IgA nephropathy in children

Guidance of clinical management for patients with tonsillar focal disease

Tonsillar focal diseases (TFDs) are defined as "diseases caused by organic and/or functional damage in organs distant from tonsil, and the disease outcome is improved by tonsillectomy." Although several reports and reviews have shown the efficacy of tonsillectomy for TFDs, no guidelines for the clinical management of the diagnosis and treatment of TFDs have been reported. Therefore, the Society of Stomato-pharyngology established a committee to guide the clinical management of patients with TFDs, and the original guide was published in May 2023. This article summarizes the English version of the manuscript. We hope that the concept of TFDs will spread worldwide, and that one as many patients with TFDs will benefit from tonsillectomy.

Urinary epidermal growth factor predicts complete remission of proteinuria in Chinese children with IgA nephropathy

BACKGROUND

This study investigated the association between urinary epidermal growth factor (EGF) and complete remission (CR) of proteinuria in children with IgA nephropathy (IgAN).

METHODS

We included 108 patients from the Registry of IgA Nephropathy in Chinese Children. The urinary EGF at the baseline and follow-up were measured and normalized by urine creatinine (expressed as uEGF/Cr). The person-specific uEGF/Cr slopes were estimated using linear mixed-effects models for the subset of patients with longitudinal data of uEGF/Cr. Cox models were used to analyze the associations of baseline uEGF/Cr and uEGF/Cr slope with CR of proteinuria.

RESULTS

Patients with high baseline uEGF/Cr were more likely to achieve CR of proteinuria (adjusted HR 2.24, 95% CI: 1.05-4.79). The addition of high baseline uEGF/Cr on the traditional parameters significantly improved the model fit for predicting CR of proteinuria. In the subset of patients with longitudinal data of uEGF/Cr, high uEGF/Cr slope was associated with a higher likelihood of CR of proteinuria (adjusted HR 4.03, 95% CI: 1.02-15.88).

CONCLUSIONS

Urinary EGF may be a useful noninvasive biomarker for predicting and monitoring CR of proteinuria in children with IgAN.

IMPACT

High levels of baseline uEGF/Cr (>21.45 ng/mg) could serve as an independent predictor for CR of proteinuria. The addition of baseline uEGF/Cr on the traditional clinical pathological parameters significantly improved the fitting ability for the prediction of CR of proteinuria. Longitudinal data of uEGF/Cr were also independently associated with CR of proteinuria. Our study provides evidence that urinary EGF may be a useful noninvasive biomarker in the prediction of CR of proteinuria as well as monitoring therapeutic response, thus guiding treatment strategies in clinical practice for children with IgAN.

Efficacy of combination therapy for childhood complicated focal IgA nephropathy

BACKGROUND

Patients with immunoglobulin A nephropathy who present with focal mesangial proliferation (focal IgAN) can have a relatively good prognosis, and renin-angiotensin system inhibitor (RAS-i) is commonly used as the initial treatment. However, there are some complicated focal IgAN cases with resistance to RAS-i treatment or nephrotic-range proteinuria. Thus, combination therapy including corticosteroids is often used. This study aimed to evaluate the efficacy of combination therapy for complicated focal IgAN cases by comparing to diffuse mesangial proliferation (diffuse IgAN).

METHODS

We conducted a multicenter retrospective study on 88 children who received 2-year combination therapy. The participants were classified based on pathological severity: focal IgAN (n = 26) and diffuse IgAN (n = 62).

RESULTS

In total, 26 patients with focal IgAN and 52 with diffuse IgAN achieved proteinuria disappearance within 2 years (100 vs. 83.9%, P = 0.03). Moreover, the time to proteinuria disappearance was significantly shorter in the focal IgAN group than in the diffuse IgAN group (2.9 vs. 4.2 months, P < 0.01) and all patients with focal IgAN achieved proteinuria disappearance within 8 months. At the last observation (8.6 vs. 10.4 years, P = 0.13), only patients with diffuse IgAN (n = 12) had greater than stage 2 chronic kidney disease. In terms of irreversible adverse events, one patient exhibited cataracts.

CONCLUSION

Combination therapy was significantly effective in patients with complicated focal IgAN. Moreover, the long-term prognosis was good, and the duration of combination therapy for complicated focal IgAN can be decreased to reduce adverse events.

