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Serum or plasma calcium concentration (total)

Published: August 9, 2026Updated: August 14, 2026

This test measures the amount of calcium in your blood, which is important for keeping your bones strong, muscles working properly, and nerves functioning correctly.

Quick summary

["Your blood calcium level helps ensure healthy bones, muscle function, and nerve signals."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 14, 2026Editorial policy

Key facts at a glance

LOINC
16509-2
Short code
CALCIT7
Synonyms
Calcit sp7 p chal SerPl-mCnc
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top vacutainer tube
Units
N/A
Ref low
0
Ref high
100
Fasting
false
Population
adult
Sex
all
Age range
≥ 18 years
Method
Chemiluminescent Immunoassay (CLIA) / Immunochemiluminometric Assay (ICMA)
CPT
82308
SNOMED
103152001
Specimen volume
1.0-2.0 mL serum
Stability
Serum stable for 8 hours at room temperature (15-25°C); 24 hours refrigerated at 2-8°C; up to 3 months frozen at -20°C or lower. Avoid repeated freeze-thaw cycles.
Hemolysis max
100
Lipemia max
500
Icterus max
20
TAT
24–72 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 spasms, weakness, or irregular heartbeat. It’s also used to monitor conditions like kidney disease, bone disorders, or metabolic issues that affect calcium balance.

What Does the Result Mean?

Results can indicate whether your body is absorbing calcium properly, if you have conditions affecting bone health, or if there’s an imbalance in minerals like magnesium or phosphorus that might influence calcium levels.

Common Conditions Monitored

This test is often used to diagnose or monitor conditions such as hypoparathyroidism (low thyroid hormone affecting calcium), hyperparathyroidism (overactive thyroid gland), kidney disease, or vitamin D deficiency, which can all impact calcium levels.

Sample Collection and Preparation

A blood sample is drawn from a vein, usually in your arm. The blood is then processed into either serum (liquid after clotting) or plasma (liquid after anticoagulant use) for testing. Avoiding certain foods or supplements (like calcium-rich foods or vitamin D) for 24 hours before the test may help provide more accurate results.

Reference range

Basal calcitonin reference ranges vary by laboratory and assay method. Following provocative stimulation, peak calcitonin levels are evaluated; a peak value <100 pg/mL (males) or <120 pg/mL (females) is generally considered normal, while values >100 pg/mL in males or >120 pg/mL in females suggest medullary thyroid carcinoma (MTC). Reference ranges must be interpreted in context of the specific stimulation test protocol.N/A

Specimen: serum

Fasting is not required. Patient should be informed about the nature of the provocative stimulation test (e.g., pentagastrin or calcium infusion). Obtain 7th timed specimen following administration of stimulating agent. No special dietary restrictions unless specified by stimulation protocol. Inform clinician of all medications, including proton pump inhibitors, which may affect calcitonin levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Total Calcium Level

Frequently asked questions

What causes my calcium level to be checked?
Your doctor may recommend this test if you have symptoms like muscle cramps, frequent bone fractures, unusual fatigue, or if they suspect an underlying condition affecting calcium metabolism, such as kidney disease, thyroid issues, or vitamin deficiencies.
How soon will I get my results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the findings with you during your follow-up visit.
Can I eat or drink anything before this test?
For most calcium tests, you can eat and drink normally, but avoid high-calcium foods (like dairy) or large amounts of vitamin D supplements for 24 hours before testing to help ensure accurate results.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

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 14, 2026. · Read our editorial policy