Calcium, Serum or Plasma (Mass Concentration)
This test measures the amount of calcium in your blood, which is important for keeping bones strong, muscles working properly, and nerves functioning correctly.
["Your blood calcium levels help ensure healthy bones, muscle contractions, and nerve signals."]
Key facts at a glance
- LOINC
- 16508-4
- Short code
- CALC5
- Synonyms
- Calcit 5M 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
- 11.5
- Critical range
- — – 1000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Chemiluminescent Immunoassay (CLIA) or Radioimmunoassay (RIA)
- CPT
- 82308
- SNOMED
- 39571007
- Specimen volume
- 1 mL serum
- Stability
- Room temperature: 2 hours; Refrigerated (2-8°C): 24 hours; Frozen (-20°C or below): 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order a calcium test to check for conditions like low or high calcium levels, which can affect your bones, heart, or muscles. It might also be done to monitor certain treatments or medical conditions, such as kidney disease, bone disorders, or thyroid issues.
What to Expect During the Test
A blood sample is taken from a vein in your arm, usually by a healthcare professional. You may feel a slight pinch, but it usually doesn’t cause discomfort. The sample is then sent to a lab for testing.
Possible Causes of Abnormal Results
Low calcium levels (hypocalcemia) can be caused by conditions like vitamin D deficiency, kidney problems, or certain medications. High calcium levels (hypercalcemia) may result from overactive thyroid, bone diseases, or prolonged immobilization.
What the Results Mean
While specific ranges vary by lab, abnormal results may prompt further testing or adjustments to your treatment plan. Your doctor will discuss findings with you based on your overall health.
Reference range
Interpretation requires comparison with baseline (pre-challenge) calcitonin level. A stimulated calcitonin level exceeding 100 pg/mL is highly suggestive of medullary thyroid carcinoma (MTC). Gender-specific baseline ranges: Males <11.5 pg/mL; Females <5.0 pg/mL. Provocative testing thresholds vary by challenge agent (calcium gluconate or pentagastrin).N/A
No special fasting required. Patient should be supine for at least 15 minutes prior to specimen collection. Baseline specimen must be drawn before administering the challenge agent (calcium gluconate or pentagastrin). Inform clinician of all medications, particularly proton pump inhibitors and beta-blockers which may affect calcitonin levels.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Calcium is a vital mineral that plays a critical role in bone health, muscle function, nerve signaling, and blood clotting. Persistently low or high levels can indicate underlying health issues requiring medical attention.
Short name
Calcium Level
Frequently asked questions
What does a calcium test measure?
Can diet affect my calcium test results?
How often should I get this test?
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