Sweat Composition in Relation to Rate of Sweating in Patients with Cystic Fibrosis of the Pancreas

Abstract

ExtractSingle sweat droplets were collected from a mineral oil-covered finger surface ( fig. 1). Rate of sweat production (sweat rate) per gland per hour was calculated. Using microtechniques, the concentrations of electrolytes and metabolites, osmolarity, pH, and viscosity were determined in undiluted pooled sweat. The following results were obtained:No significant difference was observed in sweat rate per gland between control subjects and patients with cystic fibrosis of the pancreas (CFP).Concentrations of sodium and chloride in sweat rose with increasing sweat rates in both control subjects and patients with CFP. In the patients with CFP, the lowest values were between 70 and 90 mEq/1 and the curve approached isotonicity. Chloride values were consistently lower than those of sodium. Concentrations of potassium decreased with increasing sweat rate in control subjects approaching a value of about 10 mEq/1. In patients with CFP, the values for potassium were frequently twice as high as those in the control subjects. Concentration of calcium dropped rapidly with an increasing sweat rate from 10 to 1-2 mEq/1.Concentrations of lactic acid and urea were high at low sweat rates and decreased hyperbolically with increasing rates. In patients with CFP, the values of both components were lower than those in control subjects. Urea was uniformly more concentrated in sweat than in plasma; the sweat:plasma ratio approached 1.0 with increasing sweat rates.Creatinine concentrations decreased with increasing sweat rate. No difference was observed between values in two patients and two control subjects. Glucose concentration was low (0.2-6 mg/100 ml) and was independent of the sweat rate. No significant difference was observed in comparing five patients with CFP and six control subjects.In control subjects, osmolarity decreased, with increasing sweat rate, from 240 to approximately 120 mOsmol/1 and then increased (mean 163 mOsmol/1). In patients with CFP, the curve was similar in shape but began and ended in a range of approximately 320 m/Osmol/1 (mean 299 mOsmol/1).The pH of sweat was acid at low sweat rates (pH 3.5-6.0) and was slightly alkaline (pH 7.0-8.5) at high rates. No differences were observed when comparing five patients and five control subjects.Viscosity of sweat was significantly elevated in five patients with CFP in relation to that observed in eight control subjects. This may be explained by the elevated concentration of salt in sweat of patients with CFP.The excretory pattern of urea, lactic acid, and creatinine in sweat of patients with CFP, compared with that of control subjects, argues against an increased rate of water reabsorption in the excretory ducts of the sweat gland. The course of the sodium and the chloride curve and the values of osmolarity EMRICH, STOLL, FRIOLET, COLOMBO, RIGHTERIGH, ROSSI 465 in sweat favor the assumption that in cystic fibrosis of the pancreas, the precursor fluid is in the isotonic range; net sodium reabsorption can then be calculated and appears to be defective in patients w...

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Micro-flowcell conductometric sweat analysis for cystic fibrosis diagnosis

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