Skip to content

Parathyroid Hormone (Active), Serum/Plasma

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. It helps assess how well your thyroid glands are functioning to maintain healthy blood calcium.

Quick summary

["Active PTH helps diagnose and monitor conditions affecting calcium balance, including hypoparathyroidism or hyperparathyroidism."]

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

Key facts at a glance

LOINC
86917-2
Short code
PTH-Intact goal mCnc SerPl
Synonyms
PTH-Intact goal mCnc SerPl
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 Matters

Your doctor may order an active PTH test if you have symptoms like muscle weakness, bone pain, or abnormal calcium levels. It’s also used to evaluate conditions such as kidney disease, vitamin D deficiency, or thyroid disorders.

What to Expect Before the Test

No special preparation is usually needed, but avoid eating or drinking anything (except water) for 8–12 hours before your blood draw. Tell your doctor about any medications you’re taking, as they may affect results.

How the Test Works

A small sample of your blood is taken from a vein, typically in your arm. The sample is sent to a lab where it’s analyzed to measure the active PTH level using a sensitive immunoassay method.

Possible Results and Interpretation

Results are compared to reference ranges specific to your age, sex, and overall health. Low active PTH may indicate underactive thyroid glands, while high levels could suggest overactivity or other metabolic issues.

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 low active PTH level mean?
A low active PTH level may signal hypoparathyroidism, where your body doesn’t produce enough PTH to regulate calcium properly. This can lead to symptoms like muscle cramps, numbness, or irregular heart rhythms. Further testing may be needed to confirm the diagnosis and guide treatment.
What does a high active PTH level mean?
High active PTH levels often point to hyperparathyroidism, where your thyroid glands produce too much hormone. This can cause calcium deposits in tissues, kidney stones, or bone weakness. Your doctor may recommend lifestyle changes, medications, or surgery to manage symptoms.
Can diet affect my active PTH test results?
Yes, diet can influence calcium and vitamin D levels, which indirectly affect PTH. Avoiding excessive calcium-rich foods or supplements for a few days before testing may help reduce variability. Always follow your doctor’s instructions for optimal 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