Evaluation of point-of-care tests for detecting microalbuminuria in diabetic patients

Abstract

Background: Microalbuminuria, the presence of low levels of albumin in the urine, indicates renal damage and is recognised as a risk factor for the progression of renal and cardiovascular disease. Several international scientific bodies recommend microalbuminuria screening. Point-of-care testing (POCT) of microalbuminuria allows immediate identification of risk, and monitoring of treatment effects. In this study, two POCT instruments were evaluated as microalbuminuria screening methods. Method: Spot urine specimens from diabetic patients were analysed with the quantitative HemoCue^® urine albumin analyser (n = 245), and the semiquantitative Clinitek^® microalbumin urine dipstick (n = 204). These results were compared to the respective data for laboratory-determined albumin (nephelometry), creatinine (modified Jaffe) and albumin-to-creatinine ratio (ACR). Results: Linear regression analysis demonstrated a good correlation for the HemoCue® urine albumin with the laboratorydetermined albumin concentration (y = 0.8557x + 0.2487y, r = 0.97). The sensitivities for the HemoCue^® and Clinitek^® POCT systems were 79.6% and 83.8%, and the specificities 97.1% and 93.8% respectively. Positive and negative predictive values for the HemoCue^® were 95.6% and 85.8%, and were 88.6% and 91.0% the Clinitek^®. The repeatability of both instruments was excellent. Both instruments are easy to use, and more cost-effective than the laboratory methods for albumin and ACR. Conclusion: Both the HemoCue^® and the Clinitek® microalbumin POCT systems for albuminuria are easy to use and inexpensive, and are adequately accurate as a screening method. Although the HemoCue^® POCT system measures only urine albumin concentration, its sensitivity and specificity compared well with that of the Clinitek^® POCT system, which determines the ACR.

Keywords: microalbuminuria, point-of-care testing, HemoCue^®, Clinitek^®, urinary albumin excretion