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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) in your blood. PTH helps regulate calcium and phosphate levels in your body.

Quick summary

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

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

Key facts at a glance

LOINC
13928-7
Short code
PTH Ab Ser Ql
Synonyms
PTH Ab Ser Ql
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 Might You Need This Test?

Your doctor may order this test if you have symptoms like bone pain, frequent fractures, or unexplained kidney stones. It’s also used to monitor conditions like hypoparathyroidism, hyperparathyroidism, or kidney disease that affect calcium metabolism.

What Does the Test Measure?

The test detects the biologically active form of PTH, which is the part of the hormone that directly influences calcium levels in your blood. This is different from total PTH, which includes inactive fragments.

How Is the Test Done?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where it’s analyzed to measure the active PTH level.

What Are Common Reasons for Testing?

Doctors often check active PTH when evaluating conditions like hypocalcemia (low calcium), hypercalcemia (high calcium), or when managing long-term kidney disease or bone disorders.

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.

◆Associated findings1

Short name

Active PTH (Serum)

Frequently asked questions

What does an abnormal active PTH level mean?
An abnormal result may signal an imbalance in your body’s calcium and bone metabolism. Your doctor will discuss the results with you and may recommend further tests or treatments based on your symptoms and overall health.
How often should I get this test?
The frequency depends on your medical condition and treatment plan. Your doctor will determine how often you need retests, often based on how your symptoms or lab results change over time.
Can lifestyle changes affect active PTH levels?
Yes, diet (especially calcium and vitamin D intake), exercise, and certain medications (like calcium supplements or bisphosphonates) can influence PTH levels. Always follow your doctor’s advice regarding lifestyle changes.
  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