Calcium, Serum
This test measures the amount of calcium, a mineral essential for strong bones and healthy nerves, in your blood serum.
["Your blood calcium levels help ensure your body functions properly, including muscle and nerve activity."]
Key facts at a glance
- LOINC
- 16511-8
- Short code
- CALC9
- Synonyms
- Calcit sp9 p chal SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST)
- Units
- N/A
- Ref low
- 0
- Ref high
- 10
- Critical range
- — – 1000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–99 years
- Method
- Chemiluminescent Immunoassay (CLIA) or Radioimmunoassay (RIA)
- CPT
- 82308
- SNOMED
- 39565008
- Specimen volume
- 1-2 mL of serum per specimen; 9th specimen is the final timed collection in stimulation protocol
- Stability
- Serum stable at room temperature for 4 hours; refrigerated (2-8°C) for 24 hours; frozen at -20°C or below for up to 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 150
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Doctors may order a serum calcium test to check for conditions like low or high calcium levels, which can affect bones, muscles, or heart function. It’s often done if you have symptoms such as muscle spasms, confusion, or unusual fatigue, or if you have conditions like kidney disease, thyroid disorders, or osteoporosis.
What to Expect Before the Test
No special preparation is needed for this test. You’ll have a small needle inserted into your arm or vein to draw blood. It usually takes a few minutes, and you may feel a slight pinch or discomfort.
What the Results Mean
Results help determine if your calcium levels are within the normal range. Abnormal levels can signal underlying health issues that may require further evaluation or treatment.
Common Conditions Linked to Calcium Levels
Low calcium levels (hypocalcemia) may cause muscle cramps, numbness, or irregular heartbeat, while high levels (hypercalcemia) can lead to nausea, frequent urination, or kidney stones. Both conditions can be managed with lifestyle changes or medical treatment.
Reference range
Reference ranges vary by laboratory and assay methodology. For the 9th specimen post-calcium or pentagastrin stimulation challenge, peak calcitonin values are evaluated. Baseline serum calcitonin: males <10 pg/mL, females <5 pg/mL. Stimulated peak values vary; consult laboratory-specific reference ranges.N/A
No special fasting required. Patient should be informed about the stimulation test procedure. Baseline and timed specimens are collected following IV administration of stimulating agent (calcium gluconate or pentagastrin). Patient should remain recumbent during the test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Serum Calcium Level
Frequently asked questions
What causes changes in my calcium levels?
How often should I get this test?
Can diet affect my 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 14, 2026. · Read our editorial policy