Endotoxin stimulated nitroblue-tetrazolium (NBT)-test in patients with hypoparathyroidism, pseudohypoparathyroidism and other forms of hypocalcemia.

Endotoxin-stimulated NBT-tests were carried out in 15 patients with hypocalcemia of varying etiology and in 14 normocalcemic children free of infection. In the control group the formazan cell percentage (FCP) was 73.8 +/- 1.6% (range 63% to 83%). In 5 patients with hypoparathyroidism or pseudohypoparathyroidism the FCP before treatment was lower than normal. Vitamin D3 therapy produced a rapid increase of serum calcium but normalisation of NBT-test was only achieved after a latent period of one or more months. Patients with hypocalcemic rickets and children with an acute relapse of the nephrotic syndrome also showed abnormal results. The clinical significance of the NBT-test in hypocalcemic conditions is discussed.