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Medline ® Abstract for Reference 40

of 'Hypercalcemia of malignancy: Mechanisms'

Ectopic production of parathyroid hormone by small cell lung cancer in a patient with hypercalcemia.
Yoshimoto K, Yamasaki R, Sakai H, Tezuka U, Takahashi M, Iizuka M, Sekiya T, Saito S
J Clin Endocrinol Metab. 1989;68(5):976.
Severe hypercalcemia (serum calcium, 4.37-4.84 nmol/L) was found in a 70-yr-old man who had a small cell carcinoma of the lung with multiple metastases. The plasma immunoreactive PTH concentration was markedly elevated, as measured in three different PTH assays [N-terminal PTH, 4,650 ng/L (normal, 230-630); midregion PTH, 13,850 ng/L (normal, 180-560); C-terminal PTH, 9,900 ng/L (normal, less than 1,300)], but at autopsy the parathyroid glands were histologically normal. The PTH concentration of a liver metastasis was 503.5 ng/g wet wt (normal liver, less than 4.2-5.9), and the PTH in the tumor extract eluted at nearly the same position as synthetic human PTH-(1-84) on gel filtration chromatography. Northern blot analysis revealed PTH mRNA in the tumor as a single band of 0.9 kilobase. These results indicate that the ectopic PTH production by the lung cancer was the cause of hypercalcemia in this patient.
First Department of Internal Medicine, School of Medicine, University of Tokushima, Japan.