IgA Nephropathy in Children: A Multicenter Study in Poland

IgA nephropathy (IgAN) is the most common form of glomerulonephritis in pediatric population. The clinical presentation of the disease in children ranges from microscopic hematuria to end-stage kidney disease. The aim of the study was to retrospectively assess clinical and kidney biopsy features in children with IgAN. We assessed a cohort of 140 children, 88 boys, 52 girls with the diagnosis of IgAN in the period of 2000-2015, entered into the national Polish pediatric IgAN registry. The assessment included the following: proteinuria, hematuria, glomerular filtration rate (GFR), arterial blood pressure, and the renal pathological changes according to the Oxford classification and crescents formation, as modifiable and unmodifiable risk factors. The incidence of IgAN in Poland was set at 9.3 new cases per year. The mean age at onset of IgAN was 11.9 ± 4.3 years, and the most common presentation of the disease was the nephritic syndrome, recognized in 52 % of patients. Kidney biopsy was performed, on average, 1.3 ± 2.0 years after onset of disease. Based on the ROC analysis, a cut-off age at onset of disease for GFR <90 mL/min/1.73 m² (risk factor of progression) was calculated as 13.9 years. Unmodifiable lesions: segmental sclerosis, tubular atrophy/interstitial fibrosis (S1, T1-2) in the Oxford classification and crescents in kidney biopsy were significantly more common in Gr 1 (>13.9 years) compared with Gr 2 (<13.9 years), despite a significantly shorter time to kidney biopsy in the former. We conclude that IgAN in children may be an insidious disease. A regular urine analysis, especially after respiratory tract infections, seems the best way for an early detection of the disease.

Relationship between serum IgA/C3 ratio and severity of histological lesions using the Oxford classification in children with IgA nephropathy

BACKGROUND

The aim of this study was to evaluate the usefulness of serum immunoglobulin A/complement factor 3 (IgA/C3) ratio for predicting histological severity of kidney lesions in children with IgA nephropathy (IgAN) based on World Health Organization (WHO) and the Oxford classification (OC).

METHODS

We studied 89 children with IgAN with a mean age of 11.38 ± 4.1 years (range 2-18 years). Based on available medical records, we retrospectively evaluated clinical data, IgA/C3 ratio, and kidney biopsy findings using the five-grade WHO classification and the OC The mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental sclerosis (S), tubular atrophy/interstitial fibrosis (T) (MEST) score (absent = 0, present = 1) calculated as the sum of M+E+S+T ranging from 0 to 4.

RESULTS

Mean IgA/C3 ratio values were significantly higher (P < 0.05) in patients with M1, S1, and T1 compared with M0, S0, and T0, respectively (P < 0.05); there were no differences in the WHO classification. We found a significant positive correlation between the IgA/C3 ratio and proteinuria (r = 0.24) and determined optimal cutoff values of the IgA/C3 ratio, with a corresponding confidence interval for specific MEST scores.

CONCLUSIONS

The IgA/C3 ratio in children with IgAN may be a useful marker of the severity of lesions found in kidney biopsy as evaluated using the OC.

Clinicopathologic correlation and outcome of C1q nephropathy

BACKGROUND AND OBJECTIVES

The number of patients with C1q nephropathy (C1qN) in previous reports is small and the duration of follow-up is short. Our study describes the clinicopathologic correlation and clinical outcome through the mean follow-up period of 7.2 yr in 61 patients.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

Sixty-one patients, 1 to 67 yr of age, with C1qN were enrolled in this study.

RESULTS

According to presentation at onset, patients were divided into two groups: asymptomatic urinary abnormalities (asymptomatic) (n = 36) and nephrotic syndrome (NS) (n = 25). Light microscopy showed minimal change disease (MCD) in 46 patients (75%), mesangial proliferative glomerulonephritis in 7 (12%), and focal segmental glomerulosclerosis (FSGS) in 8 (13%). The prevalence of MCD was higher in the NS group than in the asymptomatic group. Nine patients in the asymptomatic group and all patients in the NS group were treated with prednisolone and/or cyclosporine. Normal urinalysis was found in 10 patients in asymptomatic group and 8 in NS group during the follow-up. Thirteen patients in the NS group were frequent relapsers at the latest follow-up. Three patients with FSGS developed chronic renal failure 8 to 15 yr after the diagnosis. C1q deposits disappeared in 3 of 8 patients receiving repeat biopsy, and 2 of these 3 showed FSGS.

