Saudi Journal of Kidney Diseases and Transplantation

: 2012  |  Volume : 23  |  Issue : 6  |  Page : 1298--1299

IgM nephropathy: Clinical features and pathological findings in 36 patients

Muhammed Mubarak 
 Associate Professor, Histopathology Department, Sindh Institute of Urology and Transplantation, Karachi-74200, Pakistan

Correspondence Address:
Muhammed Mubarak
Associate Professor, Histopathology Department, Sindh Institute of Urology and Transplantation, Karachi-74200

How to cite this article:
Mubarak M. IgM nephropathy: Clinical features and pathological findings in 36 patients.Saudi J Kidney Dis Transpl 2012;23:1298-1299

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Mubarak M. IgM nephropathy: Clinical features and pathological findings in 36 patients. Saudi J Kidney Dis Transpl [serial online] 2012 [cited 2023 Feb 5 ];23:1298-1299
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To the Editor,

I have read with interest the article by Mokhtar published in a recent issue of your journal. [1] It describes the clinical and morphological features of a fairly common, but still controversial, entity of IgM nephropathy (IgMN) in 36 patients. Such studies are a welcome addition to the growing literature on this subject and will certainly contribute to the clarification of the status of the disease. However, in reviewing the available literature on IgMN, several difficulties are encountered. Many studies combine both children and adults in the same group, as has been done in the subject study. [2] This will not significantly affect the results if the major characteristics of the two groups are analyzed separately and the sample size of both age groups is large enough. However, in the subject study, adults are only five in number compared with 31 children. This would have obviously influenced the results of the study. The author could have easily excluded adults to make a homogeneous group of children. Many studies on IgMN did not specify precisely the extent, distribution and intensity of staining of IgM or included in the later category biopsies with only trace positivity of IgM. [2] Hence, for a disease such as IgMN, which is at best still controversial, one has to be extremely scrupulous in the study design and methodology used to analyze the results if these are to prove useful for exact characterization of the disease. We have also published our experience in the largest study ever on this disease in children. [3] Fortuitously, many of the clinical and pathological features of our cohort are more or less similar to those reported in the subject study, except for the markedly higher rate (66%) of steroid resistance in the subject study. However, there are some points that need clarification for a better understanding of the disease in the above study, as given below:

The age of the patients should have been given as median with interquartile range (IQR) or mean (which has been used) with standard deviation (SD) to accurately reflect the possibly markedly skewed distribution of age in favor of children. The age in the subject study is given as mean in the results, but in the discussion the same figure is given as a median value for children, which is not correct.Obviously, the renal biopsy indications must have been different in the two age groups of patients. There is no information on this important aspect of the study. I suppose the steroid response patterns reported refer to pediatric cases and not to the adolescents or adults, but a clarification of these will be helpful in better understanding the natural history of the disease.The author concludes that there is increased risk of progression to focal segmental glomerulosclerosis (FSGS), which is actually not supported by the evidence in the author's study. There were no re-biopsies performed in any of the 36 cases to confirm this finding. The initial presentation of IgMN with FSGS is one thing and the progression to FSGS is another thing, and these do not necessarily represent the same phenomenon.The author also concludes that IgMN is more common in children. Although true, this is not proved from this study, in which the total number of biopsies according to age groups are not provided.The author also concludes that IgMN has distinctive clinico-pathological findings, which support IgMN as a distinct entity. As a matter of fact, there is no specific clinical or pathological feature of IgMN except for the immunoflourescence (IF) findings, and there is significant overlap with the lesions of minimal change disease and FSGS. [4] Alternatively, it is the response to treatment and the natural course of the disease that support its distinctive nosologic status.There is also no clear information on the timing of treatment of the condition, as to whether it was offered before or after biopsy?C1q is also an important immuno-reactant for renal panel IF test, and potentially important from studying the pathogenesis of the disease, but has not been tested in the study. [5]


1Mokhtar GA. IgM nephropathy: clinical features and pathological findings in 36 patients. Saudi J Kidney Dis Transpl 2011;22:969-75.
2Al Eisa A, Carner JE, Lirenman DS, Magil AB. Childhood IgM nephropathy: comparison with minimal change disease. Nephron 1996; 72:37-43.
3Mubarak M, Kazi JI, Malik S, Lanewala A, Hashmi S. Clinicopathologic characteristics and steroid response of IgM nephropathy in children presenting with idiopathic nephrotic syndrome. APMIS 2011;119:180-6.
4Myllymaki J, Saha H, Mustonen J, Helin H, Pasternack A. IgM nephropathy: Clinical picture and long term prognosis. Am J Kidney Dis 2003;41:343-50.
5Hsu HC, Chen WY, Lin GJ, et al. Clinical and immunopathologic study of mesangial IgM nephropathy: Report of 41 cases. Histopathology 1984;8:435-46.