PAEDIATRIC RENAL BIOPSIES IN EAST BOHEMIA . SINGLE CENTRE EXPERIENCE IN THE YEARS 1997 – 2008

Renal biopsy (RB) is a decisive diagnostic procedure in patients with renal disease. The indications for RB have changed over the years. The policy and threshold for performing may vary considerably among different centers and nephrologists. In general, there are five categories of indications (7, 9–10, 12, 16–18, 26, 27, 32, 33, 35): glomerular hematuria; non-nephrotic range protenuria; nephrotic syndrome; acute nephritic syndrome; acute or subacute renal failure of undetermined origin. In paediatric patients these indications further include: persistent hematuria of unknown origin; persistent proteinuria of unknown origin; steroid-resistant nephrotic syndrome; acute renal failure of unknown origin; familial nephritis; rapidly progressive glomerulonephritis; “atypical“ acute glomerulonephritis; suspected tubulointerstitial nephritis; nephropathies in systemic diseases (Lupus erythematosus, Henoch-Schoenlein purpura) (7, 12, 18, 19, 26, 27, 35). In paediatric nephrotic syndrome (NS) the indications are: congenital NS (occurring under 6 months of age); corticoresistant NS; corticodependent NS prior to cyclosporine A therapy; NS patients > 12 years of age; atypical signs (macroscopic hematuria, hypertension, acute renal failure, abnormal laboratory results such as low C3 complement serum levels) (7, 12, 17, 18, 26, 27, 33, 35). Several epidemiological data concerning RB in children have been published (1–8, 14–16,19–32, 35). In Czech Republic, a central registry incorporating both adults and children has been established in 1993. By the year 2000 it comprised 4004 biopsy records of 3874 patients from 28 centres and reported a total number of 710 paediatric RB in patients < 15 years of age (i.e. 17.7 % of all biopsies performed in the Czech Republic), and when patients aged <18 years were included, the number of paediatric biopsies rose to 1073 (26.4 %) in the year 2000 (31) and to 1327 in 2002 (23). Analyses of paediatric RB from this register have been reported (23, 24, 31). This paper analyses data on RB in children collected at the Department of Paediatrics, University Hospital in Hradec Králové, Czech Republic, from January 1, 1997 to December 31, 2008. The primary aim was to evaluate the diagnostic benefit of the procedure, the secondary aim was to assess the safety of RB and prevalence of clinical complications, and the changes in diagnostic distribution and RB indications throughout one decade.

Several epidemiological data concerning RB in children have been published (1-8, 14-16,19-32, 35).In Czech Republic, a central registry incorporating both adults and children has been established in 1993.By the year 2000 it comprised 4004 biopsy records of 3874 patients from 28 centres and reported a total number of 710 paediatric RB in patients < 15 years of age (i.e.17.7 % of all biopsies performed in the Czech Republic), and when patients aged <18 years were included, the number of paediatric biopsies rose to 1073 (26.4 %) in the year 2000 (31) and to 1327 in A total of 177 RB were performed on native kidneys in 174 paediatric patients between January 1, 1997 and December 31, 2008.Three re-biopsies were done for therapeutic/diagnostic reasons at different time points of follow-up.All biopsies were performed at the Department of Paediatrics in Hradec Kralove by a single consultant nephrologist.The patients' mean age at the time of RB was 12.77 ± 4.17 years; range 1 to 19 years; male to female ratio 1.17:1.Isolated haematuria and haematuria with proteinuria were the two most common indications for biopsy.All patients underwent routine pre-biopsy assessment including medical history, physical examination, blood pressure measurement, laboratory exams including blood count and platelet count, coagulation profile, blood group.27 biopsies in 27 patients (15.3 %) in 1997 were performed under X-ray control with the use of intravenous pyelography and implementing Franklin's modification of Vim-Silvermann needle.The remaining 150 biopsies (84.7 %) in 147 patients were performed under ultrasound guidance, utilising single use biopsy guns in 141 biopsies (79.6 %), in particular Speed cut biopsy gun (Gallini) in 1998-2002, and subsequently, from 2003 onwards, Monopty device gun (Bard).TruCut needle was also used in 9 biopsies (5.1 %).The biopsy needle was 7-10 cm in length, the diameter used was 18G (narrow one) in children under 2 years of age and 14G (broader) in older ones.The use of 18G needle required repeated (at least two) punctures to collect adequate amount of kidney tissue.General anaesthesia was a rule in all children under 12 years of age, while local anaesthesia was used in children above this