Calcium, Urine

Urinary calcium levels reflects intake, rates of intestinal calcium absorption, bone resorption, and renal loss. Hypercalcemia of any cause raises urinary calcium excretion, and its measurement adds little to the differential diagnosis of hypercalcemia. Fasting calcium excretion is useful when assessing the contribution of abnormal renal tubular handling of calcium to disorders of calcium homeostasis.

Normal range:

Twenty-four " “hour urine: 100 " “300 mg/day

Random urine:

Males: 12 " “244 mg/g creatinine

Females: 9 " “328 mg/g creatinine

Use

Evaluation of patients with disorders of bone disease, calcium metabolism, and renal stones

Follow-up of patients on calcium therapy for osteopenia

Best test of calcium excretion in the investigation of possible familial benign hypocalciuric hypercalcemia

Interpretation

Increased In

Primary hyperparathyroidism

Humoral hypercalcemia of malignancy

Vitamin D excess

Sarcoidosis

Fanconi syndrome

Osteolytic bone metastases

Myeloma

Osteoporosis

Distal renal tubular acidosis

Idiopathic hypercalciuria

Thyrotoxicosis

Paget disease

Malignant neoplasm of breast or bladder

Decreased In

Familial hypocalciuric hypercalcemia

Hypoparathyroidism

Pseudohypoparathyroidism

Rickets and osteomalacia

Hypothyroidism

Celiac sprue

Steatorrhea

Limitations

Calcium and protein intake and phosphorus excretion alter urinary calcium excretion.

Decreases late in normal pregnancy.

About one third of hyperparathyroid patients have normal urine output.