Food allergy as a cause of nephrotic syndrome

Townsend Letter for Doctors and Patients, Oct, 2005 by Alan R. Gaby

Six children (aged 10-13 years) with steroid-responsive idiopathic nephrotic syndrome were studied. Prednisone was discontinued and a hypoallergenic elemental diet was given. After proteinuria had decreased to 500 mg per 24 hours or less on consecutive days (usually within 3-10 days), patients were challenged with cow's milk. Cow's milk challenge resulted in the return of significant proteinuria, edema, and decreased urine volume, together with a decrease in serum IgG concentrations in four patients. An acute alteration of plasma C3 complement component accompanied milk challenge in all six patients. Intradermal skin testing with cow's milk extract was positive in all six patients.

Comment: These results suggest that food allergy, particularly allergy to cow's milk, plays a role in the pathogenesis of idiopathic steroid-responsive nephrotic syndrome. Although the sample size was small, other studies have confirmed that food allergy is a factor in at least some cases of nephrotic syndrome. An elimination diet, followed by individual food challenges, can often be used to identify foods to which a person is sensitive. In patients with nephrotic syndrome, serial urinary protein measurements can help determine whether the diet is effective and what the offending foods are. Patients who are able to control their nephrotic syndrome with dietary modification alone will be spared the adverse effects of long-term prednisone use.

Sandberg DH, et al. Severe steroid-responsive nephrosis associated with hypersensitivity. Lancet 1977;1:388-391.