Urine Nephrology Now: A Primer for Students in Nephrology
Glomerular diseases represent a diverse group of conditions affecting the glomerular filtration barrier. Understanding the clinical presentations and pathophysiology helps distinguish between different types and guides appropriate treatment.
Characterized by the tetrad of proteinuria (>3.5 g/day), hypoalbuminemia, edema, and hyperlipidemia.
Loss of albumin leads to decreased oncotic pressure and fluid retention. Compensatory liver protein synthesis increases cholesterol production.
Primary: Minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy
Secondary: Diabetes, lupus, amyloidosis, medications
Characterized by hematuria, proteinuria (usually <3.5 g/day), hypertension, and reduced GFR.
Inflammatory process in glomeruli leads to bleeding and reduced filtration.
Most common cause of nephrotic syndrome in children, but can occur in adults. Normal appearing glomeruli on light microscopy, but electron microscopy shows foot process effacement. Highly responsive to corticosteroid therapy with excellent prognosis.
Most common cause of nephrotic syndrome in adults, particularly African Americans. Sclerosis affects only segments of some glomeruli (focal and segmental). More resistant to treatment than minimal change disease and may require immunosuppressive agents.
Common cause of nephrotic syndrome in older adults. Thickening of glomerular basement membrane with subepithelial deposits. Risk stratification determines need for immunosuppressive therapy.
Most common primary glomerulonephritis worldwide. Often presents with episodic hematuria following upper respiratory infections. IgA deposits in the mesangium. Treatment includes ACE inhibitors or ARBs, with immunosuppression reserved for severe cases.
Most common cause of CKD in developed countries. Progresses through stages from hyperfiltration to microalbuminuria, overt proteinuria, and declining GFR. Management includes glycemic control, blood pressure control, ACE inhibitors/ARBs, and SGLT2 inhibitors.
Kidney involvement occurs in 60% of patients with systemic lupus erythematosus. Classified into six classes based on histological findings, with class IV being most severe. Treatment involves immunosuppressive therapy with careful monitoring for complications.
RPGN represents a medical emergency requiring urgent evaluation and treatment. Defined as rapid loss of kidney function over days to weeks, often with crescent formation on biopsy.
Urgent immunosuppressive therapy, often including plasmapheresis for anti-GBM disease.
Focus on family history, medications, systemic symptoms, and signs of systemic disease. Look for rashes, joint pain, or other manifestations of autoimmune disease.
Essential studies include comprehensive metabolic panel, complete blood count, complement levels (C3, C4), autoantibodies (ANA, ANCA, anti-GBM), hepatitis and streptococcal serologies, and serum and urine protein electrophoresis.
Often necessary for definitive diagnosis and treatment planning. Indications include nephrotic syndrome in adults, nephritic syndrome with reduced GFR, AKI of unclear etiology, and CKD with proteinuria and unclear cause.