Endocrine Abstracts

A 45 year old male was referred in November 2001 to the endocrine clinic with the complaints of sudden onset marked thirst, polyuria with nocturia (six times) for two months. His past medical history includes a diagnosis of solitary sacral plasmacytoma diagnosed in 1998, based on bone marrow aspirate and trephine in the presence of the paraproteinaemia. He was successfully treated with radiotherapy. There has been no history of head injury and has not been on regular medication. System examination was unremarkable.

Investigations: Sodium 142 millimols per litre, pottassium 4.5 millimols per litre, creatinine 123 millimols per litre. calcium 2.53 millimols per litre. Phosphate 0.81 millimols per litre . Liver and thyroid function test were normal. Fasting glucose 5.5 millimols per litre . LH 2.7 IU/L, FSH 4.1 IU/L. Prolactin 189milli Units perlitre. Testosterone 20 nanomols per litre. Urine osmolality143 milliosmolals per Kilogram. Serum osmolality 305 milliosmolals per Kilogram . Modified water deprivation test: There was no increase in urine osmolality with water deprivation. Injection of desmopressin 2micrograms intramuscular increased urine osmolality to 686 milliosmolals per Kilogram confirming cranial diabetes insipidus. MRI head showed no abnormality. His diabetes insipidus has been well controlled with DDAVP. Following recurrent severe sacral pain he had repeat MRI in September 2003 which demonstrated abnormal enhancement and cystic changes in his sacrum. Further biopsy revealed Langherhans Cell Histiocytosis (LCH). LCH is a rare disorder, mainly affecting children, with clinical manifestations that can vary widely. In LCH, granulomatous deposits occur at multiple sites within the body, but which often involves the hypothalamo-pituitary axis. Diabetes insipidus is a well recognised complication and may predate the diagnosis of LCH as was seen in this patient.