Nephrotic Syndrome

Nephrotic Syndrome is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • A clinical syndrome of proteinuria (>3.5 g/1.73 m2/24 hr), hypoalbuminemia (<3 g/dL), severe hyperlipidemia (total cholesterol often >10 mmol/l) (380 mg/dL), clinical evidence of peripheral edema, with risk for thrombotic disease
  • Includes both primary (idiopathic) and secondary forms
  • Associated with many types of kidney disease

Epidemiology

Based on definitive diagnosis

  • Diabetic nephropathy: most common cause of secondary nephrotic syndrome (1)
  • Minimal change disease (MCD)
    • Most common cause of nephrotic syndrome in children <10 years (90%)
    • Peaks at 2 to 8 years of age
    • Associated with drugs (mainly NSAIDs) or lymphoma in adults
  • Amyloidosis: 7–14% of idiopathic nephrotic syndrome—two renal types 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%)
    • May be primary or secondary associated with malignancy, Hep B, autoimmune diseases, thyroiditis, and certain drugs
  • Membranoproliferative glomerulonephritis (MGN)
    • May be primary or secondary
    • May present in the setting of a systemic viral or rheumatic illness

Etiology and Pathophysiology

  • Increased glomerular permeability to protein macromolecules, especially albumin
  • Podocytes injury is the most common finding in diseases that cause primary nephrotic syndrome.
  • Edema results primarily from renal salt retention, with arterial underfilling from decreased plasma oncotic pressure playing an additional role.
  • Hyperlipidemia is thought to be a consequence of increased hepatic synthesis resulting from low oncotic pressure and urinary loss of regulatory proteins.
  • The hypercoagulable state that can occur in some nephrotic states is likely due to loss of antithrombin III in urine.
  • Primary renal disease:
    • MCD
    • FSGS
    • MGN
    • IgA nephropathy
  • Secondary renal disease (associated primary renal disease shown in parentheses):
    • Diabetic nephropathy
    • Amyloidosis
    • LN
    • FSGS
    • Infections (MGN)
    • Cancer (MCD or MGN)
    • Drugs (MCD or MGN)

Genetics
Genetic factors are likely to play a role in susceptibility to the various nephrotic syndromes, although these have not been sufficiently defined to be useful clinically.

Risk Factors

  • Drug addiction (e.g., heroin [FSGS])
  • Hepatitis B and C, HIV, other infections
  • Immunosuppression
  • Nephrotoxic drugs
  • Vesicoureteral reflux (FSGS)
  • Cancer (usually MGN, may be MCD)
  • Chronic analgesic use/abuse (NSAIDs)
  • Preeclampsia
  • Diabetes mellitus

General Prevention

In general, there are few preventive measures, including avoidance of known causative medications including NSAIDs, gold, penicillamine, and captopril; avoidance of heroin abuse and tight glycemic control

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Citation

* When formatting your citation, note that all book, journal, and database titles should be italicized* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Nephrotic Syndrome ID - 116404 ED - Baldor,Robert A, ED - Domino,Frank J, ED - Golding,Jeremy, ED - Stephens,Mark B, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116404/all/Nephrotic_Syndrome PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -