Medical Test Overview: This test may help a health care professional check how the body is working and guide symptom assessment, treatment, and monitoring decisions.
A blood test that measures the amount of calcium in your serum to evaluate bone health, nerve function, and heart health.
{"Measures calcium level in your blood using a serum sample","Helps diagnose bone diseases, nerve problems, and heart conditions","Normal range is typically 2.1-2.6 mmol/L (8.5-10.5 mg/dL)","Abnormal results may indicate kidney disease, parathyroid disorders, or vitamin D deficiency","Fasting is usually not required, but follow your doctor's instructions"}
Key facts at a glance
- LOINC
- 32305-5
- Short code
- CA
- Synonyms
- Calcium Spec-sCnc
- Category
- electrolyte
- Sample
- serum
- Container
- Serum separator tube (SST) or plain red top tube
- Units
- not specified
- Ref low
- 2.15
- Ref high
- 2.55
- Critical range
- 1.5 not specified – 3.25 not specified
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Spectrophotometry (Arsenazo III method) or Ion-Selective Electrode (ISE) or Atomic Absorption Spectrophotometry (AAS)
- CPT
- 82310
- SNOMED
- 271560004
- Specimen volume
- 1.0 mL serum minimum
- Stability
- Room temperature: 7 days; Refrigerated (2-8°C): 14 days; Frozen (-20°C): 30 days
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 1–24 hours
- Order
- routine
What is this test, and what information does it provide about how a body system is working so that a health care professional can understand the health condition of a patient and decide on next steps?
The Blood Calcium Test measures the amount of calcium in the liquid part of your blood (serum). Calcium is an essential mineral that plays a crucial role in building strong bones and teeth, helping muscles contract, enabling nerves to transmit signals, and supporting heart function.
Why do I need this test, and how might the results help my health care professional understand my symptoms, assess my risk, guide treatment choices, and monitor my progress over time?
Your doctor may order a calcium blood test to: check for bone diseases such as osteoporosis; evaluate parathyroid gland function; monitor kidney disease; investigate symptoms like muscle cramps, weakness, or numbness; assess heart rhythm problems; or monitor calcium levels if you are taking calcium supplements or vitamin D supplements.
How is this test performed, what should I expect during the appointment, and how is a sample or measurement collected safely by a trained health care team to protect my privacy and comfort?
A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The blood is collected into a tube and sent to a laboratory for analysis. The procedure only takes a few minutes and is generally well-tolerated.
How should I prepare for this test, and what instructions may my health care team give me about food, drinks, medicines, activity, or other steps I should take before the appointment?
Fasting is usually not required for a calcium blood test. However, inform your doctor about all medications, supplements, and vitamins you are taking, as some can affect calcium levels. Follow any specific instructions given by your healthcare provider.
Reference range
2.15-2.55 mmol/Lnot specified
No fasting required; avoid prolonged tourniquet use
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
High calcium levels (hypercalcemia) may indicate: hyperparathyroidism, cancer, vitamin D overdose, kidney disease, or certain medications. Symptoms may include fatigue, nausea, constipation, confusion, and kidney stones.
Low calcium levels (hypocalcemia) may indicate: vitamin D deficiency, hypoparathyroidism, kidney failure, pancreatitis, or certain infections. Symptoms may include muscle cramps, numbness in fingers and toes, seizures, and irregular heartbeat.
Reference range typically: 2.1-2.6 mmol/L (8.5-10.5 mg/dL). Values may vary slightly between laboratories. Your doctor will interpret your results based on your overall health and other test results.
Frequently asked questions
Does the test hurt?
How long does it take to get results?
Are there any risks with this test?
Can I eat before the test?
What happens if my calcium is abnormal?
Sources
- 1
- 2
- 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 10, 2026. · Read our editorial policy