CONCLUSIONS

The prognosis of C1qN is good, associated with MCD in a large number. In some patients, C1q deposits disappear through the follow-up period. FSGS may develop in some patients on repeat biopsies. Further investigation is critically needed to settle this issue.

Clinicopathologic correlation of C1q nephropathy in children

BACKGROUND

Clinicopathologic correlation of C1q nephropathy is clarified poorly. The aim of our study is to clarify clinicopathologic correlation in childhood C1q nephropathy.

METHODS

Thirty children aged 3 to 15 years who met criteria proposed by Jennette and Hipp were enrolled in this study.

RESULTS

According to their presentation at onset, children were divided into 2 groups: the asymptomatic urinary abnormalities (asymptomatic) group (n = 18) and the nephrotic syndrome (NS) group (n = 12). Light microscopy showed minimal change disease (MCD) in 22 children (73%), mesangial proliferative glomerulonephritis in 6 children (20%), and focal segmental glomerulosclerosis (FSGS) in 2 children (7%). Four children in the asymptomatic group and all children in the NS group were administered prednisolone and/or cyclosporine. Normal urinalysis results were found in 8 children in the asymptomatic group and 3 children in the NS group during the follow-up period of 3 to 15 years. Eight children in the NS group were frequent relapsers at the latest follow-up. Two children with FSGS (1 child, asymptomatic group; 1 child, NS group) received dialysis 10 and 15 years after the diagnosis. There were no differences in histological findings and clinical outcomes between the 2 groups. Four children with MCD in the NS group underwent a second biopsy. C1q deposits disappeared in 2 children, and 1 of these 2 children showed FSGS.

CONCLUSION

Childhood C1q nephropathy is found in a wide clinical spectrum. Some children showed disappearance of C1q deposits through the follow-up period. A large number of children with C1q nephropathy showed MCD. However, FSGS may develop in some children on repeated biopsy. Therefore, long-term follow-up is needed in children with C1q nephropathy.

Increased prevalence of anti-gliadin IgA-antibodies with aberrant duodenal histopathological findings in patients with IgA-nephropathy and related disorders

BACKGROUND

Antibodies present in coeliac disease may occur in IgA-nephropathy. This raises the question of food intolerance in the disease. Evidence for a true correlation between the two disorders has however been scarce.

DESIGN

Sera from 89 patients with IgA-nephropathy and 13 other patients with IgA deposits in the glomeruli of kidney biopsies were analysed for IgA-antibodies to gliadin, endomysium and tissue transglutaminase (92/102 patients).

RESULTS

Eleven out of 89 (12.4%) of the patients with IgA-nephropathy and five of the 13 others (38%) had elevated titres of IgA-antibodies to gliadin but, in all cases but one, normal IgA-antibodies to endomysium. Patients with IgA-nephropathy and elevated IgA-antibodies to gliadin had elevated total serum IgA more frequently than patients who had not (p<0.01). Two patients with IgA-nephropathy and one with Hennoch Schönlein's purpura had elevated IgA-antibodies to tissue transglutaminase. Small bowel biopsy in 7 out of 11 IgA-antibodies to gliadin positive patients with IgA-nephropathy was pathologic in three cases (two with Marsh I) . One patient with chronic glomerulnephritis also had Marsh I.

CONCLUSIONS

We found no increased frequency of verified coeliac disease in 89 patients with IgA-nephropathy. Two patients with IgA-nephropathy and one patient with chronic glomerulonephritis with IgA deposits in the kidney biopsy had a Marsh I histopathology. The findings suggest a possible link of celiac disease to IgA-nephropathy and a role for antibodies to food antigens in this disorder.

