Differential Diagnosis for Arthalgias, Proteinuria, and Red Blood Cell Casts
- Single Most Likely Diagnosis
- Systemic Lupus Erythematosus (SLE): This autoimmune disease is known to cause arthalgias, proteinuria, and red blood cell casts due to its effects on multiple organ systems, including the kidneys and joints.
- Other Likely Diagnoses
- IgA Nephropathy: A common cause of kidney disease that can present with hematuria (indicated by red blood cell casts) and proteinuria, and may be associated with arthalgias.
- Post-Streptococcal Glomerulonephritis (PSGN): An immune complex-mediated disease that can occur after streptococcal infections, leading to kidney inflammation, which may cause proteinuria, hematuria, and potentially arthalgias.
- Rheumatoid Arthritis (RA) with secondary kidney involvement: While RA primarily affects the joints, it can also have systemic manifestations, including kidney disease, which might present with proteinuria and hematuria.
- Do Not Miss Diagnoses
- Vasculitis (e.g., ANCA-associated vasculitis): These conditions can cause kidney damage leading to proteinuria and red blood cell casts, and also affect the joints, causing arthalgias. Missing these diagnoses could lead to severe organ damage.
- Goodpasture Syndrome: An autoimmune disease that affects the kidneys and lungs, characterized by the presence of anti-GBM antibodies. It can present with hematuria, proteinuria, and renal failure, along with arthalgias.
- Rare Diagnoses
- Alport Syndrome: A genetic disorder affecting the type IV collagen in the kidneys, ears, and eyes. It can lead to kidney disease with hematuria and proteinuria but is less commonly associated with arthalgias.
- Membranoproliferative Glomerulonephritis: A type of glomerulonephritis that can cause proteinuria and hematuria, and while it's less commonly associated with arthalgias, it's a consideration in the differential diagnosis due to its potential for systemic symptoms.