Parathyroid Hormone-Related Peptide
(PTHrP)

Sample type

frozen plasma with aprotinin (EDTA)

Uses

• PTHrP is useful clinically in differentiating primary hyperthyroidism from HHM. Also useful as a marker in the management of patients with tumor associated hypercalcemia.

• The usual pattern of HHM is elevated total and ionized calcium, low PTH in the absence of other causes of hypercalcemia (e.g., excessive vitamin D, sarcoid, TB).

• If the presence of a malignancy is uncertain, or there are several possible causes for hypercalcemia, measurement of PTHrP can be of assistance.

Precautions

Collect into chilled or prefrozen plastic lavender-top (EDTA) tube, noting the time of collection.

After venipuncture, immediately invert tube several times to ensure complete mixture.

Separate plasma from cells by centrifugation. Separate plasma into a plastic vial, and freeze within 15 minutes of collection. To avoid delays in turnaround time when requesting multiple tests on frozen sample, please submit separate frozen specimens for each test requested

Interfering factors

Production of PTHrP by the fetoplacental unit can cause transient increase during pregnancy, especially in the third semester.

Primary hyperparathyroidism occurs in ≤10% of patients with HHM as well as in those receiving thiazides, or with other causes of hypercalcemia.

Pre-analytical errors

1. Non-frozen sample received; non-separated sample received; non-EDTA plasma specimen; gross icterus, and unlabeled specimen

The corrective action

The sample must be rejected and another sample will be requested.

1. put the specimen at room temperature for a long time; this may affect the result.

The corrective action

If you can’t do the test within a short time, you should put it in the refrigerator (at 4C) to prevent contamination of the specimen.

Post-analytical errors

I. reports were sent to the incorrect patient

The corrective action

communication with patient, apologizing for the error, and providing him with the correct report

II. write the wrong name in the report or the wrong results.

The corrective action

If the report is not delivered to the patient and this error is discovered, the correct result or the correct name must be written, but if the report is delivered to the patient, you must communicate with him, apologies to him, and tell him that an error has occurred and replace it with the correct report.

Reference range

PTHrP<2.5pmol/L