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Parathyroid Hormone (Active), Serum

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

This test measures the active (bioactive) form of parathyroid hormone (PTH) in your blood. It helps assess how well your parathyroid glands are functioning and whether your calcium levels are balanced.

Quick summary

["Active PTH helps regulate calcium and bone health by checking your body’s ability to respond to low calcium levels."]

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

Key facts at a glance

LOINC
58858-2
Short code
PTH-Intact p chal SerPl-mCnc
Synonyms
PTH-Intact p chal 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 kidney stones. It’s also used to monitor conditions like hypoparathyroidism, hyperparathyroidism, or kidney disease that affect calcium metabolism.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your lab requires it. Bring any medications you’re taking to your appointment.

What the Test Involves

A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood is sent to a lab for analysis.

What the Results Mean

Results help doctors diagnose or manage conditions linked to abnormal PTH levels, such as calcium imbalances or metabolic disorders. Your doctor will interpret results in relation to your symptoms and medical history.

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

What causes abnormal active PTH levels?
Abnormal active PTH levels can result from thyroid disorders, kidney problems, vitamin D deficiency, or genetic conditions. Symptoms like muscle weakness, fatigue, or bone pain may also prompt testing.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you once they’re ready.
Can I eat or drink before the test?
Most labs recommend fasting for 8–12 hours before the test unless instructed otherwise. Always follow your doctor’s specific guidelines.
  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