Mass-screening for early detection of renal disease: benefits and limitations of self-testing for proteinuria.

INTRODUCTION

Chronic kidney diseases are of growing importance for our health system. With regard to the high number of undetected cases, screening programs provide opportunities for an early to detect and treat patients.

METHODS

With the support of local newspapers, we performed a mass screening of the citizens of Würzburg, Germany. One hundred thousand dipsticks for proteinuria were distributed. Citizens were invited to self-test their urine and to report the results to the organizing centre.

RESULTS

We received information for approximately 22% of the distributed dipsticks. Positive tests results numbered 2,458 after removal of 309 positive results for pre-diagnosed renal diseases. From family doctors, we obtained data for control investigations of 856 dipstick-positive subjects. In 104 of them, chronic proteinuria could be confirmed, due to essential hypertension (n=47), pyelo/interstitial nephritis (n=26), diabetic nephropathy (n=20), glomerulonephritis (n=4), nephrolithiasis (n=4), hypernephroma (n=2) and polycystic kidney disease (n=1).

DISCUSSION

The benefit of self-testing was an unexpectedly high compliance, even in males. However, a great number of abnormal tests could not be confirmed by family doctors, possibly owing to the time variation in urine testing (early-morning urine in the self-test vs. daytime testing by the physician), the high variability of urinary protein excretion and a large number of false-positive tests in the inexperienced participants.

CONCLUSION

Mass screening for proteinuria with self-testing enhances the awareness of renal diseases and improves the chances for an early diagnosis and therapy. Limitations are the frequent overdiagnosis of proteinuria due to minimal colour changes in the dipsticks.