Calcium, Serum (Mass Concentration)
This test measures the amount of calcium in your blood serum, which is important for maintaining strong bones, proper muscle function, and nerve signaling.
["Your blood calcium levels help support healthy bones and vital bodily functions."]
Key facts at a glance
- LOINC
- 16507-6
- Short code
- CALC4HR
- Synonyms
- Calcit 4h p chal SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) - red/yellow speckled top, or plain red top tube. Plasma acceptable in lithium heparin or EDTA tubes.
- Units
- N/A
- Ref low
- 2
- Ref high
- 3
- Critical range
- — – 1000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–99 years
- Method
- Chemiluminescent Immunoassay (CLIA) or Electrochemiluminescent Immunoassay (ECLIA)
- CPT
- 82308
- SNOMED
- 104143002
- Specimen volume
- 1.0 mL serum or plasma (minimum 0.5 mL)
- Stability
- Room temperature: 4 hours; Refrigerated (2-8°C): 24 hours; Frozen (-20°C or below): 6 months. Avoid repeated freeze-thaw cycles. Store frozen for extended storage.
- Hemolysis max
- 100
- Lipemia max
- 500
- Icterus max
- 25
- 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 also used to diagnose or monitor kidney disease, thyroid disorders, or metabolic bone diseases.
What Does the Test Involve?
You’ll have a small needle inserted into your arm to draw blood. The blood sample is then sent to a lab for analysis using a specialized chemical method to measure calcium concentration.
What Are Common Causes of Abnormal Results?
Low calcium (hypocalcemia) may be linked to vitamin D deficiency, kidney problems, or certain medications. High calcium (hypercalcemia) could result from overactive thyroid, bone diseases, or prolonged exposure to sunlight.
How Will I Know If My Results Are Within Normal Limits?
Your doctor will compare your results to standard reference ranges specific to your age, gender, and overall health. They’ll discuss any deviations and next steps with you.
Reference range
Post-calcium stimulation test reference ranges are interpreted in conjunction with baseline values; a stimulated calcitonin level exceeding 100 pg/mL (or >2-3x baseline) is suggestive of medullary thyroid carcinoma (MTC). Pentagastrin-stimulated calcitonin peak >100 pg/mL in males and >50 pg/mL in females is considered abnormal. Calcium-stimulated peak values are laboratory-specific.N/A
Fasting is not required. Patient should remain supine for at least 30 minutes prior to collection. Stimulation procedure (calcium gluconate IV infusion typically 2 mg/kg over 1 minute) must be coordinated with the laboratory. Document the exact time of stimulus administration.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Serum Calcium
Frequently asked questions
What does a serum calcium test measure exactly?
How often should I get this test if I have no symptoms?
Can diet or supplements 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 15, 2026. · Read our editorial policy