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Plasma/Serum Parathyroid Hormone (PTH) by Immunoassay

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

This test measures the level of active parathyroid hormone (PTH) in your blood. PTH helps regulate calcium and phosphorus levels in your body.

Quick summary

["PTH helps maintain healthy bone and kidney function by controlling calcium levels."]

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

Key facts at a glance

LOINC
3965-1
Short code
PPA Ur Ql
Synonyms
PPA Ur Ql
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is PTH Used For?

Doctors may order PTH testing to diagnose or monitor conditions affecting calcium metabolism, such as hypoparathyroidism (low PTH), hyperparathyroidism (high PTH), or kidney disease. It can also help assess bone health or evaluate symptoms like muscle weakness, bone pain, or frequent bone fractures.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it is analyzed using an immunoassay method to detect and measure PTH levels.

What Are Common Reasons for Testing?

Common reasons include evaluating symptoms like unexplained low calcium levels, diagnosing conditions like hypoparathyroidism, monitoring treatment for conditions affecting PTH, or checking for metabolic bone diseases.

What Do Results Mean?

Results may indicate whether PTH levels are too high or too low, which can guide treatment decisions. However, interpretation depends on your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

PTH (Active)

Frequently asked questions

Why might my doctor recommend this test if my calcium levels seem normal?
Your doctor may order PTH testing even if calcium levels appear normal to assess PTH function specifically, especially if you have symptoms like muscle spasms, fatigue, or unexplained bone problems.
Could diet or supplements affect PTH test results?
Dietary calcium intake, vitamin D levels, and certain medications (like calcium supplements or anticonvulsants) can influence PTH. Your doctor may advise temporary adjustments if needed.
What if my PTH level is outside the expected range?
If your PTH level is abnormal, your doctor will discuss next steps, which may include additional tests (like calcium or vitamin D levels) or treatments to address the underlying cause.
  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