Serum Calcium Concentration (with 24-Hour Collection Qualifier)
This test measures the amount of calcium in your blood serum over a 24-hour period. Calcium is an essential mineral that helps with muscle and nerve function, bone health, and blood clotting.
["Understanding your 24-hour calcium levels helps doctors assess long-term mineral balance and identify potential deficiencies or excesses over time."]
Key facts at a glance
- LOINC
- 79367-9
- Short code
- XR Sacrum+Coccyx GE 2V
- Synonyms
- XR Sacrum+Coccyx GE 2V
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 20
- Ref high
- 400
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- xr
- CPT
- 82670
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like muscle weakness, bone pain, or unusual fatigue. It could also be used to monitor conditions such as kidney disease, vitamin D deficiency, or metabolic bone disorders. Rarely, it may be part of a broader evaluation for unexplained calcium imbalances or chronic conditions like hyperparathyroidism.
What to Expect Before the Test
No special preparation is needed for this test. You may have a blood draw at a clinic or lab, and the serum portion will be collected for analysis. If you’re taking calcium supplements or certain medications, let your provider know, as they may affect results.
What the Results Mean
Calcium levels in blood can fluctuate based on diet, hydration, and health status. A 24-hour collection helps provide a more accurate picture of your body’s calcium handling. Results are typically reported as a concentration value, but your doctor will interpret them in the context of your overall health.
Common Causes of Abnormal Results
Low calcium levels (hypocalcemia) can occur due to vitamin D deficiency, kidney problems, or certain medications. High calcium levels (hypercalcemia) may result from overactive thyroid, bone diseases, or prolonged vitamin A exposure. Both extremes can cause serious health issues if untreated.
Reference range
Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Serum Calcium (24h)
Frequently asked questions
How long does it take to get my test results back?
Can I eat or drink anything before this test?
What if my calcium levels are out of the normal range?
Sources
- 1
- 2Lab Tests OnlineSource
- 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