IgA nephropathy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Synonyms and keywords: IgA nephritis; IgAN; Berger's disease; synpharyngitic glomerulonephritis
Therapy
The ideal treatment for IgAN would remove IgA from the glomerulus and prevent further IgA deposition. This goal still remains a remote prospect. There are a few additional caveats that have to be considered while treating IgA nephropathy. IgA nephropathy has a very variable course, ranging from a benign recurrent hematuria up to a rapid progression to chronic renal failure. Hence the decision on which patients to treat should be based on the prognostic factors and the risk of progression. Also, IgA nephropathy recurs in transplants despite the use of ciclosporin, azathioprine or mycophenolate mofetil and steroids in these patients. There are persisting uncertainties, due to the limited number of patients included in the few controlled randomized studies performed to date, which hardly produce statistically significant evidence regarding the heterogeneity of IgA nephropathy patients, the diversity of study treatment protocols, and the length of follow-up.
Patients with isolated hematuria, proteinuria < 1 g/day and normal renal function have a benign course and are generally just followed up annually. In cases where tonsillitis is the precipitating factor for episodic hematuria, tonsillectomy has been claimed to reduce the frequency of those episodes. However, it does not reduce the incidence of progressive renal failure[3]. Also, the natural history of the disease is such that episodes of frank hematuria reduce over time, independent of any specific treatment. Similarly, prophylactic antibiotics have not been proven to be beneficial. Dietary gluten restriction, used to reduce mucosal antigen challenge, also has not been shown to preserve renal function. Phenytoin has been also been tried without any benefit[4].
A subset of IgA nephropathy patients, who have minimal change disease on light microscopy and clinically have nephrotic syndrome, show an exquisite response to steroids, behaving more or less like minimal change disease. In other patients, the evidence for steroids is not compelling. Short courses of high dose steroids have been proven to lack benefit. However, in patients with preserved renal function and proteinuria (1-3.5 g/day), a recent prospective study has shown that 6 months regimen of steroids may lessen proteinuria and preserve renal function[5]. However, the risks of long-term steroid use have to be weighed in such cases. It should be noted that the study had 10 years of patient follow-up data, and did show a benefit for steroid therapy; there was a lower chance of reaching end-stage renal disease (renal function so poor that dialysis was required) in the steroid group. Importantly, angiotensin-converting enzyme inhibitors were used in both groups equally.
Cyclophosphamide had been used in combination with antiplatelets / anticoagulants in unselected IgA nephropathy patients with conflicting results. Also, the side effect profile of this drug, including long term risk of malignancy and sterility, made it an unfavorable choice for use in young adults. However, one recent study, in a carefully selected high risk population of patients with declining GFR, showed that a combination of steroids and cyclophosphamide for the initial 3 months followed by azathioprine for a minimum of 2 years resulted in a significant preservation of renal function [6]. Other agents such as mycophenolate mofetil, ciclosporin and mizoribine have also been tried with varying results.
A study from Mayo Clinic did show that long term treatment with omega-3 fatty acids results in reduction of progression to renal failure, without, however, reducing proteinuria in a subset of patients with high risk of worsening kidney function[7]. However, these results have not been reproduced by other study groups and in two subsequent meta-analyses [8][9]. However, fish oil therapy does not have the drawbacks of immunosuppressive therapy. Also, apart from its unpleasant taste and abdominal discomfort, it is relatively safe to consume.
The events that tend to progressive renal failure are not unique to IgA nephropathy and non-specific measures to reduce the same would be equally useful. These include low-protein diet and optimal control of blood pressure. The choice of the antihypertensive agent is open as long as the blood pressure is controlled to desired level. However, Angiotensin converting enzyme inhibitors and Angiotensin II receptor antagonists are favoured due to their anti-proteinuric effect.
References
- ^ Xie Y, Chen X, Nishi S, Narita I, Gejyo F. Relationship between tonsils and IgA nephropathy as well as indications of tonsillectomy. Kidney Int. 2004;65(4):1135-44. PMID 15086452
- ^ Clarkson AR, Seymour AE, Woodroffe AJ, et al. Controlled trial of phenytoin therapy in IgA nephropathy. Clin Nephrol. 1980;13(5):215-8. PMID 6994960
- ^ Kobayashi Y, Hiki Y, Kokubo T, et al: Steroid therapy during the early stage of progressive IgA nephropathy: A 10-year follow-up study. Nephron. 1996;72:237-242 PMID 8684533.
- ^ Ballardie FW, Roberts IS: Controlled prospective trial of prednisolone and cytotoxics in progressive IgA nephropathy. J Am Soc Nephrol. 2002;13:142-148 PMID 11752031.
- ^ Donadio JV Jr, Bergstralh EJ, Offord KP, Spencer DC, Holley KE: A controlled trial of fish oil in IgA nephropathy. Mayo Nephrology Collaborative Group.N Engl J Med. 1994;331(18):1194-9 PMID 7935657
- ^ Strippoli G, Mano C, Schena F. An ‘evidence-based’ survey of therapeutic options for IgA nephropathy: assessment and criticism. Am J Kidney Dis. 2003;41:1129–1139 PMID 12776264
- ^ Dillon JJ. Fish oil therapy for IgA nephropathy: efficacy and interstudy variability. J Am Soc Nephrol. 1997;8:1739–1744 PMID 9355077
- ^ Bartosik LP, Lajoie G, Sugar L, Cattran DC. Predicting progression in IgA nephropathy. Am J Kidney Dis. 2001;38(4):728-35. PMID 11576875