The cutaneous loss of nitrogen compounds in African adults

Loss of nitrogen compounds from the skin results from the activity of the sweat and other cutaneous glands, and from the shedding of epithelial structures.This loss may introduce significant errors into N-balance studies.Concentrations of 23-141 mg N/Ioo ml sweat have been quoted in the literature.The sweat used in the analyses was collected directly from the skin, often in hot, humid conditions.The daily excretion of N in sweat from the whole body has been determined by washing the whole body and any clothes with large volumes of distilled water and analysing the washings.Values of 0.071-5.28g N / q h have been given (see reviews by Robinson & Robinson (1954), and by Cuthbertson & Guthrie (1934)).Mitchell (1949) carried out N-balance studies on twenty-four healthy American students for periods of from 156 to 212 days, and found an 'apparent nitrogen retention' of 1-379 8/24 h which was attributed partly to unmeasured cutaneous loss.The work described here was undertaken primarily to ensure that N balances carried out under local tropical conditions were not invalidated by an underestimate of cutaneous N loss.An attempt has been made to measure the total N loss occurring in 24 h from all cutaneous structures, i.e. that in epithelial dCbris as well as in cutaneous secretions.School.