opioid withdrawal 3
• Cholinergic agents 4
• Anticholinesterase inhibitors 3

Cardiovascular Causes

• Congestive heart failure 4
• Coronary heart disease 4
• Cardiac tachyarrhythmias 4
• Hypertension 4

Other Causes

• Malignancies (e.g., lymphoma, pheochromocytoma) 1, 6
• Respiratory diseases 1
• Psychiatric disorders 1
• Alcohol consumption and withdrawal 3
• Menopause 3
• Obesity 3

Clinical Features Distinguishing Secondary from Primary Hyperhidrosis

Secondary hyperhidrosis typically differs from primary hyperhidrosis in several key ways:

1. Age of onset: Secondary hyperhidrosis typically begins in the fourth decade of life or later, whereas primary hyperhidrosis usually begins in childhood or adolescence 3, 1

2. Distribution pattern:

   • Secondary hyperhidrosis is more often generalized (affecting the entire body) 5, 1
   • When focal, secondary hyperhidrosis is more likely to be unilateral or asymmetric (OR: 51; 95% CI: 12.6-208) 1
   • Primary hyperhidrosis typically affects eccrine-dense areas (axillae, palms, soles, face) symmetrically 1

3. Timing: Secondary hyperhidrosis is more likely to occur during sleep (nocturnal hyperhidrosis) (OR: 23.2; 95% CI: 4.3-126) 1

4. Associated symptoms: Secondary hyperhidrosis is often accompanied by symptoms of the underlying condition 3

5. Family history: Secondary hyperhidrosis typically lacks a family history, while primary hyperhidrosis often has a positive family history 1

Diagnostic Approach

When evaluating a patient with hyperhidrosis, the following features strongly suggest a secondary cause:

• Onset after age 25 (OR 8.7) 1
• Generalized distribution (OR 18) 1
• Unilateral/asymmetric presentation (OR 51) 1
• Nocturnal sweating (OR 23.2) 1
• Asymmetric hyperhidrosis strongly favors neurologic disease (OR 63) 1

Appropriate diagnostic workup should be guided by clinical suspicion of specific underlying causes, with particular attention to endocrine and neurological disorders as the most common etiologies.