Parathyroid Hormone (PTH), Intact

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Turnaround Time: 1 day
CPT Code:


Test Type: 1.5 mL Plasma (preferred)
Stability Time:



Room temperature

3 days


3 days


14 days

Freeze/thaw cycles

Stable x3

Reference Range:

See table.1

Intact PTH










Primary hyperparathyroidism



Secondary hyperparathyroidism



Nonparathyroid hypercalcemia






Nonparathyroid hypocalcemia


Diagnosis of parathyroid disease and other diseases of calcium homeostasis; monitoring patients undergoing renal dialysis.

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

Collection Details:

Collection Instructions:

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.

Lavender-top (EDTA) tube (preferable).

Transfer separated plasma into a plastic transport tube clearly labeled as "EDTA Plasma" and maintain at refrigerated temperature.

Refrigerate (preferable).