In-vitro calcium uptake by jejunal biopsy specimens from patients with idiopathic hypercalciuria.

In-vitro calcium influx was measured in jejunal biopsy specimens from 10 men with idiopathic hypercalciuria. Calcium uptake in these adults was a passive process which was not sensitive to inhibition by 2,4 dinitrophenol and sodium fluoride, and showed no evidence of carrier saturation. In 7 of 10 patients with idiopathic hypercalciuria calcium uptake was above the normal range, and the mean uptake for all patients was significantly higher than in 10 control subjects (p < 0.01). The kinetic features suggest that this increased influx was the result of increased brush border permeability to calcium ions.