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Serum Calcium (Mass Concentration)

Published: August 9, 2026Updated: August 15, 2026

This test measures the amount of calcium in your blood serum, an important mineral that helps maintain healthy bones, muscles, and nerves.

Quick summary

["Your blood calcium levels help regulate muscle function, nerve signals, and bone health."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
50473-8
Short code
CALC5
Synonyms
Calcit sp5 SerPl-mCnc
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube for serum; lavender-top (EDTA) or green-top (heparin) tube for plasma
Units
N/A
Ref low
0
Ref high
10
Critical range
— – 1000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Chemiluminescent Immunoassay (CLIA) or Electrochemiluminescence Immunoassay (ECLIA)
CPT
82308
SNOMED
39579002
Specimen volume
1-2 mL of serum or plasma
Stability
Room temperature: 8 hours; Refrigerated (2-8°C): 24 hours; Frozen (-20°C or lower): up to 6 months. Avoid repeated freeze-thaw cycles.
Hemolysis max
100
Lipemia max
500
Icterus max
25
TAT
24–72 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, fatigue, or abnormal heart rhythms. It’s also used to monitor calcium balance in people with kidney disease, thyroid disorders, or certain medications.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if your doctor specifies it. Bring any medications you’re currently taking to your appointment.

How the Test Is Performed

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a brief sting, but the procedure usually takes less than five minutes. The blood sample is then sent to a lab for analysis.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL). While reference ranges vary slightly by lab, low levels may indicate conditions like hypoparathyroidism or kidney problems, while high levels could suggest hypercalcemia or overuse of certain supplements.

Reference range

Reference ranges vary by laboratory and assay methodology. Generally, basal calcitonin levels in healthy adults are <10 pg/mL (ng/L). Males typically have slightly higher values than females. Pentagastrin-stimulated calcitonin values are interpreted relative to baseline and clinical context.N/A

Specimen: serum

No special patient preparation is generally required for basal calcitonin measurement. For stimulation testing, specific protocols apply. Patient should be informed that some medications (e.g., proton pump inhibitors, beta-blockers, glucocorticoids) may affect calcitonin levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal calcium levels can affect many body systems. Low calcium may lead to nerve irritation, muscle spasms, or weakened bones, while high calcium can cause kidney stones, confusion, or irregular heartbeats. Regular monitoring is important for people with chronic conditions like osteoporosis, kidney disease, or thyroid disorders.

Short name

Serum Calcium

Frequently asked questions

How often should I get this test?
Your doctor will determine how often you need this test based on your health status, symptoms, and any ongoing conditions. Follow-up tests may be scheduled every few months or as needed for ongoing management.
What causes calcium levels to change?
Calcium levels can be influenced by diet (e.g., excess vitamin D, calcium-rich foods), medications (e.g., thiazide diuretics, bisphosphonates), kidney function, and hormonal imbalances (e.g., thyroid or parathyroid issues). Lifestyle factors like physical activity and sun exposure also play a role.
Can I adjust my diet before the test?
Yes, if your doctor instructed fasting, avoid calcium-rich foods (e.g., dairy, leafy greens) and supplements for the specified period. If no fasting is required, there are no strict dietary restrictions, but consistency is key for 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 15, 2026. · Read our editorial policy