The tubular maximum for calcium reabsorption in patients with chronic active thoracic sarcoidosis

The tubular maximum for calcium reabsorption (TmCa) was evaluated in 52 patients with chronic active thoracic sarcoidosis. Hypercalcaemia was found in five patients (9.6%). The mean serum calcium value of 2.54 +/- 0.18 mmol.l-1 in patients with sarcoidosis was significantly higher than that obtained in the control group (2.42 +/- 0.11 mmol.l-1). The mean TmCa in patients with sarcoidosis (2.11 +/- 0.26 mmol.l-1 glomerular filtrate (GF] was not statistically different from the mean TmCa for the group of healthy subjects (2.18 +/- 0.23 mmol.l-1 GF). Urinary sodium corrected TmCa in both groups of patients was affected in a similar way. Our study demonstrates for the first time that there is no increase in TmCa in patients with chronic active thoracic sarcoidosis. Hypercalcaemia is not a result of an increased TmCa.