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Parathyroid Hormone (PTH) by Immunoassay (Serum)

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

This test measures the level of parathyroid hormone (PTH) in your blood, which helps regulate calcium and phosphate levels in your body.

Quick summary

["PTH helps maintain healthy bone, muscle, and nerve function by controlling calcium balance."]

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

Key facts at a glance

LOINC
40307-1
Short code
GH 3.5h p Arg SerPl-mCnc
Synonyms
GH 3.5h p Arg SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Is This Test Done?

Your doctor may order this test if you have symptoms like bone pain, frequent fractures, muscle weakness, or abnormal calcium levels. It’s also used to diagnose conditions like hypoparathyroidism or hyperparathyroidism, or to monitor treatment for these conditions.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or hand to draw blood. Tell your doctor about any medications you’re taking, especially those that affect calcium or bones.

What the Test Results Mean

Results help determine if your calcium levels are too high or too low, which can indicate an overactive or underactive parathyroid gland. Your doctor will interpret the results in relation to your symptoms and medical history.

Common Conditions Linked to PTH Levels

High PTH levels may suggest hyperparathyroidism, while low levels may indicate hypoparathyroidism. Other conditions, like kidney disease or vitamin D deficiency, can also affect PTH levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

PTH (Serum)

Frequently asked questions

What causes abnormal PTH levels?
Abnormal PTH levels can result from overactive or underactive parathyroid glands, kidney disease, certain cancers, or medications that affect calcium metabolism.
How long does it take to get test results?
Test results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you once results are ready.
Can I eat or drink before this test?
You can eat and drink normally before this test, as no fasting is required. However, always follow your doctor’s specific instructions for your blood draw.
  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