Parathyroid Hormone (Active), Serum
This test measures the active form of parathyroid hormone (PTH), a key regulator of calcium levels in your body.
["Active PTH helps balance calcium and phosphorus, affecting bone health and nerve function."]
Key facts at a glance
- LOINC
- 50532-1
- Short code
- PTH-Intact sp8 SerPl-mCnc
- Synonyms
- PTH-Intact sp8 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 Might Be Ordered
Your doctor may recommend this test if you have symptoms like bone pain, frequent fractures, or unexplained kidney stones. It’s also used to monitor conditions like hyperparathyroidism or hypoparathyroidism, or to check calcium levels in patients with kidney disease or vitamin D deficiency.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. Avoiding certain foods or supplements (like calcium or vitamin D) for 48 hours before testing may help ensure accurate results, but always follow your doctor’s instructions.
What the Results Mean
High active PTH levels may indicate overactive parathyroid glands or conditions affecting calcium metabolism. Low levels could suggest underactive thyroid or other hormonal imbalances. Your doctor will interpret results in relation to your overall health and symptoms.
Common Conditions Monitored
This test is critical for diagnosing or managing hypercalcemia (high calcium), hypocalcemia (low calcium), or parathyroid disorders. It’s also used in patients with chronic kidney disease or metabolic bone diseases.
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.
Active PTH is a more precise marker than total PTH because it reflects the biologically active form of the hormone. Abnormal levels can signal underlying issues like kidney disease, vitamin D deficiency, or primary hyperparathyroidism, which may require medical treatment or lifestyle adjustments.
Short name
Active PTH
Frequently asked questions
What causes abnormal active PTH levels?
How long does it take to get results?
Can diet affect active PTH levels?
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