Clinical differentiation of primary from secondary hyperhidrosis.

BACKGROUND: Hyperhidrosis (HH) is excessive sweating that may be primary (idiopathic) or secondary to medication or disease. Clinical features supporting primary or secondary etiology have not been well documented.
OBJECTIVE: To identify clinical and demographic features predictive of a diagnosis of primary versus secondary HH.
METHODS: A retrospective chart review was conducted over a 13-year period (1993-2005) of all patients (children and adults) seen at a university-based outpatient dermatology department with an International Classification of Diseases, 9th revision diagnosis code for HH (N = 415).
RESULTS: Three hundred eighty-seven patients (93.3%) had primary HH (PHH); 28 patients (6.7%) had secondary HH (SHH). SHH patients were older (39.0 ± 18.6 years vs 27.3 ± 12.3 years) with more frequent onset at age older than 25 years (55% for SHH vs12.1% for PHH; odds ratio [OR] 8.7; 95% confidence interval [CI] 3.5-21.4; P < .00001 for each). SHH was more often unilateral/asymmetric (OR: 51; 95% CI: 12.6-208), generalized (vs focal; OR: 18; 95% CI: 7.3-47.6), and present nocturnally (OR: 23.2; 95% CI: 4.3-126; P < .00001 for each). Of SHH cases, endocrine disease accounted for 57% (including diabetes mellitus [11], hyperthyroidism [4], and hyperpituitarism [1]). Neurologic disease accounted for 32% (including peripheral nerve injury [3], Parkinson's disease [2], reflex sympathetic dystrophy [2], spinal injury [1] and Arnold-Chiari malformation [1]). Malignancy (pheochromocytoma), respiratory disease, and psychiatric disease were each represented once. Compared to other secondary causes, asymmetric HH favored neurologic disease (OR: 63; 95% CI: 4.9-810); P = .0002). LIMITATIONS: Results were obtained from a single, university-based population.
CONCLUSIONS: On the basis of these data, the diagnostic criteria for PHH were assessed statistically. Criteria include: excessive sweating of 6 months or more in duration, with 4 or more of the following: primarily involving eccrine-dense (axillae/palms/soles/craniofacial) sites; bilateral and symmetric; absent nocturnally; episodes at least weekly; onset at 25 years of age or younger; positive family history; and impairing daily activities. These criteria discriminate well between PHH and SHH (sensitivity: 0.99; specificity: 0.82; positive predictive value: 0.99; negative predictive value: 0.852) and may facilitate optimal clinical management.