Identifying a rare cancer that causes hypercalcaemia
Kim S, Porter A, Darko D, Boboye I, Palazzo F
A 34 year old gentleman presented to his General Practitioner on multiple occasions describing symptoms of feeling thirsty all the time and having increased frequency of micturition. He had no other lower urinary tract symptoms. Three separate urine samples sent for microscopy, culture and staining showed abundant white cells but no other abnormality. He was referred to the urologists for investigation of sterile pyuria. This consisted of flexible cystoscopy and ultrasound of the renal tract which revealed bilateral nephrocalcinosis. His next follow up occurred after he contacted the department 4 months after his imaging.
This prompted a Urology recall to outpatients where tests showed a corrected calcium of 3.45mmol/L, phosphate of 0.59mmol/L, parathyroid hormone level of 57.8pmol/L and creatinine of 141μmol/L. It was clear from these results that he had increased frequency of micturition due to polyuria secondary to hypercalcaemia. The patient was admitted to a medical ward and was treated with intravenous fluids for rehydration.
Subsequent Investigations showed a urinary calcium over 24 hours of 9.76mmol. A Sesta MIBI scan showed appearances in keeping with a parathyroid adenoma at the lower pole of the left lobe of the thyroid. Ultrasound of the parathyroid confirmed this finding with a 1.8cm lobulated hypoechoic nodule posterior to the left thyroid. Despite optimised fluid management and a calcimimetic, his serum Ca remained persistently elevated with a corrected calcium of 2.94mmol/L. He was discharged with a diagnosis of a parathyroid adenoma and was prescribed cinacalcet 60mg BD, which was later raised to 90mg QDS, with a definitive plan for parathyroidectomy.
On review by an endocrine surgeon, examination revealed a partially fixed firm nodule on the left anterior neck with no regional lymphadenopathy. A parathyroidectomy was performed and histology demonstrated a parathyroid carcinoma. Post-operatively the patientís corrected calcium was 2.16mmol/L and parathyroid hormone 14.9pmol/L.
Parathyroid cancers remain hyper functional unlike other endocrine tumours that become less hormonally active when malignant.  The clinical features of parathyroid carcinoma are caused primarily by the effects of excessive secretion of parathormone (PTH) by the tumour rather than by the infiltration of vital organs by tumour cells. In Europe, the United States, and Japan, parathyroid carcinoma has been estimated to account for .017% to 5.2% of cases of† hyperparathyroidism [1, 2,3,4 ]
For the Endocrinologist Parathyroid carcinoma should be suspected clinically if:
Cincalcet has been reported to reduce serum calcium in patients with inoperable parathyroid cancer  and may be a useful adjunct to Surgery in the future for this gentleman.