Parathyroid Hormone (Active, Mid-Molecular Weight)
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 and whether your calcium balance is being managed properly.
["Active PTH levels help diagnose and monitor conditions affecting calcium metabolism."]
Key facts at a glance
- LOINC
- 24347-7
- Short code
- PTH Mid Mol + Ca Pnl SerPl
- Synonyms
- PTH Mid Mol + Ca Pnl SerPl
- Category
- electrolyte
- 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
PTH plays a critical role in maintaining calcium and phosphorus levels in your blood. When your body needs more calcium, PTH signals bones to release it and kidneys to retain calcium. Low or high PTH levels can indicate underlying health issues, such as hypoparathyroidism or hyperparathyroidism.
When It’s Ordered
Your healthcare provider may recommend this test if you have symptoms like muscle weakness, bone pain, or frequent fractures. It’s also used in patients with kidney disease, vitamin D deficiency, or unexplained calcium imbalances.
Sample Collection and Preparation
A blood sample is taken from a vein, usually in your arm. The sample is processed to separate serum or plasma for testing. This test is typically done after fasting, but your provider will confirm timing with you.
Test Results and Interpretation
Results are compared to standard ranges, though individual results can vary based on age, sex, and health status. Your provider will discuss the meaning of your specific results in the context of your overall health.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
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
PTH (active, mid-molecule)
Frequently asked questions
What Does It Measure?
How Might It Be Used?
What Are Common Causes of Abnormal Results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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