Aims: Hypokalemia is a common electrolyte imbalance with signficent effects. The aim of our study is to identify incidence, causes and prognostic implications of postoperative hypokalemia in elderly patients operated for fracture neck of femur.

Methods and material: Retrospective study, of 404 consecutive fracture neck of femur patients who were operated in our hospital between October 2001 and July 2003. Patients identified with postoperative hypo-kalemia the medical notes, fluid charts and anaesthetic notes were analysed for age, preoperative morbidities, medications, mechanism and type of injury, waiting time for operation, pre, peri and postoperative fluid management, type of anaesthesia, operative time, hospital stay and mortality.

Results: Out of the 404 patients, 54(13.3%) were hypokalemic (K< 3.5mmol/l) postoperatively. Of the 54 patients 16 (29.6%)had preoperative hypokalemia.

Among the hypokalemic group the mean preopera-tive potassium was 3.69mmol/l and the mean postoperative potassium was 3.19mmol/l. The t-test showed a statistically significant difference between mean pre and postoperative potassium levels. (P< 0.0001). High association was found with hypokalemia and post-operative dextrose infusion (38%). 50% of patients on diuretics developed hypokalemia post operatively. Interestingly, only 18% of these were hypokalemic pre operatively.

In patients with multiple medical problems, like diabetes, hypertension and CVA, high incidence of hypokalemia was found. (38% had 2 or more medical problems).

No significance in the mortality rate was found in fracture neck of femur patients with and without postoperative hypokalemia (40% vs. 39% at 3yrs).

Conclusion: There is significant risk of hypokalemia following orthopaedic surgery, especially in the elderly. This avoidable condition, which has serious consequences, should be dealt with care in the orthopaedic units. Fluid infusion regimes and should be formulated and medications reviewed to prevent conditions like hypokalemia.