Calcium4hurmrate
A test that measures the amount of calcium excreted in urine over a 4-hour period to help diagnose kidney stones and calcium metabolism disorders.
{"This test measures calcium levels in urine collected over 4 hours","It helps diagnose kidney stones and parathyroid disorders","Abnormal results may indicate hyperparathyroidism, kidney disease, or certain medications","Collection requires a 4-hour urine sample, usually in the morning","Results are reported as milligrams of calcium per 4 hours (mg/4hr)"}
Key facts at a glance
- LOINC
- 27091-8
- Short code
- CAU4H
- Synonyms
- Calcium 4h Ur-mRate
- Category
- electrolyte
- Sample
- urine
- Container
- Sterile urine collection container (plastic or glass)
- Units
- not specified
- Ref low
- 10
- Ref high
- 40
- Critical range
- 6 not specified – 14 not specified
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Spectrophotometry (Arsenazo III or o-cresolphthalein complexone method)
- CPT
- 82340
- SNOMED
- 365761006
- Specimen volume
- Minimum 10 mL; complete 4-hour collection preferred
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 30 days
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
What is this test?
The 4-hour urine calcium test measures how much calcium your kidneys excrete in your urine over a 4-hour period. Calcium is an essential mineral that plays crucial roles in bone health, muscle function, and nerve signaling. Normally, your body carefully balances calcium levels by absorbing it from food, storing it in bones, and excreting excess amounts through urine.
How is the test performed?
You will be given a special container to collect all urine produced during a 4-hour period, typically in the morning. It's important to: (1) Collect your first morning urine and note the time, (2) Collect all subsequent urine for the next 4 hours into the provided container, (3) Keep the sample refrigerated or on ice during collection, (4) Return the complete sample to your healthcare provider as instructed. Sometimes you may be asked to follow a specific diet or fast before the test.
Why might I need this test?
Your doctor may order this test if you have symptoms of kidney stones (severe back or abdominal pain, blood in urine), signs of hyperparathyroidism (fatigue, weakness, depression), or abnormal blood calcium levels. It is also used to monitor patients with known calcium metabolism disorders or those taking medications that affect calcium levels.
What do the results mean?
Normal urine calcium levels typically range from 100 to 300 mg per 24 hours (or proportionally less for a 4-hour sample). High urine calcium (hypercalciuria) may indicate kidney stones, hyperparathyroidism, sarcoidosis, vitamin D excess, or certain cancers. Low urine calcium (hypocalciuria) may be seen in hypoparathyroidism, vitamin D deficiency, or chronic kidney disease. Your doctor will interpret your results based on your overall health and other test findings.
Are there any risks?
This test carries no physical risks. The main considerations are: (1) Collecting all urine during the 4-hour period for accurate results, (2) Properly storing the sample to prevent bacterial growth, (3) Informing your doctor about all medications you are taking, as some drugs can affect calcium levels.
Reference range
10-40 mg/4 h (laboratory-specific; approx. based on 24 h norms)not specified
Exact timed 4-hour urine collection required (empty bladder at start, collect all urine thereafter); often after overnight fast; follow any protocol-specific diet restrictions (e.g., avoid high-calcium foods/supplements)
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Do I need to fast before the 4-hour urine calcium test?
Can I exercise before the test?
What medications can affect urine calcium levels?
How long does it take to get results?
What happens if my urine calcium is high?
Sources
- 1
- 2
- 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