Composition of palmar and forearm sweat

¹ Medical Research Council Unit for Research on Climate and Working Efficiency, Department of Human Anatomy, University of Oxford, Oxford, England

Sodium, chloride, lactate, and potassium concentrations were determined in capsule samples of sweat collected simultaneously on the palm and forearm from six normal and three hyperhidrotic subjects. The rate of sweat output on the forearm induced in the normal subjects by indirect heating or by intradermal injection of acetyl-ß-methylcholine always exceeded that on the palm. Similar sweat rates in the two regions were produced by exposing subjects with palmar hyperhidrosis to hot environments. The sodium and chloride concentrations in sweat from the two regions did not differ significantly. As with forearm sweat, palmar sweat sodium and chloride concentrations varied directly with the rate of secretion. Lactate and potassium concentrations were consistently higher in palmar samples. It is concluded that palmar sweat sodium chloride is well within the normal range of hypotonicity and that palmar sweat contains a slightly higher proportion of lactate and potassium than forearm sweat.