PTHrP is of most use in hypercalcaemic patients in whom the PTH is suppressed and malignancy is suspected.
PTHrP is found at levels above the reference range in patients with hypercalcaemia of malignancy with varying frequency according to tumour type. It is most frequently elevated in hypercalcaemia in patients with solid tumours and is above the reference range in 85% of such patients with breast tumours, 70% of those with tumours of lung and renal tract origin and 27% of those with gastrointestinal tract tumours.
< 1.8 pmol/L
Elevated PTHrP levels in hypercalcaemic patients with suppressed PTH levels are highly suggestive of malignancy and are associated with a very poor prognosis for long – term survival.
Plasma – EDTA
A single elevated result may be diagnostic for a malignancy and repeat might not be necessary. PTHrP can be used in follow up of patients treated for a malignancy.