Understanding Your Diagnostic Test: Purpose, Procedure, Results, and Safety
A test that measures the amount of calcium in your urine collected over one hour to evaluate calcium metabolism and kidney function.
{"Measures calcium levels in urine collected over 1 hour","Helps diagnose kidney stones and calcium metabolism disorders","Results are reported in moles per time (mmol/hour)","Requires a specific urine collection procedure","May need dietary preparation before the test"}
Key facts at a glance
- LOINC
- 53124-4
- Short code
- CAU1HR
- Synonyms
- Calcium 1h Ur-sRate
- Category
- electrolyte
- Sample
- urine
- Container
- Clean, labeled plastic urine container (no preservative needed for short collections)
- Units
- not specified
- Ref low
- 0.1
- Ref high
- 0.3
- Critical range
- 6 not specified – 14 not specified
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–100 years
- Method
- Colorimetric (Arsenazo III) or Atomic Absorption Spectrometry (AAS)
- CPT
- 82340
- SNOMED
- 104435004
- Specimen volume
- Complete timed collection, minimum 10 mL aliquot for analysis
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 72 hours; Frozen (-20°C): 2 weeks
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test? This diagnostic test is used to evaluate a specific aspect of your health, help identify possible medical conditions, or monitor how well treatment is working.
The 1-Hour Urine Calcium test measures how much calcium your kidneys are excreting in your urine over a one-hour period. Calcium is an essential mineral important for bone health, muscle function, and nerve signaling. This test helps doctors understand how your body processes calcium and how well your kidneys are working.
How is the test performed? Depending on the test, a healthcare professional may collect blood, urine, tissue, or another sample, or use imaging equipment while explaining each step.
You will be asked to collect all urine produced during a one-hour period into a special container provided by the lab. It's important to collect the entire sample without missing any urine during that time. The sample should be kept cool if not delivered to the lab immediately. Your healthcare provider may ask you to fast overnight or follow a specific diet before the test.
What do the results mean? Your healthcare professional will interpret the results in context, considering your symptoms, medical history, medications, and reference ranges rather than relying on one value alone.
Results are reported in millimoles per hour (mmol/hour). Higher than normal urine calcium levels (hypercalciuria) may indicate kidney stones, hyperparathyroidism, certain bone disorders, or excessive vitamin D intake. Lower than normal levels (hypocalciuria) may suggest kidney disease, hypoparathyroidism, or vitamin D deficiency. Your doctor will interpret your results based on your overall health and other test results.
Are there any risks? Most diagnostic tests are safe, although some may cause temporary discomfort, bruising, dizziness, irritation, or other minor effects; your care team can explain test-specific risks.
This test involves only urine collection and carries no significant risks. Some people may find it inconvenient to collect urine for a full hour, especially when away from home. Follow all collection instructions carefully to ensure accurate results.
Reference range
0.1-0.3 mmol/hnot specified
Timed 1-hour urine collection required; no fasting typically needed but avoid calcium supplements and maintain usual diet unless directed otherwise for specialized testing
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The 1-Hour Urine Calcium test is primarily used to evaluate calcium metabolism disorders. It helps diagnose the cause of kidney stones, as high calcium in urine is a major risk factor for stone formation. The test is also useful in monitoring patients with hyperparathyroidism, bone diseases, and certain kidney disorders. Additionally, it can help assess response to treatment for conditions that affect calcium levels in the body.
Frequently asked questions
Do I need to prepare for this test?
Will the test be painful?
How long does it take to get results?
What happens if my results are abnormal?
Sources
- 1
- 2Mayo Clinic - UrinalysisSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy