Medicine
A 30-year-old man presents to the clinic with lower limb edema and fatigue for 1 month.
Examination reveals pitting edema over both legs up to the knees. His systemic examinations are unremarkable (see lab results). Which of the following is the most appropriate diagnosis?
Explanation
Core Concept: Acute Glomerulonephritis (GN) is an inflammatory condition of the glomeruli that impairs filtration, leading to nephritic syndrome (edema, hypertension, hematuria, and oliguria).
Clinical Presentation:
- Periorbital and lower extremity pitting edema, fatigue, hypertension, and dark 'cola-colored' urine.
- Complications: Acute kidney injury, hypertensive encephalopathy, and progression to chronic kidney disease.
Diagnosis:
- First-line: Urinalysis showing dysmorphic red blood cells, RBC casts, and sub-nephrotic proteinuria. Serum creatinine, complement levels (C3/C4), and autoimmune serology (ANA, ANCA, anti-GBM).
- Gold Standard: Percutaneous kidney biopsy to determine the specific histological pattern (e.g., post-infectious GN, IgA nephropathy, lupus nephritis) and guide immunosuppressive therapy.
Management:
- Acute management: Strict blood pressure control, loop diuretics for volume overload/edema, and treating the underlying cause (e.g., antibiotics for post-streptococcal GN).
- Long-term/definitive: Immunosuppression (corticosteroids, cyclophosphamide, rituximab) for autoimmune or rapidly progressive GN. ACE inhibitors or ARBs to reduce proteinuria and slow CKD progression.