age.However, general anaesthesia was also necessary in 18 patients exceeding 12 years of age.Premedication with diazepam and pethidine hydrochloride or application of midazolame was performed prior to 107 RB (60.5 %; mean age of patients 15.4 ± 1.6 years, range 12-19 years) who underwent the biopsy under local anaesthesia with 1% trimecain, while in 70 RB (39.5 %; mean age of patients 8.6 ± 3.6 years, range 1-16 years), general anaesthesia was necessary.The following data were evaluated: clinical symptoms prior to biopsy, clinical and histological diagnosis; presence of haematuria (microhaematuria or macrohaematuria) before and after biopsy; presence of arterial hypertension defined on the basis of Second Task Force on Blood Pressure Control in Children (34) before and after biopsy or permanent treatment with antihypertensive medication; clinical complications after renal biopsy (with serious complications defined as: arterio-venous fistula, presence of hypovolaemic shock and need for blood transfusion).All biopsies were performed on an in-patient basis, close post-biopsy monitoring involved blood pressure control, blood count, urine assessment and renal ultrasonography 24 hours after the RB.Histological evaluation by light microscopy and immunofluorescence was performed routinely, combined with electron microscopy in all cases.Histological classification of renal diseases used the WHO recommendations

Results
The largest amount of biopsies was performed in children aged 12-17 years (Fig. 1) especially in 1997-1998, while a decline in the number of achieved biopsies has been observed since the year 2002 (Fig. 2).The mean annual number of biopsies performed in 1997-2001 was significantly higher than in the 2002-2008 period (21.6 ± 5.5 versus 9.9 ± 1.2; p = 0.0003).
Haematuria was found in 151 children (86.8 %) prior to RB; this consisted of microscopic haematuria in 98 cases (56.3 %) and macroscopic haematuria in 53 (30.5 %).Proteinuria was present in 81 children (46.5%) prior to RB, with the following pattern: < 1 g/24 hours once (0.6 %), 1-3 g/24 hours in 50 cases (28.7 %), 3-10 g/24 hours in 22 cases (12.6 %) and above 10g/24 hours in 8 cases (4.6 %).Isolated haematuria was present in 93 patients (53.5 %), this comprised of microscopic haematuria (n= 56; 32.2 %) and macroscopic haematuria (n= 37; 21.3 %); isolated proteinuria was present in 26 patients (14.9 %), while in 55 patients (31.6 %) there was an overlap of both haematuria and proteinuria.The clinical symptoms/indications throughout the years 1997-2008 are presented in Tab. 1, with isolated haematuria being usually the most frequent indication for RB, followed by haematuria with proteinuria.Arterial hypertension and/or permanent treatment with antihypertensive medication was present in 33 children (19.0 %) prior to biopsy; all children with hypertension were adequately treated at the time of RB. 176 bioptic samples (99.4 %) were diagnostic.The mean number of glomeruli obtained was 23.5 ± 11. 4   Accordingly, the patients with IgA nephropathy presented most frequently with macroscopic haematuria, and proteinuria with haematuria, while subjects with mesangioproliferative glomerulonephritis had isolated microscopic haematuria or recurrent macroscopic haematuria, followed by proteinuria with haematuria.Children with TBM presented with isolated microscopic haematuria, while subjects with Alport's syndrome had isolated microscopic or recurrent macroscopic haematuria.Patients with MCD presented with isolated proteinuria and proteinuria with haematuria (Tab.4).
Concerning the indications for RB, there was an apparent drop in the percentage of patients with macroscopic haematuria since 2006 and with isolated microscopic haematuria in the years 2006 and 2008, respectively.Furthermore, there was a rising tendency in the percentage of biopsied patients indicated for proteinuria with haematuria since 2004 and a similar trend in the amount of subjects with isolated proteinuria since 2004, with the exception of years 2005 and 2007, respectively (Tab.The changes in percentage of remaining histological diagnoses are difficult to assess and interpret due to low patient numbers.Similarly, the 2006 results are difficult to assess and interpret due to low number of RB performed that year. Regarding the age, the patients with MCD and IgM nephropathy were significantly younger at the time of renal biopsy when compared to all other diagnoses (p = 0.0001), with the exception of Henoch-Schoenlein purpura patients, who were also significantly younger than the children with IgA nephropathy, TBM and Alport's syndrone (p = 0.04 and p = 0.01), respectively.Otherwise, there were no significant age-dependent differences among the various groups sorted by respective diagnoses.
