[Mycophenolate mofetil (MMF) as the first choice immunosuppressive drug in treatment of steroid-dependent nephrotic syndrome in children]

Most children diagnosed with nephrotic syndrome show favourable response to corticosteroid therapy, nonetheless 30% of patients have frequent relapses or a steroid-dependent course of disease. Cyclophosphamide, cyclosporin A or MMF are being used in treatment of steroid-dependent nephrotic syndrome in search of a drug with highest long-term effectiveness and least amount of side effects.

AIM

The aim of study was to assess of the efficacy of MMF as the first choice immunosuppressive drug in children with nephrotic syndrome after determining a steroid-dependency.

MATERIALS AND METHODS

23 children with steroid-dependent nephrotic syndrome were enrolled in the study. Mean age at disease onset was 3.8 years. Mean disease duration time before introducing MMF was 21.3 months. Mean treatment time with MMF was 23.6 months. Patients previously treated with immunosuppressive drug, except for prednisone were excluded from the study.

RESULTS

Per year of treatment with MMF 56,5% of patients had not more than 1 relapse of the disease, 5 patients had more than 1, but less than 2 relapses. After the mean time of 23.6 months MMF treatment was discontinued in 15 patients (62,5%). 11 patients (48%) from that group significantly benefited from treatment in the form of no further relapses, defer of steroid-dependence or the possibility to reduce the dose of corticosteroids to minimal.

CONCLUSIONS

MMF has advantage over cyclophosphamide and calcineurin inhibitors in reference to side effect profile, especially glomerular filtration markers, hypertension and frequent drug dependency. Treatment with MMF is effective in maintaining long-term remission and enables the reduction of cumulative steroid dose. Regarding nearly 50% of patients with benefits after MMF treatment and good treatment tolerance, it seems justified to introduce MMF as the first choice immunosuppressive drug in patients with steroiddependent nephrotic syndrome.

Modification of the Schwartz equations for children increases their accuracy at eGFR > 60 mL/min/1.73 m(2)

AIM

Estimation of eGFR in children with normal kidney function using the Schwartz equations results in underestimating real GFR.

MATERIALS AND METHODS

We propose modification of three Schwartz equations - two based on creatinine concentration (eGFRScrBS bedside) and (eGFRScr) and one 3-marker based on creatinine, urea and cystatin C concentrations (eGFRS3M). The iohexol test (reference method) was performed 417 times in 353 children >2 years with mean GFR: 98 ± 31.6 ml/min/1.73m(2). The assessment included also the Filler and Zappitelli equations. The modification was performed using methods: (1) based on equation, eGFRcor = a [eGFR - T] + T, where T = 50, if eGFR > T, and a equals for: eGFRScrBS 1.4043, for eGFRScr 2.0048, for eGFRS3M 1.2951, and (2) based on correction of all coefficients of the original equation.

RESULTS

For comparison of all the results and for children with GFR< 60, 60-90, 90-135 and > 135 ml/min/1.73m(2) the correlation coefficient, relative error (RE) and root mean square relative error (RMSRE) was employed and revealed improvement of RE from 25.9 to 6.8 and 3.9% (depending on the correction method) for eGFRScr; from 19 to 8.1 and 3.9% for eGFRScrBS and: from 11.6% to 2.0 and 2.3% for eGFRS3M (respectively). The RMSRE values changed from 30 to 21.3 and 19.8% for eGFRScr, from 25.1 to 21.6 and 19.8% for eGFRScrBS and from 19.1 to 15.8 and 15.3 % for eGFRS3M.

CONCLUSIONS

Modifications of Schwartz equations at GFR > 60 ml/min/1.73m(2) significantly improves the accuracy of calculating eGFR. The 3-markers equation is more accurate and should be employed frequently.

Which equations should and which should not be employed in calculating eGFR in children?

PURPOSE

We assessed the reliability of calculating eGFR in children as compared to the iohexol disappearance test (GFR-I), which was performed 417 times in 353 children aged 2 and more.

MATERIAL/METHODS

eGFR was estimated with equations based on serum creatinine: Schwartz (1: eGFR-Scr), Cockroft-Gault (2: eGFR-CG) and MDRD (3: eGFR-MDRD), and on creatinine clearance (4: eGFR-U), or relying on serum cystatin C: Hoeck (5: eGFR-H), Bokenkamp (6: eGFR-B) and Filler (7: eGFR-F), and on the three Schwartz markers (8: eGFR-S3M). Mean relative error (RE), correlation (R), Bland-Altman analysis and accuracy of GFR-I were studied in all patients and in subgroups: at GFR<60ml/min/1.73m(2); in children aged ≤12 and >12.

RESULTS

The results by eGFR-Scr, eGFR-S3M demonstrated no statistical difference to GFR-I at GFR<60ml/min/1.73m(2), but underestimated eGFR at higher filtration values by 11.6±15.1% and 19.1±16.4, respectively (p<0.0000). The eGFR-B, eGFR-F and eGFR-MDRD equations illustrated important overestimation of reference GFR results (RE: 84±44.2%; 29.5±27.9%, 35.6±62%; p<0.0000 for all). The MDRD and C-G formulas showed statistically better consistency in children aged >12. A good agreement was achieved by the eGFR-H equation (5.1±21.9%; p<0.0000; R=0.78).

