Hypercalciuria in Patients with Normocalcemic Hyperparathyroidism and Stone Disease

Normocalcemic primary hyperparathyroidism (pHpth) may be associated with renal stone disease1−3. In pHpth the renal tubular reabsorption of calcium (Ca) is increased. Therefore, relative to the serum Ca concentration, the urinary Ca excretion is low in pHpth4. Theoretically normocalcemic hypercalciuric stone formers should not have pHpth. In contrast, we present a group of stone formers who probably have pHpth with hypercalciuria despite normocalcemia.