Endocrine Abstracts

60 year old gentleman referred to endocrine clinic from Rheumatology for raised PTH 23.5 pmol/l, in the context of normal calcium 2.2 mmol/l, low vitamin D 27.3 nmol/l, raised ALP 273 U/l, low phosphate 0.57 mmol/l and normal renal function. Past medical history of hypertension, Barrett’s oesophagus, cluster headaches and previous left femur fracture secondary to motor cross accident. The ALP isoenzyme for bone was raised. He was complaining of backache which he had for several months which was not precipitated by any injury. Rheumatology had ruled out Paget’s disease with a bone scan which showed increased uptake in the ribs and distal third of the left femur. He was started on vitamin D 50,000units once a week, as low vitamin D was presumed to be the cause of the raised PTH. His PSA and myeloma screen were negative. He felt his strength was reducing and though his vitamin D levels came up, his ALP remained elevated and so did his PTH. He went on to have CT chest/abdo/pelvis which showed diffusely sclerotic bones. PET Scan showed deformity and hyperostosis in the distal 2/3^rd of the left femoral diaphysis, thought to be due to the previous trauma. His PTH remained up despite normal calcium, vitamin D and renal function. His Sestamibi scan revealed a possible right lower parathyroid adenoma but also reported diffuse bony sclerosis suggestive of renal osteodystrophy but his renal function was still normal. His phosphate had dropped to 0.36 mmol/l and he was started on phosphate replacement. The abnormal bone imaging suggested that this was not PTH driven and he was referred to the metabolic bone department. His Procollagen-1-N-Peptide was raised at 907 ug/l and his FGF 23 levels were high at 175 iu/ml (Normal 0 – 100 iu/ml), suggesting the diagnosis of Oncogenic/tumour induced osteomalacia – which is a mesenchymal tumour secreting FGF23. He had a Ga-68 DOTATATE PET/CT scan which showed a possible lesion in the right femur. He is currently awaiting ablation of this. He currently takes 4 sando phosphate tablets a day and 1.5 mcg alpha calcidol. His phosphate is now 0.86 mmol/l. His PTH is 40.7 pmol/l and ALP is 327 U/l.