CONCLUSIONS

(1) Schwartz equations show a good conformity at GFR<60ml/min/1.73m(2), but underestimate the results at higher GFR values. (2) The Bokenkamp equation with original coefficient should not be employed in children. (3) The use of the Hoeck formula in all children and C-G and MDRD formula in children aged >12 is possible. (4) The error of eGFR calculations increases at higher GFR values.

[Mycophenolate mofetil in treatment of childhood nephrotic syndrome--preliminary report]

The management of nephrotic syndrome (NS) in children remains a clinical challenge for pediatricians and pediatric nephrologists. Especially, the treatment of patients with steroid-resistant (SR) and steroid-dependent (SD) nephrotic syndrome, because they are at risk for developing complications from prolonged exposure to steroids, CsA and alkylating agents. Mycophenolate mofetil (MMF) is a selective and reversible inhibitor of inosine monophosphate dehydrogenase used above all in transplantology and recently also in patients with nephrotic syndrome. The aim of this study was to tentatively assess the usefulness and the safety of MMF as an immunosuppressive agent in children with steroid-resistant NS, in whom remission was not obtained with previous treatment regimens, and those with steroid-dependent NS, in whom severe adverse reactions were observed in steroid and cyclosporine therapy. The study included 19 children with NS (11 girls, 8 boys) aged 7 to 19.5 years (a mean of 13.5), treated at the Deptartment of Pediatric Nephrology. The duration of disease was from 1 to 16 years (a mean of 9.3). The patients were divided into 3 groups: I--9 children with steroid-dependent NS; II--6 children with steroid-dependent NS and episodes of steroid-resistance; III--4 children with steroid-resistant NS. All patients in groups II and III required multi-drug therapy (prednisone, cyclosporine A, methylprednisolone, chlorambucil, cyclophosphamide) before MMF was introduced. MMF was administered orally: 180-600 mg/m2 body surface/dose, twice daily. The follow-up period lasted for 4 to 16 months (a mean of 7.7). The clinical outcome analysis included decrease or disappearance of proteinuria, clinical improvement and/or possibility of tapering therapy intensity, especially the dosage of steroids and/or CsA. Also, renal function was monitored with serum cystatine C concentration. Particular attention was paid to adverse effects of MMF upon the gastro- intestinal tract and/or opportunistic infections. All medication (apart from MMF) could be discontinued in 4 patients; in 15 cases, prednizone dose was reduced and in 9 cases CsA dose was reduced or discontinued. In group I (SD) steroid treatment could be reduced from a mean prednisone dose of 22.8 to 3.6 mg/m2/48 hours (p=0.018), in groups II and III, in spite of 50 % reduction of a mean prednisone dose, the difference did not reach statistical significance. During MMF therapy Csa treatment could be reduced from a mean CsA dose 4.3 to 2.9 mg/kg/24 hours (p=0.008). Improvement or preservation of stable renal function was observed in all patients--cystatin C levels decreased significantly from a mean 1.35 to 0.96 mg/l (p=0.007). Adverse reaction to MMF (abdominal pain) was observed in 2 patients (nausea, vomiting, diarrhoea in 1, CMV infection in 1). The initial clinical observation of MMF treatment in nephrotic patients shows its best effect in the group of patients with steroid-dependent NS. MMF can safely be used in children with NS. The introduction of MMF allows for reduction of other chronically used medications, especially CsA and steroids.

[Doppler ultrasound as the main diagnostic procedure in renovascular hypertension]

Renovascular hypertension (RVH) accounts for 5-25% cases of secondary hypertension in children. It is the second most frequent cause of hypertension (second only to aortic coarctation), potentially treatable, provided that early diagnosis is made and no permanent organic lesions develop. No clinical symptoms are observed in more than 60% children with renovascular hypertension; hypertension itself is diagnosed incidentally, in routine checkups. The patient is often hospitalised only after organic complications. The study aim was to verify the value of Doppler examination in the diagnosis of renovascular hypertension in children. In 2001, four out of 18 patients of the Nephrology Department examined due to hypertension were diagnosed with renovascular hypertension. In three of them, examination demonstrated aneurysmatic widening of renal artery with multiple stenoses, renal artery trunk stenosis, significant stenosis in abdominal aorta and in both renal arteries. In another case, stenosis of an additional renal artery was observed. All diagnoses were made with Doppler ultrasound and confirmed by angiography. Colour and spectral Doppler ultrasound examination is a non-invasive and valuable method of diagnosing hypertension in children.

[Results of treatment of lupus nephritis in children. Own experience]

The study aims at assessing the results of treating lupus nephritis in 31 children, aged 4-16 years at the diagnosis of the disease. Renal biopsy was performed in 29 patients. Patients were divided into 2 groups. Group 1 included 15 children treated in 1980-92 and group 2 included 16 children treated in 1993-98. The average age, sex and follow-up were similar in both groups. All children were treated with corticosteroids. Alkylating agents were administered to 12 patients in group 1 and in 14 in group 2. Group 2 patients were given cyclophosphamide in monthly intravenous pulses, and methylprednisolone according to the Mendoza regime. In Group 1, 8 remissions (53%) were observed. Better results with more aggressive treatment were obtained in group 2--13 remissions (81%).