Calcium, Urine

Reflects intake, rates of intestinal calcium absorption, bone resorption and renal loss. Those processes relate to parathyroid hormone and vitamin D levels. Evaluation of bone disease, calcium metabolism, renal stones (nephrolithiasis); idiopathic hypercalciuria, and especially, parathyroid disorders. Follow-up of patients on calcium therapy for osteopenia.

High in 30% to 80% of instances of primary hyperparathyroidism, but urinary calcium excretion does not consistently, reliably distinguish hyperparathyroidism from other entities. High in sarcoidosis. Increased with immobilization, with steroid therapy, with Paget disease, and in primary (idiopathic) hypercalciuria. Increased with entities causing high ultrafiltrable calcium: ectopic hyperparathyroidism, some cases of renal tubular acidosis, Fanconi syndrome, increased calcium intake, vitamin D intoxication, hyperthyroidism, diabetes mellitus, acromegaly, glucocorticoid excess, some cases of Crohn's disease and ulcerative colitis, myeloma, some instances of leukemia and lymphoma, and carcinoma metastatic to bone. Reported relationship to hematuria in children.

Low in familial hypocalciuric hypercalcemia, for which urine calcium measurements are mandatory; low with thiazide diuretics, vitamin D deficiency, renal osteodystrophy, vitamin D resistant rickets, hypoparathyroidism, pseudohypoparathyroidism and preëclampsia.