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Parathyroid Hormone (PTH) by Immunoassay (Serum)

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

This test measures the level of parathyroid hormone (PTH) in your blood. PTH is a hormone produced by your parathyroid glands that helps regulate calcium and phosphorus levels in your body.

Quick summary

["PTH helps maintain healthy bone and muscle function by controlling calcium balance."]

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

Key facts at a glance

LOINC
2732-6
Short code
PTH-M SerPl-mCnc
Synonyms
PTH-M SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85610
SNOMED
396252006
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 affecting calcium balance, such as hypoparathyroidism (low PTH), hyperparathyroidism (high PTH), or kidney disease. It may also be used to check for vitamin D deficiency or to evaluate symptoms like muscle weakness, bone pain, or frequent bone fractures.

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 your provider recommends it, but this is not always required. Bring any medications you’re taking to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The blood sample is then sent to a lab for analysis using an immunoassay method to measure PTH levels accurately.

What Are Possible Results?

Results will be reported as a numerical value representing PTH concentration in your serum. Your provider will interpret the results in relation to your symptoms, medical history, and other test results.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

PTH (Serum)

Frequently asked questions

What does an abnormal PTH result mean?
An abnormal PTH result may signal an underlying condition like hypoparathyroidism (too little PTH) or hyperparathyroidism (too much PTH). Your provider will review your results alongside other factors, such as symptoms and lab tests, to determine the cause and next steps.
How often should I get this test?
The frequency depends on your health condition. If you have a known disorder like hyperparathyroidism, your provider may recommend regular monitoring. Otherwise, this test is often done as needed for diagnosis or symptom evaluation.
Can I eat or drink before this test?
Some providers may recommend fasting for 8–12 hours before the test, but this isn’t always required. Always follow your provider’s instructions or ask before your appointment.
  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