Evaluation of sweat production by pilocarpine iontophoresis: a noninvasive screening tool for hypohidrosis in ectodermal dysplasia

Ectodermal dysplasia (ED) is a genetic disorder affecting the skin, hair, nails, teeth and sweat glands. The clinical presentation is heterogenous; however, hypohidrotic (reduced sweat) ectodermal dysplasia (HED) being the commonest. Also known as anhidrotic ED, sweat glands are sparse or rudimentary, leading to dysregulation of body temperature and episodes of uncontrolled hyperthermia due to reduced sweating. Of the many aids to document hypohidrosis in HED, we present here the technique of pilocarpine iontophoresis to induce, collect and measure sweat. Evaluation of sweat generated (against normally obtained values) is a non-invasive alternative to establish hypohidrosis in disorders such as HED. This augments clinical decision levels to plan skin biopsy for confirmation of diagnosis and facilitates patient management and early discharge. We present two cases of HED that were primarily diagnosed with sweat gland dysplasia using pilocarpine iontophoresis, and later confirmed with skin biopsy findings.