Chapter 30 Glomerulonephritis
PATHOPHYSIOLOGY
Glomerulonephritis is a term used for a collection of disorders that involve the renal glomeruli, which are responsible for filtering body fluids and wastes. Two types of this disease are seen, acute and chronic, with chronic being the progressive form. Acute glomerulonephritis is the most common form of nephritis in children. It is an inflammation of the glomeruli that usually follows a streptococcal upper respiratory tract infection. It is considered an immune-complex disease. The glomerular injury is induced by antigen-antibody complexes trapped in the glomerular filter. The glomeruli become edematous and are infiltrated with polymorphonuclear leukocytes, which occlude the capillary lumen. This condition results in decreased plasma filtration, causing excessive accumulation of water and retention of sodium. The resultant plasma and interstitial fluid volumes lead to circulatory congestion and edema. Hypertension is associated with glomerulonephritis.
INCIDENCE
1. Glomerulonephritis is most common in school-aged children.
2. Ages of peak incidence are from 2 to 6 years.
3. The disorder occurs predominantly in boys in childhood; in adolescence, no male or female predilection is seen.
4. Of children with acute glomerulonephritis, 60% to 80% have a history of a preceding upper respiratory tract infection or otitis media (typically, the child was in good health before the infection).
CLINICAL MANIFESTATIONS
1. Nephritis tends to have an average latency period of approximately 10 days, with onset of symptoms 10 days after the initial infection.
2. Initial signs are puffiness of the face, periorbital edema, anorexia, and dark urine.
3. Edema tends to be more prominent in the face in the morning; then it spreads to the abdomen and the extremities during the day (moderate edema may not be recognized by someone who is unfamiliar with the child).
4. Urinary output is decreased.
5. Urine is cloudy or smoky, or described as having the color of tea or cola.
6. The child is pale, irritable, and lethargic.
7. Younger children may appear ill but seldom express specific complaints.
8. Older children may complain of headaches, abdominal discomfort, vomiting, and dysuria.
