DIAGNOSIS AND MANAGEMENT OF GLOMERULAR DISEASES

Appropriate treatment for glomerular diseases requires timely, accurate, and precise diagnosis. The diagnosis of glomerular diseases is challenging because the clinical manifestations are extremely varied, different glomerular diseases manifest the same clinical features, and a specific form of glomerular disease can manifest different clinical features in different patients or even in the same patient at different times Table 1, Table 2. Renal biopsy often is required for definitive diagnosis, although, occasionally, clinical signs and symptoms combined with laboratory data allow a presumptive diagnosis that is adequate for management decisions. For example, a young child with pure nephrotic syndrome who enters remission with corticosteroid therapy can be reasonably presumed to have minimal change glomerulopathy; a patient with evidence for a recent streptococcal pharyngitis or pyoderma who develops acute nephritis with hypocomplementemia can be reasonably presumed to have poststreptococcal glomerulonephritis. A renal biopsy also may not be warranted when the differential diagnosis consists predominantly of diseases that would not require immediate therapeutic intervention. For example, a patient with asymptomatic glomerular hematuria with less than 1 g/day proteinuria most likely has thin basement membrane nephropathy or mild IgA nephropathy. The former is a benign process that warrants no treatment, and the latter usually is an indolent disease with no standard treatment, although fish oil may have a beneficial effect. In many patients with clinical evidence for glomerular disease, however, renal biopsy evaluation by a nephropathologist is required for a definitive diagnosis, for accurate prognostication, and for determination of the appropriate therapeutic approach. Early and accurate diagnosis of aggressive forms of glomerular disease and timely initiation of treatment are critically important to good outcome. For example, a few days' delay in the institution of proper treatment in a patient with rapidly progressive crescentic glomerulonephritis can dramatically affect the likelihood of long-term preservation of renal function. This article presents an approach for diagnosing glomerular diseases, for determining the prognosis, and for designing an appropriate management strategy. The final resolution of the differential diagnosis often is made by a nephrologist or nephropathologist; however, primary care physicians must be capable of recognizing the signs and symptoms of glomerular disease and formulating a differential diagnosis that correctly indicates whether or not, and how quickly, a patient should be referred to a nephrologist.