Calcium is an essential mineral involved in bone health, muscle contraction, and nerve function.

The 24-hour urinary calcium test provides a quantitative measure of calcium excretion.

Clinical uses include:

Diagnosing hypercalciuria (excess calcium in urine).

Evaluating risk of kidney stones.

Assessing parathyroid gland function (hyperparathyroidism, hypoparathyroidism).

Monitoring patients with metabolic bone diseases (osteoporosis, rickets).

The test requires collection of all urine passed in a 24-hour period.

Analyte: Calcium excreted in urine over 24 hours.

Normal Range: ~100 – 300 mg/24 hr (varies by lab, diet, and age).

Abnormal Findings:

High urinary calcium (hypercalciuria): Suggests hyperparathyroidism, excessive dietary calcium, vitamin D excess, or kidney stone risk.

Low urinary calcium (hypocalciuria): Suggests hypoparathyroidism, vitamin D deficiency, or malabsorption.

Clinical Use:

Helps identify causes of abnormal calcium metabolism.

Guides treatment for kidney stones and bone disorders.

Supports endocrine evaluation of parathyroid and vitamin D-related conditions.