Endocrine Abstracts

We set out to describe a case of persistent PTH elevation post parathyroid carcinoma resection and assess its significance via literature review. A 71 year old lady presented with abdominal pain and weight loss. Blood tests revealed calcium of 3.42 mmol/l and PTH of 47.8 pmol/l. Ultrasound neck and SESTAMIBI scan suggested right lower parathyroid adenoma. She underwent right inferior parathyroidectomy however histology revealed parathyroid carcinoma with incomplete excision necessitating a right hemi-thyroidectomy and neck dissection. Post-operatively, PTH remained elevated between 13.1 and 33 pmol/l. Calcium level has been normal throughout and she remains asymptomatic. Vitamin D ranged between 25 and 62 nmol/l. MRI neck, SESTAMIBI and whole-body PET scans have shown no evidence of residual/recurrent disease and she remains under close follow-up. Literature reviews have previously revealed that persistent PTH rise after removal of parathyroid adenoma without evidence of recurrent disease is a common metabolic phenomenon. We undertook a literature review searching pubmed/medline using keywords ‘PTH elevation’ and ‘parathyroid carcinoma’ in the English Language up until 2018. We identified the most common cause of raised PTH post resection of parathyroid carcinoma is residual/recurrent disease. There were four cases whereby no evidence of residual or recurrent disease was found, 2 of which had a normal calcium level. The need for multiple imaging modalities and invasive investigations in the cases with confirmed recurrence/residual disease shows the diagnostic challenge this scenario presents and the need to keep a high index of suspicion. We hypothesise there may be a similar metabolic phenomenon post parathyroid carcinoma resection resulting in normocalcaemic persistant PTH elevation. However unlike following parathyroid adenoma resection this is a rare entity and rise in PTH post carcinoma resection is much more likely to reflect residual/recurrent disease.