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.

Georg Ganter--a pioneer of peritoneal dialysis and his tragic academic demise at the hand of the Nazi regime.

First reports in German literature on the effective removal of uremic toxins by means of extracorporeal hemodialysis in bi-nephrectomized, acute uremic dogs were given by Heinrich Necheles and Georg Haas. These methods were viewed with great scepticism by Georg Ganter who criticized in particular the extensive operative procedure by use of the femoral artery and vein, the size and fragility of the dialysers, as well as the potential toxic effects of the anticoagulant hirudin. As an alternative approach, he suggested the use of the peritoneum as an especially large endogenous dialysis membrane. In 1923, in experiments on ureter-ligated guinea pigs and rabbits, he demonstrated that the single or repeated instillation (after effective draining) of physiological NaCl solution improves both the symptoms of uremia and the blood urea nitrogen level. In patients this new procedure was implemented only sporadically and in the form of a single fluid instillation after a first observation in a uremic patient where a pleura exudate was substituted: in a female patient with acute uremia as a consequence of a ureter occlusion, due to uterus carcinoma, and in a patient with a diabetic coma. In spite of these limited experiences, Ganter was convinced of the superiority of his method over the troublesome hemodialysis therapy and recommended its broader clinical application.

Folate metabolism in renal failure.

In most patients with chronic kidney disease, provision of sufficient human recombinant erythropoietin (rHuEPO) and iron replacement therapy will effectively correct renal anaemia. Folate deficiency has been implicated as a contributory factor in renal anaemia and hyporesponsiveness to rHuEPO treatment. As such, the necessity of regular folate supplementation has been debated over the last decade. Although folate loss through dialysis is greater than by urinary excretion, these losses are easily balanced by a normal mixed diet containing 60 g protein/day. Thus, unless patients show significant folate depletion, additional supplementation of folic acid does not appear to have a beneficial effect on erythropoiesis or on responsiveness to rHuEPO therapy. However, a diagnosis of folate deficiency should be considered in patients with chronic renal insufficiency and significant elevation in mean cell volume or hypersegmented polymorphonuclear leucocytes; in patients with malnutrition or a history of alcohol abuse, or in patients hyporesponsive to rHuEPO treatment, especially when accompanied by macrocytosis. Measurements of serum folate are not necessarily indicative of tissue folate stores and red blood cell (RBC) folate measures provide a more accurate picture. Low RBC folate concentrations in these patients indicate the need for folate supplementation. Folate supplementation can also reduce elevated levels of homocysteine in dialysis patients, which may contribute to the high cardiovascular morbidity prevalent in these individuals. High-dose folate therapy (5-15 mg/day) has been shown to reduce plasma homocysteine levels by 25-30% and appears to be well tolerated provided the patient has adequate vitamin B(12) stores. Although long-term benefits of this intervention for cardiovascular protection and patient survival have yet to be established, folic acid is considered a relatively non-toxic and well-tolerated vitamin.