Parathyroid Hormone (PTH), Intact

Additional Information:

UFHPL Epic order code: LAB4438

PTH is an 84-amino-acid peptide hormone which is responsible for the regulation of serum calcium levels within a narrow range. PTH is secreted in response to decrease in serum calcium levels by increasing the renal reabsorption of calcium and lowering reabsorption of phosphorus. The measurement of PTH is a very useful tool in the differential diagnosis and management of hypercalcemia. PTH assays can be of help in the diagnosis of tumors and hyperplasia of the parathyroid gland, as well as in localizing hyperfunctioning parathyroid tissue by assay of samples obtained via venous catheterization. The native or intact (1-84) PTH has a short half-life, measured in minutes, whereas the carboxy and midmolecule fragments, which are biologically inactive, have half-lives 10- to 20-fold higher. The high concentrations of biologically inactive fragments have interfered with use of C-terminal or midmolecule assays for evaluation of parathyroid function in patients with impaired renal function. Intact PTH assays provide a more accurate assessment of parathyroid patients including those with various renal diseases.


  1. Soldin SJ, Brugnara C, Gunter KC, et al. Pediatric Reference Ranges. 2nd ed. Washington, DC: AACC Press;1997:119.


  • Brown RC, Aston JP, St John A, et al. Comparison of poly- and monoclonal antibodies as labels in a two site immunochemiluminometric assay for intact parathyroid hormone. J Immunol Methods. 1988; 109(1):139-144. PubMed 3356909
  • Endres DB, Villaneuva R, Sharp CF Jr, et al. Immunochemiluminometric and immunoradiometric determinations of intact and total immunoreactive parathyrin: Performance in the differential diagnosis of hypercalcemia and hyperparathyroidism. Clin Chem. 1991; 37(2):162-168. PubMed 1993319
  • Kao PC, van Hearden J, Grant CS, et al. Clinical performance of parathyroid hormone immunometric assays. Mayo Clin Proc. 1992; 67:637-645. PubMed 1434896
  • Nussbaum SR, Zahradnik RJ, Lavigne JR, et al. Highly sensitive two site immunoradiometric assay of parathyrin, and Its clinical utility in evaluating patients with hypercalcemia. Clin Chem. 1987; 33(8):1364-1367.PubMed 3608153

CPT Code(s):


Collection Procedure:

Transfer separated plasma into a plastic transport tube, clearly labeled as “EDTA Plasma,” and store the sample at a refrigerated temperature.

Specimen Requirements:

Type: Plasma (preferred)
Container/Tube: Lavender-top tube (EDTA)

Sample Volume: 1.5 mL

Minimum Volume: 0.7 mL (Repeat testing is not possible with this specimen volume.)

Storage: Refrigerate specimens after collection.

Stability (collection to time of analysis/testing):

  • Ambient: 3 days
  • Refrigerated: 3 days
  • Frozen: 14 days
  • Freeze/Thaw cycles: Stable (x3)
Rejection Criteria:

  • Whole blood
  • Plasma other than EDTA
  • Hemolysis
  • Room temperature or refrigerated serum


This test is used to diagnose parathyroid disease and other diseases of calcium homeostasis. It is also used to monitor patients undergoing renal dialysis


Electrochemiluminescence immunoassay (ECLIA)

Reference Values:

Reference Intervals

Intact PTH



15 – 65

8.6 – 10.2


> 65

> 10.2

Primary hyperparathyroidism

> 65

< 10.2

Secondary hyperparathyroidism

< 65

> 10.2

Nonparathyroid hypercalcemia

< 15

< 8.6


15 – 65

< 8.6

Nonparathyroid hypocalcemia