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Parathyroid Hormone (Active) - Serum

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

This test measures your active form of parathyroid hormone (PTH), a protein that helps regulate calcium levels in your body. It’s important for bone health, nerve function, and muscle activity.

Quick summary

["Active PTH helps balance calcium and supports vital bodily functions."]

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

Key facts at a glance

LOINC
50530-5
Short code
PTH-Intact sp6 SerPl-mCnc
Synonyms
PTH-Intact sp6 SerPl-mCnc
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 Is Done

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

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. If you’re on blood thinners or have a history of bleeding disorders, let your doctor know before the test.

What the Results Mean

Results help determine if your calcium and bone health are balanced. Abnormal levels may indicate an overactive or underactive thyroid gland, kidney problems, or other metabolic disorders.

Common Conditions Affecting Results

High levels of active PTH might suggest hyperparathyroidism, while low levels could indicate hypoparathyroidism, vitamin D deficiency, or kidney issues. Your doctor will interpret results in the context of your overall health.

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

Frequently asked questions

How is active PTH different from total PTH?
Active PTH measures the biologically active fragment of PTH that directly regulates calcium and phosphate levels in your blood, while total PTH includes both active and inactive fragments. Active PTH is more precise for assessing true hormonal function.
Does fasting affect active PTH levels?
No fasting is required, but your doctor may consider other factors like recent calcium intake or medications that affect calcium metabolism when interpreting results.
Can active PTH be affected by kidney disease?
Yes, kidney disease can alter PTH metabolism, leading to elevated or suppressed active PTH levels. Your doctor will assess kidney function alongside PTH results to provide a full picture.
  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