A 24-hour urine calcium-to-creatinine ratio test measures the amount of calcium released in your urine over a full day, compared against creatinine, a steady muscle waste product. Collecting urine for 24 hours helps doctors account for daily fluctuations in your body's chemistry. This diagnostic tool is commonly used to evaluate mineral balance, assess the underlying causes of recurrent kidney stones, monitor metabolic bone diseases like osteoporosis, and check parathyroid gland function. Abnormal calcium excretion levels can highlight how well your kidneys process minerals, guiding targeted medical treatments and dietary management plans.