24-hour urine calcium test explained

Clinicians interpret it alongside your symptoms, blood tests, medicines, diet and kidney function. A result outside the laboratory range does not identify a cause by itself.

Calcium circulates in blood, supports bones and muscles, and is filtered by the kidneys. Measuring a whole day of urine gives a broader picture than a single sample because excretion changes with meals, fluids and time of day.

The test may help investigate kidney stones, altered blood calcium or concerns about calcium regulation. Higher or lower excretion can have several explanations, so the number must be considered with other findings.

Follow the laboratory’s start-time instructions. You will generally empty your bladder at the start without saving that urine, then collect every urination for the next 24 hours, including the final sample at the stated finish time.

Keep the container as instructed, often cool, and avoid contamination with stool, toilet paper or menstrual blood. If you miss a sample, spill urine or collect beyond the finish time, tell the laboratory because collection may need to restart.

Do not change calcium intake, supplements or prescribed medicines unless your clinician directs you. Record anything the laboratory asks about and return the container promptly.

The collection itself should not make you ill. Seek urgent care for severe pain in the side or back with vomiting, inability to pass urine, fainting, confusion, or visible blood in urine accompanied by severe symptoms.

Contact your clinician if you develop burning urination, fever, chills or worsening urinary discomfort. These symptoms require assessment based on their severity and are not explained by the calcium result alone.

Confirm the exact start and finish method, storage requirements, and whether your usual diet and medicines should continue. Afterward, ask how the urine calcium compares with blood calcium and kidney tests, and whether follow-up testing is planned.