The correct answer is E. This patient has nephrotic syndrome, based on the presence of edema, hypoalbuminemia, hyperlipidemia, and proteinuria >3.5 g. Nephrotic syndrome in children is most often idiopathic and common between ages 1 and 8. Most cases are caused by minimal change disease (Nil disease) in which the renal biopsy specimen reveals few or no changes on light microscopy, but under electron microscopy there is effacement of the renal tubular epithelial foot processes. The urine shows heavy protein (>3.5 g) and no abnormal urinary sediment or hematuria. Children ages 1-8 are likely to have steroid-responsive nephrotic syndrome, and thus initial therapy with prednisone is the most appropriate choice. Parents should also be advised to restrict salt intake until the edema subsides.
Some children with nephrotic syndrome will develop severe edema with ascites or pleural effusions due to massive proteinuria and require hospitalization. When there is risk for respiratory compromise, albumin infusion
(choice A) followed by a potent loop diuretic (such as furosemide, (choice C) may be necessary to mobilize the fluid. In most cases, however, prednisone treatment alone is sufficient to produce resolution of edema.
Cyclophosphamide (choice B) is an immunosuppressive drug that is useful for children who suffer from frequent relapses of nephrotic syndrome despite steroid treatment. It is not used as the primary agent for treatment of nephrotic syndrome.
A high-protein diet (choice D) has no role in managing the hypoalbuminemia seen in nephrotic syndrome caused by continued large losses of albumin in the urine. It is not first-line therapy. These patients are making large amounts of cholesterol to replace the lost protein and these patients are at risk for hyperlipidemia so increasing protein in the diet would only make this problem worse.
PEARL: Nephrotic syndrome is characterized by edema, hypoalbuminemia, proteinuria of >3.5 g, dyslipidemia, and hypercoagulability caused by loss of anti-thrombin III in the urine. Minimal change disease is the most common etiology in children. It is termed such because under light microscopy, the biopsy specimen looks normal, however under electron microscopy, there is effacement of the podocytes (foot processes). Treatment is most commonly steroids, and most children experience a complete remission without recurrence.
