Glomerular diseases present clinically in several different ways depending on the nature and severity of the primary disease and the extent to which the normal physiologic functions of the glomerulus are perturbed. Some children with glomerulopathies are found incidentally to have microscopic hematuria or proteinuria but are otherwise asymptomatic. At the other extreme, children may become critically ill with oligoanuric rapidly progressive glomerulopathy in need of urgent dialysis. Whereas numerous glomerular diseases are inherited (see Chapter 469), most forms are acquired and are generally considered to be immunologically mediated. There are 3 classical clinical syndromes that develop from glomerular injury: acute and chronic glomerulonephritis (GN), defined by the triad of hematuria, hypertension, and acute kidney injury (AKI); nephrotic syndrome (NS), defined by proteinuria and hypoalbuminemia; and hemolytic-uremic syndrome (HUS), defined by microangiopathic hemolytic anemia, thrombocytopenia, and AKI.
The pathophysiologic sequence of events that lead to the development of the nephritic triad (hematuria, hypertension, and AKI) are shown in Figure 468-1. In each of the clinical entities with glomerular proliferation, inflammation leads to decreased glomerular perfusion, resulting in compromised kidney function and retention of salt and water with potential development of hypertension and edema.
Sequence of pathophysiologic events in a patient with acute glomerulonephritis and the associated clinical manifestations. ECF, extracellular fluid; GFR, glomerular filtration rate; RBC, red blood cell; UNa, urine sodium; Uosm, urine osmolality.
APPROACH TO A CHILD WITH GLOMERULONEPHRITIS
The patient with glomerular disease presents clinically with a constellation of features that may include hematuria, proteinuria, edema, hypertension, and AKI. The urinary sediment is characterized as active when dysmorphic erythrocytes and cellular casts are present. A series of questions guides the initial diagnostic and management plan.
Is the process acute or chronic? Many patients with chronic GN appear relatively asymptomatic until the disease is advanced. Clues of chronicity include evidence of chronic kidney disease (CKD): significant anemia, renal osteodystrophy (abnormal bone radiographs or an elevated intact parathyroid hormone level), or small echogenic kidneys on ultrasound examination. Acute onset of severe hypertension often causes neurologic symptoms such as headaches and seizures, whereas long-standing hypertension of insidious onset may be clinically silent, but left ventricular hypertrophy may be present.
Is the kidney disease isolated, or are additional organ systems involved? A careful review of the systems and physical examination will help determine whether the investigation should move in the direction of primary (acquired) GN or toward secondary GN due to multisystem disease (Table 468-1). Relevant extrarenal involvement may be clinically silent. For example, postinfectious serologies (such as a streptozyme or anti–hepatitis B or anti–hepatitis C antibodies) may be indicated if infection-associated GN is a possibility. When patients present with a small-vessel vasculitis, involvement of the lung parenchyma or sinuses ...