Background: In Mexico, diabetes mellitus type 2 and hypertension are leading causes of end-stage renal disease. Diagnosis of early renal damage with detection of microalbuminuria (microAlbU) is fundamental for treatment and prevention, and so avoiding the catastrophes of renal failure. For screening purposes, several simplified tests, including dipstick methods, fulfill the accuracy requirements for microAlbU detection compared with gold standards; however, no study has established the reliability of such tests in our setting.
Aim: To evaluate the utility of micraltest II as a screening test for microAlbU compared with nephelometry in patients with diabetes mellitus type 2 and non-diabetic patients with essential hypertension.
Patients and methods: Patients with diabetes mellitus type 2 as well as patients with essential hypertension of any age, sex and time of evolution, attending to three primary health-care units (UMF No. 3, 92 and 93, Guadalajara, Jalisco) were included. Patients with transitory albuminuria, secondary hypertension and serum creatinine > or = 2 mg/dL were excluded. Micraltest II was performed in the first morning urine sample, and nephelometry was performed in a 24-h urine collection. Diagnostic accuracy of the dipstick test was then determined.
Results: 245 patients were studied: 71 (29%) were diabetics without hypertension, 95 (39%) were diabetics with hypertension, and 79 (32%) had only essential hypertension. In diabetic patients, micraltest II sensitivity was 83%, specificity 96%, and positive and negative predictive values were 95% and 88%, respectively. Correlation between nephelometry and micraltest II results was 0.81 (p < 0.001). The best cut-off point for microAlbU was 30.5 mg/L, and area under the curve (+/- SEM) was 0.91 +/- 0.03 (confidence interval 95%: 0.85-0.96). In non-diabetic patients with essential hypertension, micraltest II sensitivity was 75%, specificity 95%, and positive and negative predictive values were 43% and 99%, respectively. Correlation between nephelometry and micraltest II results was 0.43 (p < 0.001). The best cut-off point for microAlbU was 28.2 mg/L, and area under the curve was 0.85 +/- 0.13 (0.60-1.10).
Conclusion: Micraltest II dispstick is a rapid, valid and reliable method for albuminuria screening in patients with diabetes mellitus type 2 and in those non-diabetic patients with essential hypertension in our setting.