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Human Parathyroid Hormone (Active), Serum

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

This test measures the active form of parathyroid hormone (PTH), a key hormone that helps regulate calcium and phosphate levels in your blood.

Quick summary

["Active PTH helps balance calcium for strong bones and nerve function."]

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

Key facts at a glance

LOINC
50597-4
Short code
HPA-2 Bld
Synonyms
HPA-2 Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order this test if you have symptoms like bone pain, frequent fractures, or unusual fatigue, or if you have conditions like hypoparathyroidism, hypercalcemia, or kidney disease that affect calcium levels.

What Does a Low or High Level Mean?

Low active PTH levels may suggest hypoparathyroidism (low calcium), while high levels could indicate hyperparathyroidism (excess calcium) or kidney problems.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where it’s analyzed for active PTH using a sensitive immunoassay method.

What Should You Do Before the Test?

No special preparation is needed, but inform your doctor about any medications (like calcium supplements) or recent calcium-rich foods/drinks that might affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Active PTH

Frequently asked questions

What causes abnormal active PTH levels?
Abnormal levels can result from thyroid or parathyroid gland issues, kidney disease, vitamin D deficiency, or certain cancers that produce PTH-related proteins.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time.
Can I eat or drink before this test?
You can eat and drink normally unless your doctor advises otherwise, as active PTH levels don’t require fasting.
  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