reported the results of a long term follow up in an unselected childhood population with Henoch-Sch6nlein purpnra (HSP). In this follow up the authors excluded "patients with no clinical evidence of renal disease during the acute illness". We think that this exclusion may lead to an understimation of the actual incidence of nephropathy in HSP. In fact, according to Hurley and Drummond [3], renal involvement in HSP patients can occur also 4-8 weeks after the presentation of the acute disease, when patients are clinically recovered. Counahan et al.
[2] reported nephropathy in three patients who were normal at 2-year follow up. Meadow [4] showed focal proliferative nephritis with renal insufficiency in a child without urinary and/or clinical signs of renal involvement in the acute phase of the disease.
In our experience, HSP nephropathy can occur several months after recovery from the skin lesions. Starting from 1978 and up to December 1986 we have studied 168 HSP patients who have been followed up for more than 18 months after the initial presentation of the rash. All patients had characteristic skin lesions and joint pain, and 50 of them also abdominal pain. Occult blood was present in the stools of 46 patients. Nephropathy, characterized by haematuria (more than 10 erythrocytes/microscopic field at 400 • and/or proteinuria (more than 500mg/1), hypertension (blood pressure >2SD above the normal), azotaemia (> mg 54/dl), serum creatinine (> mg 1.20/dl) was present at initial presentation in 34 patients (20.2%). In two additional patients microscopic haematuria and proteinuria without hypertension and hyperazotaemia appeared after 6 and 15 months, respectively.
For these reasons, in spite of conflicting opinions [1, 5], we think that all HSP patients should be followed up for at least 3 years before nephropathy can be excluded, and that the figures given by Stewart et al. [5] of < 1% mortality and of 1.1% morbidity for HSP nephropathy can be applied only to early onset nephropathy, because the cases in which renal involvement appears later may have a different prognosis.