IgM nephropathy: clinical picture and long-term prognosis.
BACKGROUND
Immunoglobulin M (IgM) nephropathy is an idiopathic glomerulonephritis with mesangial hypercellularity and diffuse IgM deposits.


METHODS
We studied clinical presentation, morphological findings, and prognostic factors in 110 patients with IgM nephropathy without systemic diseases. The series included both pediatric and adult patients with nephrotic syndrome (NS) or minor urinary abnormalities.


RESULTS
Mean postbiopsy follow-up was 8 years. During 15 years of follow-up, 36% of patients developed renal insufficiency and 23% reached end-stage renal failure. In multivariate analysis, hypertension at the time of renal biopsy was the only significant risk factor for renal insufficiency. Of histological parameters, interstitial fibrosis had the strongest prognostic value. Hypertension was diagnosed in 50% of patients with a postbiopsy follow-up of 15 years. Twenty-nine percent of nephrotic patients had disease resistant to corticosteroids, whereas 80% of patients with steroid-sensitive disease were steroid dependent. Eleven patients, 8 patients with NS and 3 patients with asymptomatic proteinuria, underwent repeated renal biopsy. In five samples, typical morphological characteristics of focal and segmental glomerulosclerosis were seen.


CONCLUSIONS
We propose that IgM nephropathy can be divided into two subgroups with similar renal biopsy findings, but differences in sex distribution and initial presentation.
Myllymäki
Juhani
J
Medical School, University of Tampere; and Departments of Medicine and Pathology, Tampere University Hospital, Tampere, Finland. lljumu@uta.fi
Saha
Heikki
H
Mustonen
Jukka
J
Helin
Heikki
H
Pasternack
Amos
A
D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D005921:Glomerulonephritis / Q000188:drug therapy / Q000453:epidemiology* / Q000473:pathology* / Q000652:urine; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007223:Infant; D007668:Kidney / Q000187:drug effects / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011379:Prognosis; D011507:Proteinuria / Q000188:drug therapy / Q000453:epidemiology / Q000473:pathology; D012307:Risk Factors
D000305:Adrenal Cortex Hormones; D007075:Immunoglobulin M; D007166:Immunosuppressive Agents