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Parathyroid Hormone (PTH) by Immunoassay (Serum/Plasma)

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

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

Quick summary

["PTH helps balance calcium, which is important for bone health and nerve function."]

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

Key facts at a glance

LOINC
29390-2
Short code
PTH-M SerPl-sCnc
Synonyms
PTH-M SerPl-sCnc
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 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, vitamin D deficiency, or other disorders that influence calcium levels.

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 doctor specifies it. Bring any medications you’re taking to your appointment.

How the Test Is Done

A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch, but it should only take a few minutes. The blood sample is then sent to a lab for testing.

What the Results Mean

Results help determine if your PTH levels are too high or too low, which can indicate underlying health issues. Your doctor will interpret the results in relation to your overall health and symptoms.

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.

Clinical Significance: PTH plays a critical role in maintaining calcium balance. Abnormal levels may signal conditions like kidney disease, bone disorders, or hormonal imbalances that require further medical evaluation.

Short name

PTH Level

Frequently asked questions

What causes abnormal PTH levels?
Abnormal PTH levels can result from thyroid disorders, kidney problems, vitamin D deficiency, or certain medications. Symptoms like muscle weakness, bone pain, or frequent fractures may also prompt testing.
How often should I get this test?
Your doctor will decide how often you need this test based on your health condition, symptoms, and treatment plan. Regular follow-ups may be recommended if you have chronic conditions like kidney disease or osteoporosis.
Can I eat or drink before this test?
If your doctor instructed fasting, avoid food and liquids (except water) for 8–12 hours before the test. Otherwise, you can eat and drink normally unless otherwise directed.
  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