Calcium, Serum or Plasma, Mass Concentration
This test measures the amount of calcium in your blood, which is important for many body functions, including muscle and nerve activity.
["Your calcium levels help ensure strong bones, proper muscle function, and healthy nerve signals."]
Key facts at a glance
- LOINC
- 16506-8
- Short code
- CALC3HR
- Synonyms
- Calcit 3h p chal SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST)
- Units
- N/A
- Ref low
- 0
- Ref high
- 10
- Critical range
- 20 N/A – 400 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (Chemiluminescent or Radioimmunoassay)
- CPT
- 82308
- SNOMED
- 395940009
- Specimen volume
- 1 mL serum
- Stability
- Serum is stable for 8 hours at room temperature, 24 hours at 2-8°C, and up to 30 days at -20°C or colder. For prolonged storage, freeze at -70°C.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Doctors may order a calcium test to check for conditions like low or high calcium levels, which can affect bones, muscles, or heart function. It might also be done if you have symptoms such as muscle spasms, confusion, or unusual fatigue.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it involves a blood draw, but this depends on your doctor’s instructions. Bring any medications you’re currently taking.
How the Test Is Done
A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it’s usually over quickly. The blood sample is sent to a lab for analysis.
What the Results Mean
Results are reported in milligrams per deciliter (mg/dL). Low calcium can cause weakness or numbness, while high levels may lead to kidney stones or irregular heart rhythms. Your doctor will interpret results based on your overall health.
Reference range
Reference values vary by stimulation test and laboratory method. Generally, basal calcitonin in adults is <10 pg/mL (males) and <5 pg/mL (females). Post-challenge peak values depend on the provocative agent used; typically a rise >100 pg/mL in males or >50 pg/mL in females is suggestive of medullary thyroid carcinoma.N/A
No special patient preparation is typically required. Patient should remain supine for at least 15 minutes prior to and during specimen collection. Information regarding the specific provocative agent administered (e.g., calcium, pentagastrin) should be documented with the specimen.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal calcium levels can signal underlying issues like kidney disease, thyroid disorders, or conditions affecting bone metabolism. Chronic imbalances may require treatment to prevent long-term damage to organs or nerves.
Short name
Calcium Level
Frequently asked questions
What causes low calcium levels?
What causes high calcium levels?
How long does it take to get results?
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 17, 2026. · Read our editorial policy