Parathyroid Hormone (PTH) by Immunoassay (Serum)

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

This test measures your blood levels of parathyroid hormone, a key regulator of calcium and bone metabolism.

Quick summary

["PTH helps balance calcium in your body and supports bone health."]

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

Key facts at a glance

LOINC: 94629-3
Short code: M avium paraTB DNA Ct Spec Qn NAA+probe
Synonyms: M avium paraTB DNA Ct Spec Qn NAA+probe
Category: chemistry
Sample: serum
Container: Red-top tube (SST)
Units: N/A
Fasting: false
Population: adult
Sex: all
Age range: 18–65 years
Method: probe-amp-tar
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

What Is Parathyroid Hormone (PTH)?

PTH is a hormone produced by your parathyroid glands, which are tiny glands located near your thyroid. It plays a critical role in maintaining calcium and phosphorus levels in your blood. When your blood calcium levels drop, PTH signals your body to release calcium from bones and increase its absorption from food. Conversely, it helps remove excess calcium from your blood by promoting its excretion in urine.

Why Might You Need This Test?

Your doctor may order a PTH test if you have symptoms like bone pain, muscle weakness, or abnormal calcium levels. It’s also used to diagnose conditions such as hyperparathyroidism (too much PTH) or hypoparathyroidism (too little PTH), or to monitor treatment for these conditions.

Common Conditions Affecting PTH Levels

High PTH levels (hyperparathyroidism) can lead to weakened bones, kidney stones, or heart issues. Low PTH levels (hypoparathyroidism) may cause muscle spasms, numbness, or irregular heartbeat. Other conditions like kidney disease or vitamin D deficiency can also influence PTH levels.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm or hand to draw a blood sample. The process is quick and usually painless. If you’re on blood thinners, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance of PTH Levels

Short name

PTH (Serum)

Frequently asked questions

How long does it take to get the results of this test?

Results are typically available within 1–3 business days, depending on your lab. Your doctor will discuss the findings with you during your follow-up visit.

Can diet or supplements affect PTH levels?

Yes, certain foods and supplements can influence PTH levels. High calcium intake or vitamin D supplements may lower PTH, while low calcium intake can raise it. Always check with your doctor before making significant dietary changes.

Is this test painful?

Most people experience only mild discomfort or a small pinch during the blood draw. Most people recover quickly, and any bruising or soreness should fade within a day or two.

Sources

1
MedlinePlus — Laboratory TestsSource
2
Lab Tests OnlineSource
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