Endocrine Abstracts

Introduction: Hyponatraemia is a common biochemical abnormality in hospital patients, a robust management plan and correct diagnosis is important in the medical care of these patients. However these are frequently lacking.

Methods: We audited the management and outcomes of hyponatraemia in a large district general hospital. In-patients for a period of 3 months starting from January 2004 with hyponatraemia (Sodium less than reference rang 132-146 mmol per litre) were identified retrospectively from the laboratory database. A team including an endocrinologist, a chemical pathologist and a clinical epidemiologist reviewed the notes and data. All cases were discussed to reach a consensus on the diagnosis.

Results: 91 cases were identified, medical records of 70 patients were reviewed, mean age 74.3+13.4, 15 (21%) were younger than 65 years while 55 (79%) patients were 65 or older. 35.7% were male and 64.3% female. All patients had Glucose, creatinine, urea and electrolytes. Other investigations done were TFT (44.3%), Urine osmolality (22.8%), plasma osmolality (22.8%), urine sodium (18.6%) and short sysnacthin (11.4%). In 46 patients (65.7%) there was no clear diagnosis made on the ward. 21 patients (30%) died in hospital, another 11 patients (16%) died with in 6 months after discharge. Only 38 (54%) patient were still alive 6 months after discharge. Six month mortality was higher in patient aged 75 or more (55%) and in patients with initial sodium level <115 mol/L (53.8%). Hepatic disease was the commonest (53%) cause in patients <65 years and iatrogenic causes (33%) was most commonly seen in patients aged >65 year, with thiazide diuretics the commonest drug implicated.

Conclusion: Hyponatraemia is a serious biochemical abnormality and it is associated with high morbidity and mortality, especially in older people and in patients with very low initial sodium level. However, it is generally under-investigated, arbitrarily managed and a correct diagnosis is commonly not made.