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Serum Calcium (Total)

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

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

Quick summary

["Calcium levels help your body function properly, from bone strength to nerve signals."]

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

Key facts at a glance

LOINC
103475-0
Short code
XR Scapula-R 1V
Synonyms
XR Scapula-R 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?

Your doctor may order this test to check for conditions like low or high calcium levels, which can cause symptoms such as muscle cramps, weakness, or abnormal heart rhythms. It may also be used in monitoring treatments for conditions like kidney disease or osteoporosis.

What to Expect Before the Test

You can eat and drink normally before this test. No special preparation is needed unless your doctor instructs otherwise. Bring any medications you’re currently taking to your appointment.

During the Test

A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch, but the process is quick and usually painless. You’ll be able to go about your day afterward.

Possible Results and Interpretation

Results are compared to standard ranges, but exact values can vary by lab. Low calcium may suggest conditions like vitamin D deficiency or kidney issues, while high levels could indicate overactive thyroid or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Total Serum Calcium

Frequently asked questions

What causes low calcium levels?
Low calcium can result from dietary deficiencies (e.g., lack of vitamin D or calcium), kidney problems, or certain medications. It may also occur after surgery or during pregnancy.
What causes high calcium levels?
High calcium levels can be caused by overactive thyroid, kidney disease, or certain cancers. Long-term use of some medications or excessive vitamin D intake can also lead to elevated levels.
How often should I get this test?
Frequency depends on your health status. Your doctor will determine how often you need this test based on your medical history, symptoms, and any ongoing treatments.
  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