Endocrine Abstracts

Case history: Mrs SC, a 56 year old female was referred to the endocrine registrar with hypocalcaemia (corrected calcium 1.93 mmol/l). She was day 3 post-hemihepatectomy for liver metastases from a primary pancreatic tail neuroendocrine tumour (NET). She had paraesthesia and numbness of her fingers and toes but no spasms. Chvostek’s sign was negative and there were no ECG changes. Past medical history includes severe hypercalcaemia in September 2016 which was found when she presented acutely with abdominal pain. CT abdomen done as a part of the work-up showed a 4.5 cm lesion in the tail of the pancreas and 3× liver metastases, which was subsequently confirmed to be a primary pancreatic NET on SRS octreotide scan and biopsy. She had an open distal spleno-pancreatectomy in 2017 for resection of the primary tumour. Aside from this she had previous breast cancer (in remission) and oesophagitis. Drug history: Octreotide 200 μg TDS S/C, Cinacalcet 30 mg BD, Alendronic acid 70 mg weekly and Colecalciferol 800 IU OD.

Investigations: At diagnosis (09/2016)

Corrected calcium: 4.01 mmol/l (NR 2.1–2.58)

Phosphate: 0.63 mmol/l (NR 0.8–1.4)

PTH: <0.6 pmol/l (NR 1.1–4.2)

PTHrP: 3.2 pmol/l (NR <1.9)

25-hydroxy vitamin D: 24 nmol/l

eGFR: >60 ml/min per 1.73 m²

Pre-operative (29/12/2017)

Corrected calcium: 2.50 mmol/l

PTH: 0.8 pmol/l

25-hydroxy vitamin D: 27 nmol/l

Day 3 post-operative (5/1/2018)

Corrected calcium: 1.94 mmol/l

Phosphate: 1.46 mmol/l

Magnesium: 0.80 mmol/l (NR 0.7–1.0)

eGFR: >60 ml/min per 1.73 m²

Treatment: The sudden post-operative hypocalcaemia was due to loss of PTHrP secretion after removal of the liver metastases. This confirmed the suspicion that her initial hypercalcaemia was due to PTHrP secretion from a NET, which has been described in case reports. This paraneoplastic syndrome tends to occur with metastatic pancreatic NETs and is often responsive to somatostatin analogue therapy or peptide receptor radiotherapy causing hypocalcaemia. In the acute setting, she was given IV calcium gluconate until her calcium increased to >2.1 mmol/l. The Cinacalcet and Alendronic acid was stopped and she was started on Adcal D3 2 tablets TDS. Her calcium on discharge was 2.19 mmol/l.

Conclusions and points for discussion: This is an unusual case of a PTHrP secreting metastatic pancreatic NET causing hypercalcaemia initially and then hypocalcaemia after surgical resection. It is important to monitor calcium levels closely in such patients in the post-operative period.