Skip to content

Parathyroid Hormone (PTH) by Immunoassay

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

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

Quick summary

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

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

Key facts at a glance

LOINC
81550-6
Short code
SPECT+CT Parathyroid gland W RNC IV
Synonyms
SPECT+CT Parathyroid gland W RNC IV
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
nm-spect-ct
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 a PTH test to check for conditions affecting calcium metabolism, such as hypoparathyroidism (low PTH) or hyperparathyroidism (high PTH). It can also help diagnose or monitor kidney disease, bone disorders, or vitamin D deficiency.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm or hand to draw blood. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

PTH levels can vary based on factors like diet, medications, and underlying health conditions. Your doctor will interpret the results in relation to your overall health and symptoms.

Common Conditions Affecting PTH Levels

High PTH levels may suggest hyperparathyroidism, while low levels could indicate hypoparathyroidism. Other conditions like kidney disease or vitamin D deficiency may also influence PTH.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

PTH plays a critical role in regulating calcium and phosphate, which are essential for bone health, nerve function, and muscle activity. Abnormal levels can lead to symptoms like muscle weakness, bone pain, or kidney stones.

Short name

PTH

Frequently asked questions

What causes abnormal PTH levels?
Abnormal PTH levels can result from thyroid disorders, kidney problems, vitamin D deficiency, or certain medications. Lifestyle factors, such as diet or stress, may also play a role.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition, symptoms, and medical history. Regular monitoring may be needed if you have chronic conditions like kidney disease or hyperparathyroidism.
Can diet affect PTH test results?
Yes, certain foods and supplements, like calcium or vitamin D, can influence PTH levels. Your doctor may recommend dietary adjustments or timing your test around meals for more 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 16, 2026. · Read our editorial policy