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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, nerves, and overall body function.

Quick summary

["Check your calcium levels to support bone health and prevent potential deficiencies or imbalances."]

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

Key facts at a glance

LOINC
36645-0
Short code
XR Clavicle 2V
Synonyms
XR Clavicle 2V
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
20
Ref high
400
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
CPT
82670
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 healthcare provider may order this test to diagnose or monitor conditions like hypocalcemia (low calcium) or hypercalcemia (high calcium), assess kidney function, or evaluate symptoms such as muscle cramps, fatigue, or abnormal heart rhythms.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic panel. Bring any medications you’re currently taking to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure is quick and typically painless. The blood sample is then sent to a lab for analysis.

What Are Possible Results?

Results are reported in milligrams per deciliter (mg/dL). While reference ranges vary slightly by lab, typical values for adults usually fall between 8.4 and 10.2 mg/dL. Your results will be interpreted by your healthcare provider in the context of your overall health.

Reference range

Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Total Serum Calcium

Frequently asked questions

How Does This Test Help Healthcare Providers?
Low calcium levels (hypocalcemia) may indicate conditions like vitamin D deficiency, kidney disease, or certain medications. High calcium levels (hypercalcemia) could signal hyperparathyroidism, cancer, or other metabolic disorders. Regular monitoring helps manage these conditions effectively.
What If My Results Are Out of Range?
If your calcium levels are outside the normal range, your provider may recommend further testing, such as checking vitamin D, parathyroid hormone, or kidney function. Lifestyle adjustments (like diet or supplements) may also be suggested to help balance levels.
Can I Eat or Drink Before This Test?
If fasting is required (e.g., for a metabolic panel), avoid food and liquids except water for 8–12 hours before the test. If fasting isn’t needed, you can eat and drink normally, but avoid caffeine or large amounts of calcium-rich foods (like dairy) that day.
  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