Endocrine Abstracts

Introduction: We present a challenging case of central diabetes insipidus secondary to hypothalamic large B cell lymphoma. These are rare tumors accounting for less than 1% of lymphomas. Conventional treatment involves the MATRIX regime (methotrexate, rituximab, thiotepa, cytarabine) chemotherapy, coupled with intensive intravenous fluid therapy to avoid methotrexate toxicity. The main challenges in the management of this case were maintaining fluid and electrolyte balance in a patient with nearly adipsic DI with ongoing chemotherapy.

Case history: 49 year old female was admitted under hematology with diagnosis of hypothalamic lymphoma associated with panypopituitarism and DI. Matrix chemotherapy involves intensive fluid therapy to induce diuresis and avoid methotrexate toxicity. Therefore desmopressin dose needed to be reduced or withheld to avoid subsequent fluid overload. Patient received 4 cycles of chemotherapy. During each cycle, patient received fluids at the rate of 250 ml/h for a period of 5 days. Ensuring normal sodium levels during these periods were extremely challenging. Alterations including 50 % reduction of the desmopressin dose while on fluids, brief omission of desmopression, reduction of fluid infusion rate as well as alternate route of desmopressin administration were tried. Patient being adipsic followed by intercurrent diarrhoea added to the challenges. Despite intense monitoring, there were episodes of extremes of both hyper and hyponatremia (121–170 mmol/l) as well as significant fluid overload.

Conclusion: This case highlights importance of multidisciplinary management of patients on MATRIX chemotherapy with underlying pituitary dysfunction especially diabetes insipidus. Prompt speciality in reach with frequent monitoring of electrolytes and osmolalities, strict documentation of fluid balance chart and frequent adjustment of desmopressin doses with regular review is pivotal in management of such complex cases.