Endocrine Abstracts

Cerebral salt wasting (CSW) occurs as the result of injury to the central nervous system and is most commonly found among those who have experienced a traumatic brain injury (TBI). Although incidence is varied, it has been reported to be as high as 30% within the patient population presenting to hospital with a TBI. CSW causes hyponatremia with concurrent hypovolemia and increased sodium within urine despite normal renal function. Because of its rare nature, CSW is often misdiagnosed as the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Misdiagnosis of CSW occurs at increased rates within healthcare setting wherein the condition is rarely encountered – as with the current case who presented to a district general hospital. This can have a deleterious impact upon patient outcomes, as the conditions require the introduction of treatment regimens that are the opposite of each other. SIADH calls for fluid restriction, while CSW and its accompanying hypovolemia require sodium and fluid repletion. The following case report details an 81-year-old male patient who presented to a district general hospital following a fall that included trauma to the head and subsequent cerebral haematoma. Incorrectly diagnosed with SIADH, his condition continued to decline (including sodium levels as low as 124 mmol/l and a postural hypotension-induced syncopal episode) despite receiving appropriate treatment for his initial diagnosis. Following a consultation with an endocrinologist, his diagnosis was changed from SIADH to CSW and treatment with > 3 l/day with IV normal saline (0.9% solution) was administered. The patient was also advised to eat and drink as normal. After two days on this regimen, his sodium levels increased to 131 mmol/l and an increase in blood pressure alleviated his postural hypotension. After 27 days in the hospital, the patient achieved normal sodium levels and was discharged with advice to monitor his sodium levels via monthly monitoring with his general practitioner. At follow-up, the patient had maintained healthy sodium levels and an MRI of his head revealed resolution of the cerebral haematoma. Despite CSW and SIADH both causing hyponatremia, their etiologies hold important differences and, consequentially, their treatment requirements should be considered mirror images of each other. In order to effectively diagnose and treat patients with either CSW or SIADH, the awareness of both conditions must be increased among healthcare professionals.