Parathyroid hormone (PTH) - serum

Last updated: Sunday, 21, March, 2004

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Item Process
Specimen

10 mL blood in plain tube. Specimen transported rapidly to laboratory on melting ice.

Method

Immunoassay.

Reference Interval

1.0-7.0 pmol/L (method dependent).

Application

Investigation of unexplained hypercalcaemia and hypocalcaemia.

Monitoring management of osteodystrophy in chronic renal failure.

Interpretation

The interpretation of PTH levels is dependent on the patient’s corrected calcium, or ionised calcium, at the time the blood specimen was taken.

In hyperparathyroidism the PTH level is increased or high normal in the presence of hypercalcaemia.

In most cases of hypercalcaemia associated with malignancy PTH level will be suppressed, often with an elevated PTHrP.

Hypoparathyroidism is associated with a low PTH.

Pseudohypoparathyroidism and other causes of hypocalcaemia are associated with a high PTH.

Effective management of osteodystrophy in chronic renal failure is associated with relatively little or no elevation of PTH.

See also Parathyroid hormone related protein.

Reference

St John A. Clin Biochem Revs 1995; 16: 27-36.