Value of urinary excretion of microalbumin in predicting glomerular lesions in children with isolated microscopic hematuria

Urinary microalbumin excretion was assessed in 76 children with asymptomatic microscopic hematuria in whom the presence of proteinuria, hypertension, reduced renal function, hypercalciuria, urinary tract infection or structural abnormality of the urinary tract had been excluded. All children underwent a percutaneous kidney biopsy to determine whether microalbumin excretion can be used as a marker to predict the source of hematuria. Microalbumin excretion was considered normal if the urinary ratio of microalbumin to creatinine (MA/Cr ug/mg) was < or =30. Twenty-two (29%) had microalbuminuria (MA/Cr 96+/-30 microg/mg) and 54 (71%) had normal albumin excretion (MA/Cr 13+/-2 microg/mg). Of those with normoalbuminuria, 38 (70%) had normal renal tissue, 15 (28%) thin glomerular basement membrane (TGBM) disease and 1 (2%) IgA nephropathy. In contrast, 20 (91%) of those with microalbuminuria had IgA nephropathy and 2 (9%) had TGBM disease. The mean urinary MA/Cr ratio for all IgA children was 89+/-32 microg/mg higher compared with a value for the children with TGBM disease (14 +/-3 microg/mg, P <0.001) or children whose renal biopsy appeared normal (11+/-2 microg/mg, P <0.001). Statistical analysis revealed no significant differences between the mean MA/Cr ug/mg ratio for children with TGBM disease and those with normal glomerular findings. Fourteen of the 20 children with IgA nephropathy who also had microalbuminuria were treated with an angiotensin-converting enzyme (ACE) inhibitor. Over a mean follow-up of 51 months, none developed overt proteinuia; hematuria resolved and microalbuminuria returned to normal in eight (57%) during therapy with the ACE-inhibitor. In contrast, hematuria persisted and prtoteinuria developed in the other untreated children. None of the children with TGBM disease developed overt proteinuria after a mean of 51 months. Hematuria was persistent in children with TGBM disease, but often resolved in those whose biopsies were completely normal. These data suggest that determination of urinary microalbumin excretion is warranted in the routine examination of children with isolated microscopic hematuria. Routine screening for microalbuminuria may help to identify a subgroup of patients with IgA nephropathy who are at high risk for progressive kidney disease and need more intensive therapy and closer follow-up.

Clinicopathological correlation of childhood IgA glomerulonephritis presenting diffuse endocapillary proliferation

The aim of the present study is to clarify the clinicopathological correlation of childhood IgA glomerulonephritis (GN) presenting diffuse endocapillary proliferation. Twenty-seven patients were used in the present study. The 27 patients were divided into three groups (mild, moderate and severe) according to the percentage of glomeruli displaying global endocapillary proliferation per total glomeruli at the first biopsy. The degree of both cellular crescent and lysis of the glomerular basement membrane (GBM) at the first biopsy was semiquantitatively evaluated. The degree of cellular crescent and lysis in the GBM was greater in the severe group than in the mild group. The degree of lysis of the GBM positively correlated with the degree of distribution of endocapillary proliferation. The degree of glomerular sclerosis at the second biopsy was greater in the severe group compared with the other two groups. The severity of cellular crescent at the first biopsy positively correlated with that of glomerular sclerosis at the second biopsy. Multiple logistic regression analysis indicated that the risk of glomerular sclerosis at the second biopsy was 19-fold higher in the odds ratio in the severe group compared with the mild group. In conclusion, the progression of glomerular sclerosis in serial biopsy is dependent on the degree of distribution of endocapillary proliferation and the severity of cellular crescents at the first biopsy in childhood IgA GN presenting diffuse endocapillary proliferation.

Incidence of pediatric IgA nephropathy

Immunoglobulin A (IgA) nephropathy progresses without apparent signs. The only available means of knowing the precise incidence of this disease in children is to analyze data from the school urinary screening system. Students between 6 and 15 years old with IgA nephropathy detected by school urinary screening from 1983 to 1999 in Yonago City, Japan, were examined. In addition, two hospitals with pediatric care units administered a questionnaire and patients with pediatric IgA nephropathy detected by means other than the school urinary screening program were recruited. Of 270,902 children examined by the school urinary screening system, 29 demonstrated suspected chronic nephritis on the basis of abnormal urinalysis and underwent renal biopsy procedures. Among the 29 children, 14 cases of IgA nephropathy were confirmed. During the same period, of the children examined by means other than the school screening program, 20 demonstrated suspected renal disease and underwent renal biopsies. Among these 20 children, 6 cases of IgA nephropathy were diagnosed. In all, 20 cases of pediatric IgA nephropathy were detected over the past 17 years. The incidence rate of pediatric IgA nephropathy was 4.5 cases/year per 100,000 children under 15 years. The incidence of pediatric IgA nephropathy is higher than that of idiopathic nephrotic syndrome.