Parathyroid hormone-related protein(50-69) and response to pamidronate therapy for tumour-induced hypercalcaemia.
A region-specific radioimmunoassay has been employed to measure levels of immunoreactive parathyroid hormone-related protein(50-69) (iPTHrP(50-69)) in patients with tumour-induced hypercalcaemia (TIH). This assay is based on an antiserum raised against synthetic human PTHrP(50-69). The assay showed no cross-reactivity with human or bovine parathyroid hormone(1-84). The effect of a single dose (60 mg) of pamidronate was studied in 25 consecutive patients with TIH. All were rehydrated prior to treatment. All but 2 patients (8%) became normocalcaemic after treatment; both of these had very high levels of iPTHrP(50-69). Time to achieve normocalcaemia, as an index of relative resistance to pamidronate, correlated positively with pretreatment level of iPTHrP(50-69). Absence of radiological evidence of bone metastases also predicted relative resistance to pamidronate. In this study, iPTHrP(50-69)-induced osteoclastic bone resorption was a more important mechanism in the causation of TIH than PTHrP-induced renal reabsorption of calcium as assessed by the renal thresholds for calcium and phosphate.
Dodwell
D J
DJ
Department of Medical Oncology, Christie Hospital, Manchester, U.K.
Abbas
S K
SK
Morton
A R
AR
Howell
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000556:secondary; D001943:Breast Neoplasms / Q000150:complications; D004164:Diphosphonates / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000097:blood / Q000188:drug therapy* / Q000209:etiology; D008175:Lung Neoplasms / Q000150:complications; D008228:Lymphoma, Non-Hodgkin / Q000150:complications; D008297:Male; D008875:Middle Aged; D000077268:Pamidronate; D010281:Parathyroid Hormone / Q000097:blood*; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins / Q000378:metabolism*
D004164:Diphosphonates; C470121:PTHLH protein, human; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins; D000077268:Pamidronate