- A constellation of clinical and laboratory features defined by the presence of massive proteinuria (>3.5 g/1.73 m2/24 hr), hypoalbuminemia (<3 g/dL), severe hyperlipidemia (total cholesterol often >10 mmol/L) (380 mg/dL), and peripheral edema, with risk for thrombotic disease
- It can be due to intrinsic renal disease or secondary to congenital infections, diabetes mellitus, systemic lupus erythematosus, neoplasia, or certain drug use.
- Associated with many types of kidney disease
- Diabetic nephropathy (1)
- Minimal change disease (MCD)
- Most common cause of nephrotic syndrome in children aged <10 years (90%)
- Idiopathic condition in adults associated with NSAID use or Hodgkin lymphoma
- Amyloidosis: 4–17% of idiopathic nephrotic syndrome—two renal types are primary (AL) and secondary (AA)
- Lupus nephropathy (LN): Adult women are affected about 10 times more often than men.
- Focal segmental glomerulosclerosis (FSGS)
- 35% of nephrotic syndrome in adults; most common primary nephrotic syndrome in African Americans
- Has both primary (idiopathic) and secondary forms (associated with HIV, morbid obesity, reflux nephropathy, previous glomerular injury)
- Membranous nephropathy
- Most common cause of primary nephrotic syndrome in adults (40%)
- Most often primary (idiopathic) but can be secondary associated with malignancy, hepatitis B, autoimmune diseases, thyroiditis, and certain drugs including NSAIDs, penicillamine, gold, and captopril
- Membranoproliferative glomerulonephritis (MGN)
- May present in the setting of a systemic viral or rheumatic illness
Approximately 3 cases per 100,000 per year in adults and 2 to 7 per 100,000 in Caucasian children <18 years of age. There is increased incidence and development of severe disease in African American and Hispanic populations.
Etiology and Pathophysiology
- Increased glomerular permeability to protein macromolecules, especially albumin
- Edema results primarily from renal salt retention, with arterial underfilling from decreased plasma oncotic pressure playing an additional role.
- The hypercoagulable state that can occur in some nephrotic states is likely due to loss of antithrombin III in urine.
- Primary renal disease (e.g., MCD, FSGS, MGN, IgA nephropathy)
- Secondary renal disease (e.g., diabetic nephropathy, amyloidosis, and paraproteinemias)
Mutations in genes regulating podocyte proteins identified in families with inherited nephrotic syndrome.
- Drug addiction (e.g., heroin [FSGS])
- Hepatitis B and C, HIV, CMV, parvovirus B19, toxoplasmosis, other infections
- Nephrotoxic drugs (lithium, bisphosphonates, interferon therapy, gold, bucillamine, and penicillamine)
- Vesicoureteral reflux (FSGS)
- Cancer (usually MGN, may be MCD)
- Chronic analgesic use/abuse (NSAIDs)
- Diabetes mellitus
Avoidance of known causative medications including NSAIDs, gold, penicillamine, and captopril; avoidance of heroin abuse; avoidance of high-risk sexual behaviors and tight glycemic control
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