Endocrine Abstracts

This is a case of forty six year old lady who is known to have resected stage 3 malignant melanoma diagnosed in 2008. She has recently she was started on Ipilimumab, an anti cytotoxic T cell antigen 4(CTLA-4), a monoclonal antibody as part of clinical trial. After two cycles she developed headaches and an MRI scan showed bulky piruitary with an enhacement in keeping with pituitary hypophysisits. She received Dexamethasone 8 mg twice daily with good symptomatic effect. The headache recurred when Dexamethasone was tapered down to 4 mg twice daily after two weeks of treatment. One week later she was admitted to hospital with confusion, sensory dysfunction and acute hyponatraemia. Her routine electrolytes check showed Na 108 mEq/L, K 3.3 mEqu/L with normal urea and creatinine. Further checks were consistent with SIADH with serum osmolality 224 mOsmol/kg, urine osmolality 694 mOsmol/kg and urine Na of 76 mmol/L. TSH, FT3 and gonadotrophins were law. A repeat MRI showed worsening of pituitary hypophysitis. She needed fluid restriction and hypertonic saline infusion to stabilize the sodium. She received high dose methylprednislone followed by Prenislone primarily for hypophysitis but also for sensory gangliopathy. Later Tacrolimus was introduced for further immune suppression. Her pituitary hormone profile normalized. A repeat MRI scan showed the pituitary has regressed to normal size. This case highlights the role of new immune modulator therapies in pituitary pathophysiology. It opens the debate about the need for sensible endocrine monitoring on start of these therapies. This lady had acute SIADH secondary to hypophysitis. The association between Ipilimumab and hypophysitis is well described. This is attributed to an autoimmune process based on the documented relationship of the drug to other autoimmune phenomena and significant rapid improvement with discontinuation of the drug and addition of steroids.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.