Parathyroid Hormone-related Peptide
| Parathyroid Hormone-related Peptide | | | |
| Number | | 140194 |
| CPT | | 83519 |
| Synonyms | | PTH-Related Peptide (PTH-rP) |
| Special Instructions | | Contact LabCorp supply department for collection kit and frozen transport tube with cap. |
| Specimen | | Plasma with Trasylol®, frozen |
| Volume | | 1 mL |
| Minimum Volume | | 0.4 mL (Note: This volume does not allow for repeat testing.) |
| Container | | Lavender-top (EDTA) tube, chilled |
Collection | | Collect 6 mL blood into chilled lavender-top (EDTA) tube.
Add 0.25 mL Trasylol® [aprotinin (10,000 KIU/mL)], or
obtain a Trasylol® collection kit (LabCorp ID 33328), which
contains EDTA tubes with Trasylol®. Follow the instructions
with the kit. Mix specimen well, centrifuge, and transfer
the plasma into a LabCorp PP transpak frozen purple tube
with screw cap (LabCorp ID 49482). The specimen should be
frozen immediately and maintained frozen until tested. Send
specimen frozen. To avoid delays in turnaround time when
requesting multiple test on frozen samples, please submit
separate frozen specimen for each test requested. |
| Storage Instructions | | Freeze |
| Causes for Rejection | | Thawed specimen; serum specimen collected without protease inhibitor; recently administered isotopes |
| Reference Interval | | 0.0-1.5 pmol/L |
| Use | | PTH-related peptide (PTHrP) is the principle mediator of humoral hypercalcemia of malignancy. This protein occurs in three isoforms of 139, 141, and 173 amino acids in length. The first 139 N-terminal amino acids of these isoforms are identical. The first fifteen N-terminal amino acids are similar to those of intact PTH, causing PTHrP to bind to PTH receptors and mimic the action of PTH. PTHrP production results in hypercalcemia and hypophosphatemia. PTH-rP has been found to be elevated in 50% to 90% of patients with hypercalcemia of malignancy. |
| Limitations | | Serum PTHrP levels can be transiently elevated during pregnancy, particularly during the third trimester, due to production of PTHrP by the fetoplacental unit.1 This procedure may be considered by Medicare and other carriers as investigational and, therefore, may not be payable as a covered benefit for patients. |
| Methodology | | Immunoradiometric assay (IRMA) |
| Footnotes | | - Hirota Y, Anai T, and Miyakawa I, “Parathyroid Hormone-Related Protein Levels in Maternal and Cord Blood,” Am J Obstet Gynecol, 1997, 177(3):702-6
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| References | | Bilezikian JP, “Measurement of Parathyroid-Related Peptide in the Circulation,” Trends Endo Metab, 1991, 2:1. Endres DB and Rude RK, “Mineral and Bone Metabolism,” Tietz Textbook of Clinical Chemistry, 3rd ed, Burtis CA and Ashwood ER, eds, Philadelphia, PA: WB Saunders Co, 1999, 1395-457. |
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