Postoperative Prevalence and Risk Factors for Serum Hypokalemia in Patients with Primary Total Joint Arthroplasty.

OBJECTIVE

Regular monitoring of serum potassium after a total joint arthroplasty (TJA) is a form of routine examination that can help detect abnormal serum potassium levels and reduce the incidences of adverse events that may occur on account of postoperative hypokalemia. Previous studies rarely discussed hypokalemia after joint replacement. In the present study, our primary goal was to investigate the incidence and possible risk factors of hypokalemia after a total hip and knee replacement procedure was performed.

METHODS

This study included patients who underwent a unilateral total knee or hip arthroplasty in our department between April 2017 and March 2018. Serum potassium levels pre and post operation were collected and retrospectively analyzed. The differences in age, gender, body mass index (BMI), history of diseases, red blood cell (RBC), hemoglobin, hematocrit, glomerular filtration rate, ejection fraction, blood glucose, urine creatinine, urea nitrogen, intraoperative blood loss, operation time, drainage, preoperative potassium, surgery type, were compared between those patients diagnosed with hypokalemia and their non-hypokalemia at different times post surgery. Thereafter, the risk factors of postoperative hypokalemia patients were analyzed using statistical procedure multiple logistic regression model.

RESULTS

The risk of hypokalemia after TJA was 53.1%, while, that on the first, third, and fifth day after operation was 12.5%, 40.7%, and 9.6% respectively. The serum potassium level on the first, third, and fifth postoperative days was 3.84 ± 0.32, 3.59 ± 0.34, and 3.80 ± 0.32 mmol/l, respectively. However, the level on the third day appeared to be the lowest (p = 0.015) of them all. The independent risk factors for hypokalemia after a total hip and knee replacement were the level of preoperative serum potassium concentration (p = 0.011), preoperative red blood cells counts (p = 0.027), and history of diabetes (p = 0.007).

CONCLUSION

Regular monitoring of serum potassium concentration should be performed post TJA. We need to pay more attention to the patient's preoperative potassium levels along with their red blood cell counts especially in patients diagnosed with type 2 diabetes mellitus.