Rates and Calcium Concentrations of Sweat in Relation to Cystic Fibrosis

The authors of the recent article which failed to show a significant difference between sweat calcium concentrations of CF patients and control subjects, suggest that the findings refute our hyperpermeability hypothesis. They found sweat Ca of 0.32 to 1.67 mEq/liter in 26 control subjects and 0.42 to 2.03 mEq/liter in 16 CF patients. With these tremendous ranges many more subjects would be required to prove or disprove a difference. A difference undetectable in a moderate number of subjects is probably not of pathophysiologic significance if the Ca really varies unpredictably.