Overview
Definition
A clinical syndrome caused by severe glomerular capillary wall damage leading to massive urinary protein loss.
Epidemiology
Can occur at any age. Minimal Change Disease is most common in children; Focal Segmental Glomerulosclerosis (FSGS) and Membranous Nephropathy in adults.
Etiology & Risk Factors
- Minimal Change Disease (triggered by infections/NSAIDs)
- Focal Segmental Glomerulosclerosis (FSGS - associated with HIV, Heroin, Obesity)
- Membranous Nephropathy (associated with solid tumors, Hepatitis B, SLE)
- Diabetic Nephropathy (secondary cause)
Clinical Symptoms
- Massive, generalized edema (anasarca), especially periorbital and pitting lower extremity edema
- Frothy urine
- Fatigue
Clinical Approach
Diagnosis
- Heavy Proteinuria: > 3.5 grams per day (or UACR > 3.5)
- Hypoalbuminemia: < 3.0 g/dL (due to protein loss)
- Hyperlipidemia (liver ramps up lipoprotein synthesis in response to low oncotic pressure)
- Urine Microscopy: Oval fat bodies ('Maltese crosses' under polarized light)
- Renal Biopsy (needed in adults to determine specific type)
Management
- Diuretics (Loop diuretics) for edema
- ACE inhibitors / ARBs to reduce proteinuria
- Statins for hyperlipidemia
- Immunosuppression (Corticosteroids are highly effective for Minimal Change Disease)
Complications
- Hypercoagulability and Thrombosis (loss of Antithrombin III in urine, specifically Renal Vein Thrombosis)
- Increased risk of infection (loss of immunoglobulins in urine)