Differential Diagnosis for Severe Nephrotic Syndrome in an 84-Year-Old Male with CKD Stage 3

Single Most Likely Diagnosis

• Focal Segmental Glomerulosclerosis (FSGS): This is a common cause of nephrotic syndrome in adults, especially in those with a background of chronic kidney disease (CKD). The age and CKD stage 3 of the patient increase the likelihood of FSGS.

Other Likely Diagnoses

• Membranous Nephropathy: This is another common cause of nephrotic syndrome in adults. It can be primary (idiopathic) or secondary to other conditions such as autoimmune diseases, infections, or drugs.
• Minimal Change Disease: Although more common in children, minimal change disease can occur in adults and is a significant cause of nephrotic syndrome. It is characterized by the loss of foot processes of podocytes as seen on electron microscopy.
• Amyloidosis: This condition involves the deposition of amyloid fibrils in various tissues, including the kidneys, leading to nephrotic syndrome. The patient's age and lack of diabetes make this a plausible diagnosis.

Do Not Miss Diagnoses

• Multiple Myeloma: This is a plasma cell dyscrasia that can cause nephrotic syndrome through various mechanisms, including light chain deposition disease. Given the patient's age, multiple myeloma is a critical diagnosis not to miss due to its significant implications for treatment and prognosis.
• Vasculitis (e.g., ANCA-associated vasculitis): Although less common, vasculitis can cause nephrotic syndrome and rapidly progressive glomerulonephritis. Missing this diagnosis could lead to delayed treatment and poor outcomes.
• Lupus Nephritis: Systemic lupus erythematosus (SLE) can cause nephrotic syndrome. Although SLE is more common in younger females, it can occur in older adults, and its diagnosis is crucial due to the need for specific treatment.

Rare Diagnoses

• Lymphoma: Certain types of lymphoma can cause nephrotic syndrome, either directly by renal infiltration or indirectly through the production of nephrotic factors.
• Monoclonal Immunoglobulin Deposition Disease: This rare condition involves the deposition of monoclonal immunoglobulins in the kidney, leading to nephrotic syndrome.
• Fabry Disease: A genetic disorder that can lead to nephrotic syndrome due to the accumulation of globotriaosylceramide in various tissues, including the kidneys. It is rare but important to consider in patients with unexplained nephrotic syndrome and systemic symptoms.