Intact Parathyroid Hormone (iPTH)
Also known as: iPTH Test, Parathormone, Parathyroid Hormone Intact, Calcium Regulation Hormone
Parameters Measured in the Report
A breakdown of individual biomarkers and biological reference intervals typically found in your report:
| Biomarker | Standard Range | Unit | What It Means |
|---|---|---|---|
Intact PTH (iPTH) (PTH) | 15–65 | pg/mL (ng/L) | Biologically active parathormone regulating calcium homeostasis and bone turnover. |
* Note: Reference ranges may vary slightly between testing instruments and reagent kits. Always refer to the reference interval printed on your specific pathology report.
Clinical Focus
Biologically intact 84-amino acid polypeptide hormone secreted by the four parathyroid glands.
Sample & Specimen
Venous blood (EDTA plasma or Serum immediately chilled on ice)
Fasting Protocol
Overnight fasting of 8 to 10 hours preferred; drawn simultaneously with serum calcium.
Turnaround Time
12–24 hours
What Is This Test?
Why Did Your Doctor Order This Test?
Physicians routinely prescribe the Parathyroid (iPTH) in the following clinical scenarios:
How to Prepare Before Your Test
- Overnight fasting is recommended. Morning blood draw is preferred.
- Must be drawn concurrently with a Serum Calcium and Phosphorus test for accurate clinical interpretation.
Understanding Your Results
What higher or lower readings generally mean in clinical practice:
If Values Are Higher Than Normal
High PTH accompanied by High Calcium confirms Primary Hyperparathyroidism (typically caused by a benign parathyroid adenoma). High PTH accompanied by Low or Normal Calcium indicates Secondary Hyperparathyroidism, classically caused by chronic kidney disease or severe Vitamin D deficiency.
If Values Are Lower Than Normal
Suppressed or low PTH (<15 pg/mL) accompanied by High Calcium indicates non-parathyroid hypercalcemia, most commonly caused by malignancy (bone metastases or PTHrP secretion) or Vitamin D toxicity. Low PTH with Low Calcium confirms Hypoparathyroidism (often following thyroid surgery).
Frequently Asked Questions
Why must PTH always be interpreted alongside calcium?
PTH and calcium work in a reciprocal feedback loop. A PTH level of 50 pg/mL is completely normal when calcium is 9.5 mg/dL, but that exact same PTH level of 50 pg/mL is inappropriately high and abnormal if serum calcium is 11.5 mg/dL.
Related Laboratory Tests
Tests frequently prescribed together or used as follow-up investigations:
Serum Calcium & Phosphorus
Total circulating Calcium (free ionized plus albumin-bound) and Inorganic Phosphorus (Phosphate).
Vitamin D3 (25-Hydroxy Vitamin D)
Total circulating concentration of 25-hydroxyvitamin D (D2 and D3 combined).
Kidney Function Test (KFT / RFT / Renal Panel)
Serum Creatinine, Blood Urea Nitrogen (BUN), eGFR (filtration rate), Uric Acid, and Electrolytes.
Medical & Diagnostic Disclaimer
This guide is published for educational and patient informational purposes only. It is not a substitute for professional medical evaluation, diagnosis, or clinical advice.
A laboratory result that falls slightly outside standard statistical reference intervals does not automatically indicate disease; conversely, a normal result does not guarantee the absence of medical conditions. Only your attending physician can interpret lab findings in the context of your medical history, physical exam, and symptoms.