IS THE ANTIPROTEINURIC RESPONSE TO INHIBITION OF THE RENIN-ANGIOTENSIN SYSTEM LESS EFFECTIVE DURING THE NIGHT

Background. In glomerular disease proteinuria usually has a circadian pattern with maximum excretion during the day. Blockade of the renin-a ngiotensin system (RAS) results in a 50% reduction of proteinuria as m easured in 24-h urine collections. We questioned whether anti-proteinu ric treatment by blockade of the RAS is as effective during the day as during the night. Methods. We analysed data from two intervention stu dies on proteinuria in patients with non-diabetic renal disease. In th e first study, six hospitalized patients (proteinuria 5.8+/-2.9 g/day) were treated with the renin-inhibitor remikiren 600 mg o.d. during 8 days. In the second study eight ambulant patients (proteinuria 7.5+/-2 .7 g/day) were treated during 6 weeks with the ACE-inhibitor trandolap ril 4 mg o.d. Urine was collected in a day-and in a night-time portion . Results. Daytime proteinuria declined from 0.29+/-0.15 to 0.22+/-0.1 1 g/h (P < 0.05) during remikiren and from 0.33 +/- 0.14 to 0.16+/-0.0 8 g/h (P<0.05) during trandolapril. Night-time proteinuria, however, w as not significantly reduced from 0.23+/-0.11 to 0.19+/-0.11 g/h durin g remikiren and from 0.29+/-0.17 to 0.20+/-0.12 g/h during trandolapri l. Both interventions effectively lowered blood pressure during the da y as well as the night. Conclusion. In both studies relative nocturnal therapy resistance to the antiproteinuric effect of RAS blockade was found, despite 24-h efficacy of blood pressure effect. This may have c linical relevance because it contributes to rest-proteinuria and thus may affect long term renal function outcome. It may be worthwhile to e xplore alternative therapeutic regimens to improve the nocturnal antip roteinuric response.