Endocrine Abstracts

A 45-year-old professional jockey presented as an emergency with a 10 day history of polyuria and polydipsia in excess of 10 l daily. 10 days previously he had suffered a head injury complicated by concussion while horse racing in Norway. There was no significant past medical or drug history but he admitted to the use of ‘wasting’ methods prior to a race to maintain his body weight. Examination was unremarkable. Renal function, liver function, thyroid function, serum calcium and glucose were normal. Serum osmolality was 296 mOsm/kg, urine osmolality was 178 mOsm/kg, urine sodium 30 mmol/l. Urine volume was confirmed to be in excess of 10 l in 24 h. Anterior pituitary function testing was normal. CT/MRI imaging of brain was normal. A diagnosis of cranial diabetes insipidus was made and DDAVP was commenced.

Professional horse racing is a demanding sport with high injury rates and strict weight limitations. Jockeys accept bony fractures and soft tissue injuries as occupational hazards. An average National Hunt jockey falls once in every 30 races with a concussion rate of 2%. Horseracing enforces strict weigh in requirements immediately before and after racing. The term ‘wasting’ is often used in horseracing circles to describe acute weight loss methods engaged in by jockeys prior to racing to meet such limits. ‘Wasting’ methods can include fasting, fluid restriction, fluid loss from sauna’s, abuse of diuretics and laxatives, self-induced vomiting, smoking and excessive exercise.

We postulate that ‘wasting’ can lead to dehydration and changes in the volume of the intracranial CSF and blood. If the subarachnoid space is enlarged it is possbile that the brain will travel further reaching a higher velocity before it meets the skull. This could potentially increase the likelihood of traumatic injury to pituitary and hypothalamus and associated endocrinopathy such as diabetes insipidus.