Mitchell’s parents bring him to the clinic because his urine is tinged with blood. Two days before, he was diagnosed with strep throat. His face and hands are swollen. What is the probable cause of Mitchell’s current kidney problem?
The correct answer and explanation is:
Correct Answer:
Acute Post-Streptococcal Glomerulonephritis (APSGN)
Explanation:
Mitchell’s symptoms—including hematuria (blood in urine), facial and hand swelling (edema), and a recent streptococcal throat infection—strongly suggest Acute Post-Streptococcal Glomerulonephritis (APSGN). This condition is a kidney disorder that occurs after an infection with Streptococcus pyogenes, typically affecting children 1–3 weeks following a strep throat or skin infection.
Pathophysiology:
APSGN is an immune-mediated reaction in which the body’s immune system mistakenly attacks the kidneys. After a streptococcal infection, immune complexes (antigen-antibody reactions) get deposited in the glomeruli—the filtering units of the kidneys. This triggers inflammation, leading to swelling and dysfunction of the kidneys. As a result:
- The glomeruli become more permeable, allowing red blood cells to pass into the urine, causing hematuria (red or cola-colored urine).
- Protein leakage into the urine leads to a reduction in oncotic pressure, causing swelling (edema) in the face and extremities.
- Blood pressure may rise due to fluid retention and impaired kidney function.
Diagnosis & Treatment:
- Urinalysis: Shows hematuria, proteinuria, and red blood cell casts.
- Blood Tests: Reveal elevated anti-streptolysin O (ASO) titers and low complement (C3) levels.
- Treatment: APSGN is usually self-limiting, but supportive care, including blood pressure control, fluid management, and monitoring of kidney function, is crucial. Antibiotics may be given to eradicate any remaining streptococcal bacteria.
Prognosis:
Most children recover fully within weeks, but monitoring is necessary to ensure no long-term kidney damage.