Parathyroid Hormone (PTH) Plus Calcium

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Turnaround Time: 1 day
CPT Code:

82310, 83970

Test Type: 1.5 mL plasma and 1 mL serum
Stability Time:

Temperature

Period

Room temperature

3 days

Refrigerated

3 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Overview:

Differential diagnosis of hypercalcemia. PTH is an 84-amino acid peptide hormone that 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 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.

Brown RC, Aston JP, St John A, Woodhead JS. Comparison of poly- and monoclonal antibodies as labels in a two-site immunochemiluminometric assay for intact parathyroid hormone. J Immunol Methods. 1988 Apr 22; 109(1):139-144. PubMed 3356909

Endress DB, Villanueva R, Sharp CF Jr, Singer FR. Immunochemiluminometric and immunoradiometric determinations of intact and total immunoreactive parathyrin: Performance in the differential diagnosis of hypercalcemia and hyperparathyroidism. Clin Chem. 1991 Feb; 37(2):162-168. PubMed 1993319

Kao PC, van Hearden J, Grant CS, Klee GG, Khosia S. Clinical performance of parathyroid hormone immunometric assays. Mayo Clin Proc. 1992 Jul; 67(7):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 Aug; 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 and red-top tube or gel-barrier tube

Transfer separated plasma to a plastic transport tube clearly labeled as EDTA plasma and maintain refrigerated temperature. If red-top tube is used, transfer serum to a plastic transport tube clearly labeled as serum.

Refrigerate.