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Parathyroid Hormone (Active), Serum

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

This test measures the active form of parathyroid hormone (PTH), a key regulator of calcium levels in your body.

Quick summary

["Active PTH helps balance calcium and phosphate, crucial for bone health and nerve function."]

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

Key facts at a glance

LOINC
110198-9
Short code
PTH Ab Msmt Ser
Synonyms
PTH Ab Msmt Ser
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 This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like bone pain, frequent fractures, or unexplained kidney stones, or if you have conditions like hypoparathyroidism, hypercalcemia, or kidney disease.

What to Expect Before the Test

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

How the Results Are Used

Results help diagnose or monitor conditions affecting calcium metabolism, such as low or high PTH levels, which can indicate issues like vitamin D deficiency, kidney problems, or thyroid disorders.

Common Conditions Monitored

Active PTH is often checked in patients with suspected hypoparathyroidism (low PTH), hyperparathyroidism (high PTH), or conditions like pseudohypoparathyroidism, where PTH resistance occurs.

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

Short name

Active PTH

Frequently asked questions

What does a high or low result mean?
High levels of active PTH may suggest overactive parathyroid glands, which can lead to excess calcium in the blood, potentially causing kidney stones, weak bones, or heart issues. Low levels may indicate underactive parathyroid glands or other metabolic disorders.
How often should I get this test?
Your doctor will determine the frequency based on your health condition. For example, patients with chronic kidney disease or thyroid disorders may need monitoring more often than others.
Can diet or supplements affect this test?
Yes, calcium-rich foods, vitamin D, and some supplements can influence PTH levels. Avoiding large calcium doses 24 hours before testing helps ensure 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