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Calciumserplscnc

Published: July 31, 2026Updated: August 10, 2026

A blood test that measures the amount of calcium in your blood to evaluate bone health, nerve function, and muscle function.

Quick summary

{"Measures calcium levels in your blood using a simple blood draw","Helps diagnose conditions affecting bones, kidneys, parathyroid glands, and nerves","Abnormal results may indicate hypercalcemia (high calcium) or hypocalcemia (low calcium)","Often part of routine health checkups or when symptoms like weakness or confusion are present","Fasting is usually not required, but follow your doctor's instructions"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 10, 2026Editorial policy

Key facts at a glance

LOINC
2000-8
Short code
CA
Synonyms
Calcium SerPl-sCnc
Category
electrolyte
Sample
serum
Container
Serum separator tube (SST/Gold top) 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
Colorimetric (o-cresolphthalein complexone) or Ion-Selective Electrode (ISE)
CPT
82310
SNOMED
271587001
Specimen volume
2-5 mL of whole blood
Stability
Room temperature: 2-3 days; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 3 months
Hemolysis max
50
Lipemia max
300
Icterus max
20
TAT
1–4 hours
Order
routine

What is a Serum Calcium Test?

A serum calcium test measures the concentration of calcium in the liquid part of your blood (serum). Calcium is an essential mineral that plays a vital role in building strong bones and teeth, helping muscles contract, enabling nerves to send signals, and supporting blood clotting. This test uses the LOINC code 2000-8 and is classified as an electrolyte panel test.

Why Do I Need This Test?

Your doctor may order a calcium test to: check your overall health as part of a routine blood test, investigate symptoms like fatigue, muscle cramps, weakness, or confusion, monitor conditions affecting calcium levels such as kidney disease, parathyroid disorders, or bone diseases, or evaluate the effectiveness of calcium or vitamin D supplements.

How Is the Test Performed?

A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The procedure only takes a few minutes and is generally well-tolerated. The blood sample is then sent to a laboratory for analysis. You typically do not need to fast before this test, though your doctor may provide specific instructions.

What Do My Results Mean?

Normal calcium levels typically range from 2.1 to 2.6 mmol/L (8.5 to 10.5 mg/dL). However, the exact normal range may vary slightly depending on the laboratory. Your doctor will interpret your results based on your overall health, symptoms, and other test results. Both high and low calcium levels can indicate underlying health problems that require further investigation.

Reference range

2.15-2.55 mmol/Lnot specified

Specimen: serum

No fasting required; avoid calcium supplements for 8-12 hours prior if possible

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings3

Frequently asked questions

Do I need to fast before a calcium blood test?
Fasting is typically not required for a serum calcium test. However, always follow your healthcare provider's specific instructions, as they may recommend fasting if other tests are being performed at the same time.
What are the normal calcium levels in blood?
Normal total calcium levels are typically between 2.1 and 2.6 mmol/L (8.5 to 10.5 mg/dL). The normal range may vary slightly between laboratories. Your doctor will explain your results in the context of your overall health.
Can medications affect calcium test results?
Yes, certain medications can affect calcium levels. These include diuretics, antacids containing calcium or aluminum, lithium, and certain chemotherapy drugs. Inform your doctor about all medications and supplements you are taking before the test.
Is the calcium test dangerous?
The risks are minimal and similar to any routine blood draw. You may experience slight bruising, bleeding, or dizziness at the injection site. These side effects are usually temporary and resolve quickly.
What happens if my calcium levels are abnormal?
If your calcium levels are abnormal, your doctor will likely order additional tests to determine the cause. These may include tests for parathyroid hormone (PTH), vitamin D, kidney function, or imaging studies. Treatment depends on the underlying cause and may include medication, dietary changes, or other interventions.
  1. 1
    MedlinePlus - Calcium Blood TestSource
  2. 2
    Mayo Clinic - Calcium TestSource
  3. 3
    Lab Tests Online - CalciumSource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

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