Background: The aim of the study was to assess idiopathic nephrotic syndrome (INS) relapse rate, co-morbidities, and social status of adults diagnosed with INS in childhood.

Material and methods: A written questionnaire was sent to 118 adults treated for INS in childhood. In 61 (51.7%) responders (aged 26.0 ± 6.2 years, range 18 - 51.5 years), we used available medical records to evaluate age at the onset of INS, number of INS relapses below 18 years of age, response to corticosteroids (CS), renal biopsy findings, and immunosuppressive treatment as well as questionnaire to evaluate the number and treatment of INS relapses above 18 years of age, co-morbidities, age at menarche, marital status, offspring, educational status, and occupation.

Results: In the group of 61 responders, median age at the onset of INS was 3 (range 1.3 - 14.0) years, median number of INS relapses at < 18 years of age was 5 (1 - 20). Steroid-sensitive nephrotic syndrome (SSNS) was diagnosed in 37 (60.7%) patients, steroid-dependent nephrotic syndrome SDNS in 18 (29.5%) patients, and steroid-resistant nephrotic syndrome (SRNS) in 6 (9.8%) patients. Mesangial proliferation was the most common pattern in renal biopsy (35.7%). All patients received CS, 15 were treated with methylprednisolone pulses, 13 with cyclophosphamide, 11 with chlorambucil, 2 with cyclosporine, and 21 with levamisole. All patients achieved remission and had normal renal function at the age of 18. In adulthood, INS relapsed in 10 (16.4%) patients, including 5 (13.5%) patients with SSNS, 4 (22.2%) with SDNS, and 1 (16.7%) with SRNS (p = 0.72). Median number of relapses was 2 (range 1 - 11). Patients with relapses at > 18 years of age had more (p < 0.005) relapses at < 18 years of age. Hypertension was diagnosed in 8 (16.1%), overweight in 14 (23.0%), obesity in 3 (4.9%), and bone fractures in 12 (19.7%) patients. Five patients had height < 3rd percentile, including 4 with INS onset at < 3 years of age. One patient had growth retardation before the treatment. No myocardial infarctions, strokes, severe infections, or malignancies were reported. Mean age at menarche was 12.9 ± 1.4 years, 37 (60.7%) patients were in a steady relationship/ married, 1/18 (5.6%) patients treated with cytostatic agents and 12/43 (24/7%) patients not treated with cytostatic agents had offspring (p < 0.05). Elementary education was reported by 4 (6.6%), secondary education by 32 (52.5%), and higher education by 25 (40.9%) patients, and 34 (55.7%) patients were professionally active. None of the 6 patients with SRNS developed end-stage renal disease.

Conclusions: 1. High number of INS relapses in childhood is a risk factor for recurrences in adulthood. 2. INS relapses in childhood do not preclude active professional life in adulthood.