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, bone health, and blood clotting.
["Your calcium levels help ensure strong bones, proper muscle function, and healthy blood clotting."]
Key facts at a glance
- LOINC
- 51430-7
- Short code
- CT-PREPOST
- Synonyms
- Calcit pre/p chal SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube; Plasma may use EDTA or heparin tubes per laboratory protocol
- Units
- N/A
- Ref low
- 0
- Ref high
- 10
- Critical range
- — – 1000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (Chemiluminescent or Radioimmunoassay)
- CPT
- 82308
- SNOMED
- 39521008
- Specimen volume
- 1.0-2.0 mL of serum or plasma; minimum 0.5 mL
- Stability
- Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days; Avoid repeated freeze-thaw cycles
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 24–96 hours
- Order
- routine
Why Is This Test Done?
Doctors may order a calcium test to check for conditions like low or high calcium levels (hypocalcemia or hypercalcemia), bone diseases, kidney problems, or metabolic disorders. It can also be part of routine health checks or when symptoms like muscle cramps, fatigue, or frequent fractures appear.
What to Expect During the Test
A small blood sample is taken from a vein, usually in your arm. You may feel a slight pinch, but it’s quick and doesn’t require special preparation. The sample is sent to a lab for analysis.
Possible Causes of Abnormal Results
Low calcium levels might be due to conditions like vitamin D deficiency, kidney disease, or certain medications. High levels could result from overactive thyroid, cancer, or prolonged immobilization. Your doctor will discuss these with you based on your symptoms and other test results.
What You Should Know Before Testing
No special preparation is needed, but inform your doctor about any medications (like calcium supplements or certain blood pressure drugs) or health conditions you have. Avoid drinking large amounts of calcium-rich foods or supplements right before testing if instructed.
Reference range
Basal: <10 pg/mL (male), <5 pg/mL (female); Pentagastrin-stimulated peak varies by clinical context; Calcium-stimulated peak: <100 pg/mL (males), <70 pg/mL (females)N/A
No special preparation required for basal sample. For stimulation testing, patient should fast overnight (8-12 hours). Discontinue calcium supplements 24 hours prior if calcium stimulation is used. Avoid biotin supplements for at least 72 hours before testing as biotin may interfere with immunoassays.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Calcium Level
Frequently asked questions
How does calcium affect my overall health?
What if my calcium level is out of range?
Can diet affect calcium test 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 15, 2026. · Read our editorial policy