Normal sweat secretion rate in patients with alopecia areata.

We have examined sweat secretion rates in 22 patients with alopecia areata, and 22 age- and sex-matched controls. Mean sweat rate on the forearm in patients with alopecia areata was 20 mg/cm2 per h (95% confidence limits 15-25 mg/cm2 per h), and in controls was 24.1 mg/cm2 per h (95% confidence limits 19.1-29.1 mg/cm2 per h). Sweat secretion was higher in males than females in both the disease and control groups (27.8 mg/cm2 per h [95% confidence limits 21.3-34.3 mg/cm2 per h], compared with 18.08 mg/cm2 per h [95% confidence limits 14.63-21.6 mg/cm2]; P > 0.01). Our results confirm the previously reported sex difference in sweat secretion rate, and demonstrate that there is no statistically significant difference between patients with alopecia areata and controls. We discuss our results in the light of a previous report claiming that patients with alopecia areata have reduced rates of cholinergic-induced sweating.