IgA nephropathy natural history, complications and prognosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Natural History
Since IgA nephropathy commonly presents without symptoms through abnormal findings on urinalysis, there is considerable possibility for variation in any population studied depending upon the screening policy. Similarly, the local policy for performing kidney biopsy assumes a critical role; if it is a policy to simply observe patients with isolated hematuria, a group with a generally favourable prognosis will be excluded. If, in contrast, all such patients are biopsied, then the group with isolated microscopic hematuria and isolated mesangial IgA will be included and ‘improve’ the prognosis of that particular series.
Nevertheless, IgA nephropathy, which was initially thought to be a benign disease, has been shown to have a not-so-benign long term outcome. Though most reports describe IgA nephropathy as having an indolent evolution towards either healing or renal damage, a more aggressive course is occasionally seen associated with extensive crescents, and presenting as acute renal failure. In general, the entry into chronic renal failure is slow as compared to most other glomerulonephritis – occurring over a time scale of 30 years or more (in contrast to the 5 to 15 years in other ğğglomerulonephritisüü). This may reflect the earlier diagnosis made due to frank hematuria.
Complete remission, i.e. a normal urinalysis, occurs rarely in adults, in about 5% of cases. Thus, even in those with normal renal function after a decade or two, urinary abnormalities persist in the great majority. In contrast, 30 – 50% of children may have a normal urinalysis at the end of 10 years. However, given the very slow evolution of this disease, the longer term (20 – 30 years) outcome of such patients is not yet established.
Overall, though the renal survival is 80 – 90% after 10 years, at least 25% and may be up to 45% of adult patients will eventually develop end stage renal disease.
Complications
Prognosis
Male gender, proteinuria (especially > 2 g/day), hypertension, smoking, hyperlipidemia, older age, familial disease and elevated creatinine concentrations are markers of a poor outcome. Frank hematuria has shown discordant results with most studies showing a better prognosis, perhaps related to the early diagnosis, except for one group which reported a poorer prognosis. Proteinuria and hypertension are the most powerful prognostic factors in this group[2]. There are certain other features on kidney biopsy such as interstitial scarring which are associated with a poor prognosis. ACE gene polymorphism has been recently shown to have an impact with the DD genotype associated more commonly with progression to renal failure.