Nephrotic Syndrome:
Define:
– Proteinuria (>3.5 g/24h or urine/creatinine > 3.5 mg/mg)
– Hypoalbuminemia
– Clinical evidence of edema
* Other clinical manifestations (hyperlipidemia, coagulation abnormalities) are related to losses of proteins other than albumin or caused by increased protein synthesis.

Nephrotic Range Proteinuria: > 3 g/24h without other findings

Nephritic Syndrome:
Characterized by: proteinuria, hematuria, pyuria, and often decreased kidney function and hypertension
– due to injury or inflammation within the glomerulus that allows the passage of protein, erythrocytes, and leukocytes into the renal tubule.
– resulting damage can lead to decreased GFR, kidney function, and abnormal blood pressure

IgA Nephropathy:
– most common primary glomerulonephritis
– an immune complex disease in which IgA antigen-antibody complexes are depositied primarily in the mesangium
– may be primarily involve the kidney or may be secondarily associated with other conditions

Epidemiology: occurs at any age, but usually found in men (20-30 yo) who are white or Asian
– develops to ESRD in approximately 20-30% of patients within 10-20 years of onset

Risk factors for progression: younger age at onset, hypertension, proteinuria > 1 g/24h, elevated creatinine, and low GFR

Clinical manifestations:
– typically asymptomatic at presentation with only microscopic hematuria and proteinuria on urine evaluation
– common presentation: recurrent gross hematuria occuring synchronously with an episode of respiratory or GI infection

Diagnosis: confirmed by kidney biopsy

Management: ACE inhibitors or ARBs, with goal urine protein excretion < 1 g/24h

Simplified Approach to GN:
Step 1: determine the broad cause of the acute or progressive renal failure
– Pre-renal, intrinsic renal, or post-renal
– FENa (if oliguric to differentiate pre-renal from ATN), UA (evaluated for sediment), and renal US (rule out obstruction)
– If INTRINSIC renal than the differential is either: Glomeruli, Tubules, Interstitum, Vessels

Step 2: If a glomerular cause – differentiate between GLOMERULONEPHRITIS pattern from a NEPHROTIC SYNDROME pattern
– UA, renal US, 24 hour urine protein (urine protein:creatinine ratio)
– Look for active sediment (UA with protein and RBCs, dysmorphic RBCs, and/or RBC casts)


Step 3: Use the serum complement levels to differentiate cause of GN
Low Complement GN:
Systemic: SLE, endocarditis, cyroglobulinemia
Isolated Renal: post-infectious GN, MPGN

Normal Complement GN:
Systemic: HSP, ANCA-associated, Goodpasture’s syndrome, hypersensitivity vasculitis
Isolated Renal: IgA nephropathy, anti-GBM disease, RPGN