Parathyroid Hormone (PTH), Intact

CPT: 83970
Updated on 7/18/2017
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Test Details

Synonyms

  • PTH Whole Molecule

Use

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

Methodology

Electrochemiluminescence immunoassay (ECLIA)

Reference Interval

See table.1

Intact PTH

(pg/mL)

Calcium

(mg/dL)

Interpretation

15−65

8.6−10.2

Normal

>65

>10.2

Primary hyperparathyroidism

>65

<10.2

Secondary hyperparathyroidism

<65

>10.2

Nonparathyroid hypercalcemia

<15

<8.6

Hypoparathyroidism

15−65

<8.6

Nonparathyroid hypocalcemia

Additional Information

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.

Specimen Requirements

Specimen

Plasma (preferred)

Volume

1.5 mL

Minimum Volume

0.7 mL (Note: This volume does not allow for repeat testing.)

Container

Lavender-top (EDTA) tube (preferable)

Collection

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

Storage Instructions

Refrigerate (preferable)

Stability Requirements

Temperature

Period

Room temperature

3 days

Refrigerated

3 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Whole blood; plasma other than EDTA; hemolysis; room temperature or refrigerated serum

Clinical Information

Special 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.

Footnotes

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

References

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. 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. 1993319
Kao PC, van Hearden J, Grant CS, et al. Clinical performance of parathyroid hormone immunometric assays. Mayo Clin Proc. 1992; 67:637-645. 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):1364-1367.3608153

LOINC® Map

Order Code Order Code Name Result Code Result Code Name UofM Result LOINC
015610 PTH, Intact 015610 PTH, Intact pg/mL 2731-8

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