PTH-Related Protein - UI Health Care

Commercial Mailout Laboratory
6240-8 RCP
356-8593

Specimen(s):

Plasma

Specimen Instructions:

Collect sample in pre-chilled 3 mL lavender EDTA tube.

Collection Medium:

Lavender top tube 3 mL (EDTA)

Minimum:

Preferred Minimum: 0.7 mL
Absolute Minimum: 0.25 mL

Turn Around Time:

2 days upon receipt at reference laboratory

Reference Range:

<2.0 pmol/L

Interpretive Data:

Depending on the patient population, up to 80% of patients with malignant tumors and hypercalcemia will be suffering from humoral hypercalcemia of malignancy (HHM). Of these, 50% to 70% might have an elevated parathyroid hormone-related peptide (PTHrP) level. These patients will also usually show typical biochemical changes of excess parathyroid hormone (PTH)-receptor activation, namely, besides the hypercalcemia, the might have hypophosphatemia, hypercalcuria, hyperphosphaturia and elevated serum alkaline phosphatase. Their PTH levels will typically be less than 30 pg/mL or undetectable.

In patients with biochemical findings that suggest but do not prove primary hyperparathyroidism (eg, hypercalcemia, but normal or near normal serum phosphate and a PTH level that is within the population reference range, but above 30 pg/mL), HMM should be considered as a diagnostic possibility, particularly if the patient is elderly, has a history of malignancy or risk factors for malignancy. An elevated PTHrP level in such a patient is highly suggestive of HHM as the cause for the hypercalcemia.

Methodology:

Immunochemiluminometric Assay (ICMA)

CPT Code:

82397