Background. In minimal change nephrotic syndrome (MNCS), the most common primary nephrotic syndrome in children, ∼95% of cases show excellent responses to steroid therapy. However, responding patients may become steroid dependent and experience serious side effects. Although oral cyclophosphamide has been recommended in these patients, long-term side effects such as gonadal toxicity are an important concern. Therefore, cyclophosphamide pulses given intravenously may provide an option that maintains remission with less-frequent side effects.

Methods. We treated 20 primary steroid-dependent MCNS patients (15 boys and five girls) with intravenous cyclophosphamide. The patients were children with ages ranging from 3 to 15 years of age. Remission was induced by steroids followed by cyclophosphamide at a dose of 500 mg/m² body surface area per month for 6 months. During this period, we attempted to completely withdraw steroids and maintain patients on cyclophosphamide alone. We monitored the patients for the occurrence of relapse and side effects during this period and for an additional 6 months after withdrawal of cyclophosphamide.

Results. At the end of the 6-month cyclophosphamide treatment period (i.e. 4 months after steroid discontinuation), nine patients (45%) were in remission on cyclophosphamide alone. However, patients that maintained treatment-free remission (cyclophosphamide responders) decreased to five (25%), two (10%) and one (5%) at 6 months, 1 year and 2 years, respectively.

Conclusion. We found that a 6-month course of pulse cyclophosphamide produced unfavourable effects in the majority of paediatric patients with steroid-dependent nephrotic syndrome.