No major complications were encountered and only minor complications occurred in 43 cases (24.2 %), not requiring medical intervention.The most common complication was asymptomatic perirenal haematoma detected by ultrasound 2-3 days after renal biopsy (n=33; 18.6 %).Macroscopic hematuria on day 1-3 post biopsy was present in 8 children (4.5 %).Perirenal hematoma accompanied by abdominal pain occurred in 2 patients (1.1 %).Blood transfusion was never necessary.

Discussion
This report provides information about the occurrence of renal diseases diagnosed by renal biopsy at a single centre during a period of 12 years covering the population of a region with 207,385 children and adolescents.Male predominance in biopsy-proven kidney diseases corresponds with the data published by other authors (1,6,8,10,25,30,31).The patients' mean age of 12.77 ± 4.17 years at the time of RB is very similar to most other observations, where the mean age ranged from 9 to13 years (1,7,12,15,20,23,30,35).The significantly lower age of patients with MCD and IgM nephropathy was related to the onset of NS, in particular steroid-dependent nephrotic syndrome.
According to the Czech registry, the number of RB in children aged < 15 years in the Czech republic before the year 2000 was high (17.7 % of all biopsies) when compared to results from other countries (5.7 % in Italy in 1992-94, 7.0 % in Spain between 1994-99, 5.2 % in Australia 1995-97) (8,12,30), apparently indicating more liberal criteria for RB among Czech paediatric nephrologists at that time (31).However, higher proportions of paediatric biopsies have also been reported in Asia, with 40.5 % out of all renal biopsies, in Korea (10) and in Japan with 20 % (22,31).Our results indicate that the number of RB at our site has decreased significantly after the year 2001.The reason why number of performed RB has declined in recent years, could be attributed to the generally acknowledged fact that RB is often not performed when the likelihood of a therapeutic consequence is low (e.g.steroid-sensitive and steroiddependent nephrotic syndrome, microscopic hematuria, intermittent isolated haematuria, post-infection glomerulonephritis).At our site there was a significant drop in the number of RB, mostly due to retraction of biopsies in patients with isolated haematuria.
Therefore, the reason why the spectrum of histological diagnoses in Czech Republic differs from reports from other countries is most probably due to more liberal approach to RB in the earlier years (1997)(1998)(1999)(2000)(2001).As isolated haematuria was the most frequent indication for RB, there was, consequently, a high number of histologicaly confirmed IgA nephropathies.This is also reflected by the fact that the drop in number of RB in patients with isolated haematuria at our site was followed by a decrease in number and percentage of IgA nephropathies and an increase in TBM.
1).With regard to histologic diagnosis, there was a drop in percentage of IgA nephritis since 2005, with the exception in 2006, and in mesangioproliferative glomerulonephritis since 2003, except for the year 2006.We observed an increase in percentage of TBM since 2003, with the exception of years 2006 and 2008, respectively (Tabs.3a,b).
(range 4-55) per sample.The RB resulted in information yielding a definite diagnosis and/or prognosis in 173 children (99.4 %), however this did not always result in a substantial change in therapeutic strategy.The most frequent diagnosis was IgA nephropathy, followed by mesangioproliferative glomerulonephritis, thin basement membrane glomerulopathy (TBM), Alport's syndrome and minimal change disease (MCD) (Tab.2).The three rebiopsies were performed in patients with Wegener's granulomatosis, lupus nephritis and IgA nephropathy, respectively.The annual numbers and percentage of each group of nephropathies are presented in Tabs.3a, b.Clinical symptoms with respective diagnostic distribution are presented in Tab. 4. The most frequent diagnoses in patients with isolated microscopic haematuria were: TBM, mesangioproliferative glomerulonephritis and Alport's syndrome; in patients with recurrent macroscopic haematuria: IgA nephropathy, mesangioproliferative glomerulonephritis and Alport's syndrome; in children with isolated proteinuria: MCD, IgM nephropathy and Henoch-Schoenlein purpura; in subjects with both proteinuria and haematuria: IgA nephropathy, Henoch-Schoenlein purpura, mesangioproliferative glomerulonephritis and lupus nephritis, respectively (Tab.4).
Clinical symptoms and diagnostic distribution.Number of patients and percentage (in parenthesis).