Differential Diagnosis
The patient presents with a history of upper respiratory infection, followed by periorbital edema, significant proteinuria (3+), and hematuria (5+ RBCs). These symptoms suggest a renal involvement, possibly secondary to an immune-mediated process. Here's a categorized differential diagnosis:
Single Most Likely Diagnosis
- Post-Streptococcal Glomerulonephritis (PSGN): This condition is a leading cause of acute nephritic syndrome, especially after a streptococcal infection like pharyngitis or impetigo. The latency period between the infection and the onset of renal symptoms, the presence of hematuria, and proteinuria support this diagnosis. Histologically, PSGN is characterized by diffuse proliferative glomerulonephritis.
Other Likely Diagnoses
- IgA Nephropathy (Berger's Disease): This is another common cause of nephritic syndrome and can be triggered by infections. It presents with hematuria, often following an upper respiratory tract infection. Histology shows mesangial IgA deposits.
- Alport Syndrome: Although less common, Alport syndrome can present with hematuria and proteinuria, especially in males. However, it typically has a familial component and is associated with sensorineural hearing loss and eye abnormalities. Histology may show thinning and thickening of the glomerular basement membrane.
Do Not Miss Diagnoses
- Rapidly Progressive Glomerulonephritis (RPGN): This is a clinical syndrome characterized by a rapid decline in renal function, often with severe oliguria and signs of nephritic syndrome. It can be caused by various diseases, including anti-GBM disease, vasculitis, or severe forms of glomerulonephritis. Missing this diagnosis could lead to irreversible renal failure.
- Vasculitis (e.g., ANCA-associated vasculitis): Conditions like Granulomatosis with Polyangiitis (GPA) or Microscopic Polyangiitis (MPA) can present with renal involvement, including nephritic syndrome, and require prompt treatment to prevent organ damage.
Rare Diagnoses
- Membranoproliferative Glomerulonephritis (MPGN): This is a less common cause of nephritic syndrome, characterized by changes in the glomeruli that lead to their proliferation and the deposition of material in the glomerular basement membrane. It can be associated with infections, autoimmune diseases, or complement pathway abnormalities.
- Lupus Nephritis: Although systemic lupus erythematosus (SLE) can cause a wide range of renal manifestations, including nephritic syndrome, it is less likely given the lack of other systemic symptoms or a known history of SLE. Histology can vary widely depending on the class of lupus nephritis.
Each of these diagnoses has distinct histological features that can guide the diagnosis upon renal biopsy. The clinical context, including the history of recent infection and the specific combination of urinary findings, helps narrow down the differential diagnosis.