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Serum Calcium (Total)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of calcium present in your blood serum, which is important for maintaining healthy bones, muscles, nerves, and other body functions.

Quick summary

["Your blood calcium levels help support strong bones and proper nerve/muscle function."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
37654-1
Short code
XR Scapula 1V
Synonyms
XR Scapula 1V
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order a total serum calcium test to check for conditions like low or high calcium levels, which can affect bones, heart rhythm, or muscle function. It might also be used to monitor treatment for conditions such as osteoporosis, kidney disease, or hyperparathyroidism.

What Does the Test Involve?

A blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab for analysis. Calcium levels are measured using a blood chemistry test that detects the total amount of calcium in your serum.

What Are Common Causes of Abnormal Results?

Low calcium levels (hypocalcemia) can occur due to conditions like vitamin D deficiency, kidney problems, or certain medications. High calcium levels (hypercalcemia) may result from overactive thyroid, cancer, or prolonged bed rest.

How Is This Test Different from Other Calcium Tests?

This test measures total calcium, which includes both ionized (active) and bound calcium. Ionized calcium is the form that directly affects your body’s functions, so additional tests may be needed to assess this specific form if needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Total Serum Calcium

Frequently asked questions

What might my doctor ask about before the test?
Your doctor may ask about recent medications, dietary habits (especially calcium and vitamin D intake), known conditions like kidney disease or thyroid disorders, and any symptoms such as muscle cramps, fatigue, or bone pain.
How long will it take to get my results?
Results are typically available within 1 to 3 business days, depending on your lab. Your doctor will discuss the findings with you during a follow-up visit.
Can I eat or drink anything before this test?
You can usually eat and drink normally before this test unless instructed otherwise by your doctor. Some tests may require fasting, but this is not the case for serum calcium.
  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 16, 2026. · Read our editorial policy