What is Hyperhidrosis?
Hyperhidrosis is a disorder of excessive sweating beyond what is physiologically necessary for thermoregulation, affecting approximately 3% of the population and causing significant medical and psychosocial impairment. 1, 2
Definition and Classification
Hyperhidrosis manifests as pathologically excessive focal or generalized sweating that substantially impacts quality of life, resulting in social and work impairment and emotional distress. 2, 3 The condition is mediated by eccrine sweat glands innervated by cholinergic fibers from the sympathetic nervous system. 4
Primary Hyperhidrosis
- Primary hyperhidrosis is bilaterally symmetric, focal, excessive sweating not caused by underlying medical conditions. 2
- The most commonly affected areas include axillae, palms, soles, and craniofacial regions where eccrine gland density is highest. 1, 2
- A critical distinguishing feature is that primary hyperhidrosis does not occur during sleep. 5
- The average age of onset is 14-25 years, though it can affect children and adults. 6
- Approximately half of all hyperhidrosis cases (1.4% of the U.S. population) involve the axillary form. 6
Secondary Hyperhidrosis
- Secondary hyperhidrosis may be focal or generalized and results from an underlying medical condition or medication use. 2
- The "SCREeN" approach should be used to evaluate underlying causes: Sleep disorders, Cardiovascular conditions, Renal disease, Endocrine disorders, and Neurological conditions. 5
- Hyperthyroidism is a major cause, directly affecting thermoregulation and sweating patterns. 5
- Heart failure can present with sweating as part of sympathetic activation. 5
- Unexplained night sweats should raise suspicion for underlying malignancy. 5
- Sleep apnea and other sleep disturbances can cause nocturnal hyperhidrosis. 5
Clinical Impact
- The stigmatizing nature causes patients to experience embarrassment, apprehension, and significant decrease in well-being. 3
- Severe cases increase the risk of developing psychiatric and somatic comorbidities. 3
- The disorder can be detrimental to social, professional, psychological, and physical well-being. 6
- Hyperhidrosis remains widely underdiagnosed and undertreated, particularly among pediatric patients. 6
Diagnostic Evaluation
When secondary hyperhidrosis is suspected, specific laboratory testing is required:
- Complete blood count and comprehensive metabolic panel should be obtained. 5
- Thyroid function tests to evaluate for hyperthyroidism. 5
- Hemoglobin A1c to evaluate for diabetes mellitus. 5
- Serum calcium levels to assess for hyperparathyroidism. 5
- A comprehensive medication review is mandatory, as numerous drugs can cause secondary hyperhidrosis, including certain antihypertensives, psychiatric medications, and hormonal therapies. 5
- Additional testing based on clinical suspicion may include morning urine osmolality, PTH, and overnight oximetry or polysomnography when sleep disorders are suspected. 5
Pathophysiology
- Sweat is secreted by eccrine glands innervated by cholinergic fibers from the sympathetic nervous system. 4
- In conditions like congenital ichthyosis, hypohidrosis (reduced sweating) results from plugging of sweat ducts by hyperkeratosis, though functional defects also exist. 7
- The condition represents excessive sweating beyond environmental conditions and thermoregulatory needs. 1