Calcium, Serum or Plasma (Mass Concentration)
This test measures the amount of calcium in your blood, which is important for strong bones, healthy nerves, and proper muscle function.
["Checks your blood calcium levels for health or potential issues like bone disorders or other conditions."]
Key facts at a glance
- LOINC
- 107499-6
- Short code
- CALC20
- Synonyms
- Calcit 20M p chal SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST)
- Units
- N/A
- Critical range
- — – 1000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Immunoassay (Chemiluminescent or Electrochemiluminescent)
- CPT
- 82308
- SNOMED
- 39565006
- Specimen volume
- 1.0 mL serum (minimum 0.5 mL)
- Stability
- Room temperature: 2 hours; Refrigerated (2-8°C): 24 hours; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why It’s Done
Your doctor may order this test if you have symptoms like muscle cramps, fatigue, or unusual bone pain. It’s also used to monitor conditions like osteoporosis, kidney disease, or hyperparathyroidism. Some people get it as part of a routine check or before certain treatments.
What to Expect
A small needle is used to draw blood from a vein in your arm. The process takes about 5 minutes. You may feel a slight pinch, but it usually doesn’t cause pain. The blood sample is sent to a lab for testing.
What the Results Mean
Calcium levels can vary based on diet, health conditions, and medications. While reference ranges differ by lab, low or high levels may signal underlying health concerns that need further evaluation.
Common Causes of Abnormal Results
Low calcium (hypocalcemia) might be due to vitamin D deficiency, kidney problems, or certain medications. High calcium (hypercalcemia) could result from overactive thyroid, bone diseases, or prolonged bed rest.
Reference range
Reference ranges for calcitonin post-stimulation challenge vary by laboratory and assay methodology. Typically, a peak calcitonin level >100 pg/mL in females or >150 pg/mL in males following pentagastrin or calcium stimulation is suggestive of medullary thyroid carcinoma (MTC). Consult the performing laboratory's reference values.N/A
No special fasting required. Patient should remain supine for at least 15 minutes prior to and during specimen collection. The stimulating agent (pentagastrin or calcium gluconate) must be administered as per the stimulation protocol prior to the 20-minute post-challenge specimen draw.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Calcium Level
Frequently asked questions
Why might my doctor ask for this test?
What if my calcium level is too low or too high?
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