Platform
Company
Electrolytes
Review status
Currently under review
Pending specialist review and validation.
Urine 24 Hour Calcium measures the total amount of calcium you pass in your urine over a full day. Calcium supports bones, muscles, nerves, and blood clotting. Your kidneys filter calcium and excrete some into urine; this test captures your daily urinary calcium output.
You collect all urine for 24 hours in a provided container. The first void at the start time is discarded, then every void is saved, including the final one at the end time. The container may contain a preservative and is often kept cool. The laboratory analyzes the entire collection to report your total urinary calcium for that day.
The amount of calcium in your urine helps your clinician assess your risk for kidney stones and how your body handles calcium. High excretion can be related to diet, supplements, or medicines, and may point to conditions such as an overactive parathyroid gland. Low excretion can reflect low intake, vitamin D problems, or reduced kidney function.
This test is commonly ordered if you form kidney stones, have abnormal blood calcium, or there are concerns about bone loss or endocrine disorders. Results can guide treatment, including diet and fluid advice and medicines that change kidney handling of calcium, and can be used to monitor how well treatment is working.
Your result is interpreted with your age, diet, supplements, and medicines, plus blood tests such as calcium, creatinine, vitamin D, and parathyroid hormone. A result above the laboratory interval suggests increased urinary calcium, which can occur with high salt or calcium intake, high vitamin D intake, use of loop diuretics, inherited kidney calcium leak, or primary hyperparathyroidism.
A result below the interval may reflect low dietary intake, vitamin D deficiency, chronic kidney disease, or use of thiazide diuretics. If results do not match your situation, your clinician may repeat the collection, review the timing and completeness, or add confirmatory tests. Management may include adjusting diet and fluids, reviewing medicines, or treating an underlying condition.
Timed urine tests depend on accurate collection. Tell your care team if you missed any voids, spilled urine, or deviated from the schedule, because these issues can make results misleading.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Missing voids, spills, or incorrect start or end times can make the measured calcium falsely low or high. Discard the first void at the start, save all urine after that, include the final void at the end time, and keep the container as instructed.
High sodium or high animal protein intake can increase urinary calcium. Calcium and vitamin D supplements can raise excretion, while very low intake can lower it. Tell your clinician what you typically eat and which supplements you take.
Thiazide diuretics tend to lower urinary calcium, while loop diuretics can raise it. Other agents such as lithium, glucocorticoids, acetazolamide, and vitamin D analogs may affect results. Do not stop medicines without medical advice.
Low fluid intake and heavy sweating concentrate urine and can influence measured excretion. Aim to follow your usual fluid habits during the collection unless instructed otherwise.
Chronic kidney disease, malabsorption, celiac disease, bariatric surgery, and disorders that alter vitamin D metabolism can change urinary calcium handling. Share relevant medical history with your clinician.
Children, older adults, and pregnant individuals may handle calcium differently. Your clinician will interpret results in context and may use additional tests to clarify findings.
References