Preventing unnecessary parathyroidectomy – the importance of measuring 24 hour urine calcium creatinine ratio and the role of genetic testing in patients with equivocal results.
Vakilgilani T, Tanday R, Falinska A, Ling Y, Todd JF
Imperial College Healthcare NHS Trust.
A 48 years old lady was referred to our Endocrine clinic for investigation of a recurrent hypercalcaemia following three glad parathyroid removal.
She had a past medical history of hypothyroidism, type II DM, hypercholesterolemia and vitamin D deficiency. She was on Metformin, ranitidine, simvastatin, levothyroxine, gliclizide, aspirin and sitagliptin.
She was initially found to be hypercalcaemic incidentally in 2010; however, she was completely asymptomatic. Blood test revealed corrected calcium: 2.86(2.15-2.58), phosphate: 0.89(0.74-1.52), PTH: 3.5 in context of normal vitamin D level of 96 nmol/L post replacement.
Further investigations showed normal PEP, serum ACE and TFTs. She had 24hour urine calcium 7.5 mmol/24 hours (0-7.5); however the urine calcium creatinine ratio was not checked. Localization studies were unhelpful. DEXA scan and USS KUB were normal.
At operation all the glands looked normal. Three-gland parathyroidectomy was performed in 2012 and the histopathology revealed hyperplasia. Her calcium level initially fell to 2.53 mmol/ L post surgery; however it climbed up again to 2.76 mmol/L in 2013 and at this point he was referred to us to investigate possible recurrent hyperparathyroidism.
She remained asymptomatic and she denied any family history of hypercalcaemia. Vitamin D level at this point was low and we decided to repeat her 24 hour urine for calcium/creatinine ratio when Vitamin D replete to re-evaluate the initial diagnosis. As we were highly suspicious of FHH, CASR genetic testing was also sent and results are still pending.
This case highlights the importance of checking urine calcium creatinine ratio and utilizing available genetic tests when we have a borderline result. It can potentially affect patient’s management and prevent an unnecessary surgery. It will be also useful for the family members in case if they develop the same issue to get an appropriate management.