Hypercalciuria

Hypercalciuria is the condition of elevated calcium in the urine. Chronic hypercalciuria may lead to impairment of renal function, nephrocalcinosis, and chronic kidney disease. Patients with hypercalciuria have kidneys that excrete higher levels of calcium than normal, for which there are many possible causes. Calcium may come from one of two paths: through the gut where higher than normal levels of calcium are absorbed by the body or mobilized from stores in the bones. After initial 24 hour urine calcium testing and additional lab testing, a bone density scan (DSX) may be performed to determine if the calcium is being obtained from the bones. Hypercalciuria in patients can be due to underlying genetic causes. Signs and Symptoms There are no clinical signs or symptoms of hypercalciuria itself but elevated calcium in the urine can contribute to accelerated loss of calcium from bone leading to osteoporosis. Additionally, hypercalciuria can contribute to kidney stone formation which may present with flank or back pain that comes and goes. It can be painful to pass kidney stones and in extreme cases cause kidney damage. Patients that both form kidney stones and have hypercalciuria are at increased risk for bone loss leading to osteoporosis. There are a number of causes of hypercalciuria including genetic (idiopathic), primary hyperparathyroidism, immobilization, pagets disease, Multiple Myeloma, Calcium excess, Vitamin D excess/increased sensitivity, drug-induced hypercalciuria, sarcoidosis, hyperthyroidism, Cushing's disease, and renal tubular acidosis. Idiopathic hypercalciuria is defined as elevated calcium in the urine without an identifiable cause despite low to normal calcium intake and otherwise normal lab values. In addition to hypercalciuria, these individuals often have associated low bone density. There can be an underlying genetic component that is beyond current genetic testing available. In familial cases it is common that 50% of first degree relatives are affected.