Tumour Induced Osteomalacia: Rapid Clinical and Biochemical Control Using Octreotide

Abstract

Aims: To assess the effects of short acting octreotide on the Fibroblast Growth Factor-23 levels and the clinical outcome in a bedridden patient with Tumour Induced Osteomalacia. Presentation of the Case: A 40-year old female, presented with a 16-year history of progressive weakness and bone pains. Severe hypophosphatemia had been documented throughout and she had been treated intermittently with oral phosphate and various preparation of vitamin D.  Hypercalcaemia due to parathyroid hyperplasia was diagnosed 4 years previously. In the last 2 years she had undergone bilateral hip prostheses and removal of 2 hyperplastic parathyroid glands. When seen by us she was bedbound with severe restriction of all joint movements, there was a palpable left buttock mass 4x4 cm. Tumour induced osteomalacia was suspected and confirmed by finding grossly elevated levels of Fibroblast growth factor (FGF-23) 3400 Ru/ml (44-140).The serum calcium 2.5 mmol/L (n 2.1-2.5), phosphate 0.3 mmol/L  (n 0.8-1.45).Alkaline phosphatase (ALP) 400 U/L ( n 35-104), Parathyroid hormone (PTH) 27 pmol/L (n 1.6-9.3) , and creatinine 70 umol/L (n 45-84). Octreotide scanning revealed focal uptake in the buttock corresponding to the MRI findings. Treatment with octreotide 100 mcg 8 hourly was given for 10 days before surgery. By day 3 the FGF-23 had fallen to 400 and on the day of surgery was 210 Ru/ml. A benign mesenchymal tumour was completely resected and 8 weeks following surgery the FGF-23 was normal, serum calcium 2.7 mmol/L, serum phosphorus 0.63 mmol/L, ALP 690 U/L, PTH 22 pmol/L . The patient was then able to walk in a Zimmer frame after 2 months. Since then she recovered completely, she is able to walk without assistance for the last 2 years. Conclusion: This case provides an example of successful use of short acting octreotide in controlling the disease and demonstrated a rapid normalisation of elevated FGF-23 levels achieved during treatment with octreotide. It describes a rare association between tumour induced osteomalacia (TIO) and parathyroid hyperplasia, the value of octreotide scanning in tumour localisation and the potential for using LA octreotide therapy in patients with responsive tumours that cannot be localised or removed for any reason.