Because greater than 80% of children less than 13 years of age with primary NS have steroid-responsive forms (chiefly MCNS), steroid therapy may be initiated without a renal biopsy if a child has typical features of NS. Typical therapy for MCNS is prednisone, 2 mg/kg/day (60 mg/m2/24 h, maximum 60 mg/day), provided once a day or split into multiple doses. Over 90% of children who respond to steroids do so within 4 weeks. Responders should receive steroids for 12 weeks. A renal biopsy is indicated for nonresponders because steroid resistance decreases the chance that MCNS is the underlying disease. Frequent relapses or steroid resistance may necessitate additional immunosuppressive therapy.
No clearly effective therapy for FSGS has been identified. Approximately 35% respond to steroid therapy; others may respond to immunosuppressive therapy. MPGN and membranous glomerulonephritis may improve with chronic steroid or immunosuppressive therapy but do not reliably remit with standard NS steroid therapy. Aggressive medical therapy of familial congenital NS, with early nephrectomy, dialysis, and transplantation, is the only effective approach to this syndrome.
NS edema is treated by restricting salt intake. Severe edema may require the use of loop diuretics. When these therapies do not alleviate severe edema, cautious parenteral administration of 25% albumin (0.5 to 1.0 g/kg intravenously over 1 to 2 hours) with an intravenous loop diuretic usually results in diuresis. The administered albumin is excreted rapidly, and, thus, salt restriction and diuretics must be continued. Significant pleural effusions may require drainage. Acute HTN is treated with β-blockers or calcium channel blockers. Persistent HTN usually responds to angiotensin-converting enzyme inhibitors.
An increased incidence of serious infections, particularly bacteremia and peritonitis (particularly Streptococcus pneumoniae, Escherichia coli, or Klebsiella), is due to urinary loss of immunoglobulins and complement. Side effects of steroids are most common in steroid-dependent and frequently relapsing patients. Hypovolemia may result from diarrhea or diuretic use. The loss of coagulation factors, antithrombin, and plasminogen may lead to a hypercoagulable state with a risk of thromboembolism (TE). Warfarin, Lovenox, low-dose aspirin, or dipyridamole may minimize the risk of clots in NS patients with a history of TE or high risk for TE. Hyperlipidemia promotes increased atherosclerotic vascular disease.
Most children with NS eventually go into remission. Nearly 80% of children with MCNS experience NS relapse, defined as heavy proteinuria that persists for 3 or more consecutive days. Transient (up to 3 days) proteinuria may occur with intercurrent infection in children with MCNS and is not considered a relapse. Steroid therapy is typically effective for true relapse. Steroid-responsive patients have little risk of chronic renal failure. Patients with FSGS may initially respond to steroids but later develop resistance. Many children with FSGS progress to end-stage kidney failure (see Chapter 165). Recurrence of FSGS occurs in 30% of children who undergo renal transplantation.
A child with gross hematuria may have a serious disease and requires prompt evaluation. Microscopic hematuria, defined as more than 3 to 5 red blood cells (RBCs) per high-power field on freshly voided and centrifuged urine, is often benign. Isolated asymptomatic microscopic hematuria is found in up to 4% of healthy children. In most cases this is a transient finding. Hematuria may originate from glomerular disease, tubulointerstitial processes, and lower urinary tract disorders (Table 163-1).