Serum Calcium (Total)
This test measures the amount of calcium in your blood serum. Calcium is an essential mineral that helps with muscle and nerve function, bone health, and blood clotting.
["Your blood calcium levels help your body stay strong and function properly."]
Key facts at a glance
- LOINC
- 50474-6
- Short code
- CALC6
- Synonyms
- Calcit sp6 SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube; plasma may be collected in EDTA or heparin tubes
- Units
- N/A
- Ref low
- 0
- Ref high
- 11.5
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Chemiluminescent Immunoassay (CLIA) or Electrochemiluminescence Immunoassay (ECLIA)
- CPT
- 82308
- SNOMED
- 103225008
- Specimen volume
- 1.0 mL of serum or plasma; minimum 0.5 mL
- Stability
- Serum/plasma stable for 8 hours at room temperature, 24 hours at 2-8°C, and up to 6 months frozen at -20°C or colder. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 25
- TAT
- 4–48 hours
- Order
- routine
Why Is This Test Done?
Doctors may order this test to check for conditions like low or high calcium levels, which can cause symptoms such as muscle cramps, weakness, or abnormal heart rhythms. It may also be done to diagnose or monitor diseases like osteoporosis, kidney problems, or certain cancers.
What Does the Test Involve?
A blood sample is taken from a vein, usually in your arm. You may feel a small pinch when the needle is inserted, but the procedure is quick. The blood sample is sent to a lab for analysis.
What Are Common Causes of Abnormal Results?
Low calcium levels (hypocalcemia) can result from conditions like vitamin D deficiency, kidney disease, or certain medications. High calcium levels (hypercalcemia) may be linked to overactive thyroid, certain cancers, or prolonged exposure to sunlight.
How Is the Test Performed?
The test uses a chemical method to measure the total calcium in your blood serum. No special preparation is usually needed, but you should inform your doctor about any medications you’re taking.
Reference range
Reference values vary by laboratory, assay method, age, and sex. Males typically have higher baseline values than females. Generally: Males <11.5 pg/mL; Females <5.0 pg/mL (pentagastrin-stimulated peak varies). For the 6th specimen in a stimulation series, results should be interpreted in the context of the full dynamic testing protocol.N/A
No special preparation required for basal calcitonin. For stimulation testing, patient should fast for at least 8 hours prior to testing. Pentagastrin or calcium stimulation tests require physician supervision due to potential adverse effects including flushing, nausea, and abdominal cramping.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Total Serum Calcium
Frequently asked questions
What are the normal reference ranges?
Do I need to prepare for this test?
Can I eat or drink before the 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 14, 2026. · Read our editorial policy