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The Faculty of Medicine, Technion, Haifa, Israel
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The Faculty of Medicine, Technion, Haifa, Israel
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Severe hypocalcaemia in breast cancer with bone metastasis is a rare finding usually associated with an advanced stage of the disease. We report a case of a 45-year-old woman with a history of local ductal carcinoma in situ (DCIS) of the breast, who presented with muscle tremors and general weakness. Hypocalcaemia was evident, with a positive Chvostek sign and a serum calcium level of 5.9 mg/dL (1.47 mmol/L), phosphorus 5.9 mg/dL (normal range: 2.3–4.7 mg/dL) with normal levels of albumin, magnesium and parathyroid hormone. High oral doses of alpha calcitriol and calcium with i.v. infusion of high calcium doses were instituted, altogether sufficient to maintain only mild hypocalcaemia. A whole-body CT revealed bone lesions along the axial skeleton. A biopsy from a bone lesion revealed a metastasis of breast carcinoma. With this pathological finding, leuprolide (GNRH analogue) and chlorambucil (alkylating agent) were initiated, followed by prompt tapering of infused calcium down to full discontinuation. Serum calcium was kept stable close to the low normal range by high doses of oral alpha calcitriol and calcium. This course raises suspicion that breast metastases to the skeleton caused tumour-induced hypocalcaemia by a unique mechanism. We assume that hypocalcaemia in this case was promoted by a combination of hypoparathyroidism and bone metastasis.
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Severe hypocalcaemia can a presenting symptom for breast cancer relapse.
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Sackler School of Medicine, Tel-Aviv University, Tel Aviv, 69978, Israel
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Sackler School of Medicine, Tel-Aviv University, Tel Aviv, 69978, Israel
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Summary
Acromegaly due to ectopic GHRH secretion from a neuroendocrine tumor (NET) is rare and comprises <1% of all acromegaly cases. Herein we present a 57-year-old woman with clinical and biochemical features of acromegaly and a 6 cm pancreatic NET (pNET), secreting GHRH and calcitonin. Following surgical resection of the pancreatic tumor, IGF1, GH and calcitonin normalized, and the clinical features of acromegaly improved. In vitro studies confirmed that the tumor secreted large amounts of both GHRH and calcitonin, and incubation of pNET culture-derived conditioned media stimulated GH release from a cultured human pituitary adenoma. This is a unique case of pNET secreting both GHRH and calcitonin. The ability of the pNET-derived medium to stimulate in vitro GH release from a human pituitary-cell culture, combined with the clinical and hormonal remission following tumor resection, confirmed the ectopic source of acromegaly in this patient.
Learning points
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Signs, symptoms and initial work-up of acromegaly due to ectopic GHRH secretion are similar to pituitary-dependent acromegaly. However, if no identifiable pituitary lesion is found, somatostatin receptor scan and further imaging (CT, MRI) should be performed.
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Detection of GHRH in the blood and in the tumor-derived medium supports the diagnosis of ectopic GHRH secretion.
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Functional bioactivity of pNET-secreted GHRH can be proved in vitro by releasing GH from human pituitary cells.
