AN IGM NEPHROPATHY DIAGNOSED IN THE CONTEXT OF AN ACUTE VIRAL GASTROENTERITIS
Doenças Renais - E-Poster
Congresso ID: P801 - Resumo ID: 516
Serviço de Nefrologia do Hospital Beatriz Ângelo
Beatriz Donato, Adriana Paixão Fernandes, Sara Lamarosa Fernandes, Luís Pedro Falcão, Catarina Teixeira, Ana Cortesão Costa, Mário Raimundo, Sónia Silva, Edgar Almeida
Introduction
IgM nephropathy (IgMN) is a rare glomerulonephritis, considered to be a bridge between minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS).Light microscopy (LM) and immunofluorescence (IF) are mandatory for the diagnosis.In contrast to the consistent deposits of IgM on IF, the LM findings are quite heterogeneous.IgMN can present as nephrotic syndrome or,less commonly,with hemato-proteinuria.Corticosteroids constitute the mainstay of treatment,as in MCD and FSGS.
We present a case report in which the absence of normalization of serum creatinine (sCr) after dehydration secondary to acute viral gastroenteritis and the abnormal urinalysis lead to the diagnosis of a chronic kidney disease (CKD).
Clinical case
A 18-year-old caucasian male presented with one-day history of diarrhea,vomiting and epidemiological context for AVG.Upon admission,physical exam was notable for dehydration,otherwise unremarkable.Initial laboratory data revealed leukocytosis with neutrophilia and impaired renal function(sCr of 1.53mg/dL). Acute gastroenteritis of viral etiology was admitted with prerenal acute kidney injury (AKI).An adequate hydration was done,with improvement of renal function (at discharge, sCr was 1.12mg/dL).Urinalysis disclosed hemato-proteinuria and renal ultrasound showed kidneys with normal size,but with a slight increase in echogenicity.
In the follow-up after discharge, he was asymptomatic,normotensive,without edema or macroscopic urine changes.There was persistent hemato-proteinuria and the 24 hours proteinuria was 1.35g/dL.Anti-nuclear and anti-double stranded DNA antibodies and rheumatoid factor were negative and complement (C3 and C4) and IgA, IgG and IgM were within the normal range.Serological markers of hepatitis B and C virus and HIV were negative, as well as the antistreptolysin O test.The protein electrophoresis was normal.He started on ramipril,with slight improvement of proteinuria (1g/24 hours),but no improvement in renal function.A renal biopsy was performed and LM showed a discrete increase in mesangial axis with preserved capillary walls and free Bowman spaces.Very small areas of fibrosis and tubular atrophy at interstitial level were observed.IF was positive for glomerular imune deposits IgM(++).These findings were compatible with the diagnosis of IgMN.Given the stability of renal function and the absence of nephrotic proteinuria, there was no indication for immunosuppression.The patient was followed-up every 6-month with supportive treatment based on inhibitors of angiotensin converting enzyme and salt restriction.After a 3-year follow-up, he is clinically stable,with sCr 0.94 mg/dL and 24hours proteinuria 413mg/dL.
Discussion
This case illustrates the importance of urinalysis and checking the renal function in patients recovering from AKI. The clinical suspicion lead to early diagnosis of IgMN, in which timely management helps improve outcome, by delaying the natural progression of CKD.
IgM nephropathy (IgMN) is a rare glomerulonephritis, considered to be a bridge between minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS).Light microscopy (LM) and immunofluorescence (IF) are mandatory for the diagnosis.In contrast to the consistent deposits of IgM on IF, the LM findings are quite heterogeneous.IgMN can present as nephrotic syndrome or,less commonly,with hemato-proteinuria.Corticosteroids constitute the mainstay of treatment,as in MCD and FSGS.
We present a case report in which the absence of normalization of serum creatinine (sCr) after dehydration secondary to acute viral gastroenteritis and the abnormal urinalysis lead to the diagnosis of a chronic kidney disease (CKD).
Clinical case
A 18-year-old caucasian male presented with one-day history of diarrhea,vomiting and epidemiological context for AVG.Upon admission,physical exam was notable for dehydration,otherwise unremarkable.Initial laboratory data revealed leukocytosis with neutrophilia and impaired renal function(sCr of 1.53mg/dL). Acute gastroenteritis of viral etiology was admitted with prerenal acute kidney injury (AKI).An adequate hydration was done,with improvement of renal function (at discharge, sCr was 1.12mg/dL).Urinalysis disclosed hemato-proteinuria and renal ultrasound showed kidneys with normal size,but with a slight increase in echogenicity.
In the follow-up after discharge, he was asymptomatic,normotensive,without edema or macroscopic urine changes.There was persistent hemato-proteinuria and the 24 hours proteinuria was 1.35g/dL.Anti-nuclear and anti-double stranded DNA antibodies and rheumatoid factor were negative and complement (C3 and C4) and IgA, IgG and IgM were within the normal range.Serological markers of hepatitis B and C virus and HIV were negative, as well as the antistreptolysin O test.The protein electrophoresis was normal.He started on ramipril,with slight improvement of proteinuria (1g/24 hours),but no improvement in renal function.A renal biopsy was performed and LM showed a discrete increase in mesangial axis with preserved capillary walls and free Bowman spaces.Very small areas of fibrosis and tubular atrophy at interstitial level were observed.IF was positive for glomerular imune deposits IgM(++).These findings were compatible with the diagnosis of IgMN.Given the stability of renal function and the absence of nephrotic proteinuria, there was no indication for immunosuppression.The patient was followed-up every 6-month with supportive treatment based on inhibitors of angiotensin converting enzyme and salt restriction.After a 3-year follow-up, he is clinically stable,with sCr 0.94 mg/dL and 24hours proteinuria 413mg/dL.
Discussion
This case illustrates the importance of urinalysis and checking the renal function in patients recovering from AKI. The clinical suspicion lead to early diagnosis of IgMN, in which timely management helps improve outcome, by delaying the natural progression of CKD.