Calcium, Serum (Mass Concentration)
This test measures the amount of calcium in your blood serum, which is important for many body functions, including muscle and nerve activity, bone health, and blood clotting.
["Calcium levels help assess bone health and overall mineral balance in your body."]
Key facts at a glance
- LOINC
- 12508-8
- Short code
- CALC4
- Synonyms
- Calcit sp4 p chal SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube without anticoagulant
- Units
- N/A
- Ref low
- 100
- Ref high
- 300
- Critical range
- — – 1000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–99 years
- Method
- Immunoassay (Chemiluminescent)
- CPT
- 82308
- SNOMED
- 39517004
- Specimen volume
- 1.0 mL serum
- Stability
- Serum stable for 8 hours at room temperature, 24 hours refrigerated at 2-8°C, and up to 3 months frozen at -20°C or colder
- Hemolysis max
- 100
- Lipemia max
- 500
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
Your doctor may order this test to help find out whether a certain condition is present, to check how well an organ is working, or to monitor how well a treatment you are already receiving is going.
Your healthcare provider may order this test to check for conditions like low or high calcium levels, which can cause symptoms such as muscle spasms, weakness, or irregular heartbeat. It may also be used to monitor conditions like kidney disease, bone disorders, or metabolic disorders.
Before the test, your care team will give you specific instructions to follow. You may be asked to avoid eating or drinking for several hours, stop taking certain medicines, or wear loose, comfortable clothing on the day of your visit.
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic panel, but this is not always required. Bring any medications you’re currently taking to your appointment.
During the test, a trained member of your care team will guide you through each step and explain what is happening along the way. The procedure is usually quick, and you can ask questions at any point if something feels unclear or uncomfortable.
A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but the procedure is quick and typically painless. The blood sample is then sent to a lab for analysis.
Your results may fall within the normal range, which usually means no signs of a problem were found, or outside the normal range, which can point to a condition that needs a closer look. Your doctor will review the report with you and explain what the findings mean for your health.
Results are compared to standard reference ranges, but your specific values will be discussed with your provider. Low calcium can lead to weakness or numbness, while very high levels may cause confusion or rapid heartbeat.
Reference range
Reference ranges for calcitonin stimulation tests are interpreted in the context of baseline and post-stimulation values. A peak calcitonin level exceeding 100 pg/mL in females or above 100-300 pg/mL in males post-calcium or pentagastrin stimulation is generally considered suggestive of medullary thyroid carcinoma. Reference values vary by laboratory, assay method, and stimulus used.N/A
Fasting is not required. Patient should remain supine for at least 15-30 minutes prior to specimen collection. For stimulation testing, the fourth specimen is collected at the designated time point after administration of the stimulating agent (calcium gluconate or pentagastrin).
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Calcium Levels Matter
Short name
Serum Calcium
Frequently asked questions
Low calcium (hypocalcemia) can weaken bones, cause muscle cramps, or increase the risk of kidney stones. High calcium (hypercalcemia) may lead to fatigue, nausea, or kidney problems. Both extremes can affect heart rhythm and bone health, so monitoring is key for conditions like osteoporosis, kidney disease, or thyroid disorders.
You can resume normal activities immediately. If you experienced bruising or discomfort at the injection site, apply a cold compress or take over-the-counter pain relievers as needed. Avoid heavy lifting or strenuous activity for a few hours.
Your provider will review your results with you and may recommend further testing or adjustments to your treatment plan, such as dietary changes, supplements, or medications. Follow-up may include additional blood tests or imaging if needed.
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 14, 2026. · Read our editorial policy