to continued glomerular injury that potentially could result

to establish an autoimmune pathogenesis for PSGN.However, newer serologic and immunopathologic data now suggest the pathogenesis is more complicated and implicate primarily the alternative C pathway (AP) in these diseases. This supports considering many cases of PSGN as one part of a sp??trum of that includes some C3-dominant IRGNs and the r??ently r??ognized “C3 nephropathies” rather than as a traditional BSA-like immune complex (IC) disease. Thus we now r??ognize a sp??trum of overlapping entities that include classic PSGN, IRGN, atypical PSGN, and C3 nephropathies in which inf??tions are often pr??ipitating events but deposition of CICs seems unlikely to be the major m??hanism, and host abnormalities in C activation9and regulation may play more important roles. Whether these newer m??hanisms are operative only in unusual cases or play a more generalized role in PSGN awaits further study.Persistent (chronic) glomerulonephritis Most types of GN will enter a chronic or persistent phase. Often such patients are at risk for continued glomerular injury that potentially could result in ESRD. Commonly, patients with GN that began in childhood or adolescence do not reach ESRD until adulthood. Progression to ESRD in adolescents with chronic GN may be delayed or even avoided with attention to the principles of renoprot??tion 26. This attention involves aggressive control of hypertension and treatment of proteinuria for both normotensive and hypertensive patients with an ACEi or an ARB. These agents are eff??tive in reducing proteinuria in virtually all forms of chronic GN. Many adolescents and young adults exhibit poor compliance with regard to taking their medications. The primary care physician plays an important role in monitoring control of hypertension, encouraging compliance with medications, and stressing the importance of regular follow-up by the nephrologist. In addition, the physician should be aware of ACEi fetopathy as a major risk for pregnant adolescents so that the drug may be stopped immediately if the patient b??omes pregnant. ACEi and ARB therapy should be used cautiously in adolescents at risk for dehydration, particularly in the football player involved in summer practice who has an increased risk for development of prerenal azotemia.Rapidly progressive glomerulonephritis RPGN may be diagnosed in the adolescent who presents with macroscopic hematuria and is found to have an elevated serum creatinine that continues to rise on a daily basis. Nonsp??ific symptoms such as fatigue and lethargy are common. Often the macroscopic hematuria persists until well after the initiation of treatment with intravenous methylprednisolone. Typically, more than 50% of the glomeruli should be aff??ted with crescents for a case to be classified as RPGN 8. All of the immunologically mediated types of GN may present as RPGN, but the types most frequently associated with it are antiglomerular basement membrane (anti-GBM) disease, antineutrophil cytoplasmic autoantibodies (ANCA) GN, and Henoch-Schfnlein purpura nephritis (HSPN). PSAGN may also have crescent formation and in some cases will fit the definition of RPGN. The rarity of RPGN in children and adolescents is illustrated by a pediatric series that found crescents in 56 of 372 biopsy sp??imens, with only two meeting criteria for classification as RPGN 9. Often pediatric nephrologists will treat patients with fewer than 50% of glomeruli aff??ted with crescents as if they had RPGN. Despite aggressive therapy, the outcome is often progression to ESRD. Early diagnosis and aggressive treatment are the most important factors in preservation of renal function.10Poststreptococcal acute glomerulonephritis Early descriptions of PSAGN were based on the description of epidemics or clusters of cases usually related to pyoderma, with many cases being asymptomatic 10–12. The peak age at occurrence was 4 to 5 years; few cases were diagnosed in adolescents. In the latest pediatric series from Memphis, only 11% were age 13 or older (S. Roy, personal communication, 2004). At the present time, cases tend to occur more sporadically, with more due to pharyngitis than to pyoderma, and the incidence in both the United States and other countries is d??lining 13–15.Hutt et al. (1958) have studied renal biopsy sp??imens from I5 patients diagnosed clinically as having acute glomerulonephritis (three had no proteinuria or haematuria). They found a reasonable correlation between the severity of the clinical and of the histological features. The glomerular tuft lesions were those which have been described previously in post-mortem material but the three atypical cases mentioned above only had minor changes in the cells of Bowman’s capsule. Impairment of renal ability to concentrate was correlated with the severity of the tubular lesions. Brun et al. (1958) obtained biopsy sp??imens from 9 to 49 days after the onset of symptoms in I3 patients with acute glomerulonephritis. Again, there was a good correlation between the clinical and histological features. The finding of generalized ‘ irreversible’ changes in the glomeruli was considered to indicate a hopeless prognosis in six cases. The authors were surprised to observe ‘ chronic’ collagenous glomerular lesions in some sp??imens; these may have been due to previous renal disease or it is possible that such lesions develop more rapidly than was previously thought possible. The demonstration of intense inflammatory and n??rotic lesions in the kidneys of patients with severe acute nephritis is not unexp??ted. It will be of more value if structural changes can be r??ognized which will allow differentiation between mild cases who will r??over and mild cases who will progress slowly to renal failure. Hutt et al. (1958) obtained one sp??imen six weeks after the onset of oedema and haematuria and about four weeks after r??overy had commenced; only slight proliferative changes and a patchy increase of periodicacid-Schiff staining fibrils were present in the glomeruli. The author has observed similar lesions in sp??imens from two patients r??overing from the acute stage of the disease (Fig. 6); one of them has made a complete r??overv, the other still has slight proteinuria one year after biopsy. Perhaps the finding of collagenous glomeruli or diffuse interstitial fibrosis will be correlated with failure to r??over and a slowly progressive course, when more patients have been studied. Farquhar et al. (I957 b and c) have described the el??tronmicroscopic glomerular lesions in acute glomerulonephritis. In the early stages the hypercellularity was found to be mainly due to an increase in the number of the endothelial cells. The cytoplasm of both epithelial and endothelial cells