Case 3

You order thoracic and abdominal radiographs, which reveal mild bronchiolar changes in Harley's lungs and mild lumbar spondylosis.

Fortunately, Harley's owner has also approved submission of a sample for ionized calcium and PTH concentrations today.

A note about using PTH-related protein in the diagnosis of humoral hypercalcemia of malignancy: While this hormone may be elevated in some cases of malignancy, remember not all neoplasms secrete it, so a negative result would not rule out neoplasia. Also remember we can see false elevations in patients with chronic renal failure.

The results:

Ionized calcium = 1.63 nmol/L (reference range = 1.25-1.45 nmol/L)

PTH = 50 pg/ml (reference range = 5-58 pg/ml)

QUESTION 6

What is the appropriate interpretation of these findings?

a) Renal secondary hyperparathyroidism

b) Neoplasia

c) Primary hypoparathyroidism

d) Primary hyperparathyroidism

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