Nephrotic Syndrome
Basics
Description
Description
- Diseases causing defect in glomerular filtration barrier, producing proteinuria:
- Proteinuria >3 g in 24 hr
- Hypoalbuminemia (serum albumin <3 g/dL)
- Peripheral edema due to hypoalbuminemia
- Hypogammaglobulinemia
- Hyperlipidemia (fasting cholesterol >200 mg/dL)
- Urine fat (oval fat bodies, fatty/waxy casts)
- Glomerular basement membrane altered by:
- Immune complexes
- Nephrotoxic antibodies
- Nonimmune mechanisms
- Result: More permeable glomerular membranes and excretion of albumin and large proteins
Pathophysiology
Pathophysiology
- Proteinuria due to increased filtration within renal glomeruli
- Edema due to sodium retention and hypoalbuminemia
- Postural hypotension, syncope, and shock due to severe hypoalbuminemia
- Hyperlipidemia due to hepatic lipoprotein synthesis stimulated by decreased plasma oncotic pressure
- Cumulative thromboembolism risk increased if:
- Hypovolemia
- Low serum albumin
- High protein excretion
- High fibrinogen levels
- Low antithrombin III levels
Etiology
Etiology
- Due to primary renal or systemic diseases
- Membranous nephropathy:
- Primary cause of nephrotic syndrome in adults
- Other causes include chronic infection (hepatitis B virus, hepatitis C virus, autoimmune disorders)
- Renal biopsy shows involvement of all glomeruli
- Women have better prognosis
- 30% may slowly progress to renal failure
- Renal vein thrombosis causes sudden loss of renal function
- Treat with steroids and cytotoxic agents in severe cases
- Minimal change disease:
- Most common cause (90%) of nephrotic syndrome in children
- Other causes: Idiopathic, NSAIDs, paraneoplastic syndrome associated with malignancy (often Hodgkin lymphoma)
- Best prognosis among all nephrotic syndromes
- Good response to steroids
- Focal segmental glomerulosclerosis (FSGS):
- Young patients (15–30 yr) with nephrotic syndrome
- Presents with high BP, renal insufficiency, proteinuria, microscopic or gross hematuria
- Causes include HIV, heroin abuse, obesity, hematologic malignancies
- Primary FSGS responds to steroids
- Secondary FSGS treated with ACE inhibitors (ACEI)
- Collapsing FSGS usually seen in HIV patients
- Membranoproliferative glomerulonephritis:
- May present with nephrotic, nonnephrotic, or nephritic sediment
- Complement levels are persistently low
- Supportive care: Steroids may be helpful in children
- Aspirin and dipyridamole may slow progression
- Diabetes mellitus/diabetic nephropathy:
- Most common secondary cause of nephrotic range proteinuria in adults
- Microalbuminuria (30–300 mg/24 hr) is primary indicator of renal disease
- Worsening of renal function in 5–7 yr
- Does not cause rapid decline in renal function
- Strict control of blood sugar and ACEI therapy slow progression
- Monoclonal gammopathies:
- Include amyloidosis, multiple myeloma, and light-chain nephropathy
- Renal manifestations include proteinuria, nephrotic syndrome, nephritic syndrome, and acute renal failure
- Lab findings include pseudohyponatremia, low anion gap, hypercalcemia, and Bence Jones proteinuria
- Congo red stain of amyloid shows apple-green birefringence in polarized light
- Supportive care: Steroids and melphalan have some benefit
- Systemic lupus erythematosus (SLE):
- Can present initially as a nephritic process, with progression to nephrotic syndrome
- HIV-associated nephropathy:
- FSGS is most common nephropathy
- Collapsing glomerulopathy in seropositive HIV carriers with supernephrotic syndrome results in end-stage renal failure that is rapidly progressive (months)
- Other causes include preeclampsia, hepatitis, and drug reactions (culprits include NSAIDs, gold, penicillamine)
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Citation
Schaider, Jeffrey J., et al., editors. "Nephrotic Syndrome." 5-Minute Emergency Consult, 6th ed., Lippincott Williams & Wilkins, 2020. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307091/all/Nephrotic_Syndrome.
Nephrotic Syndrome. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307091/all/Nephrotic_Syndrome. Accessed December 3, 2024.
Nephrotic Syndrome. (2020). In Schaider, J. J., Barkin, R. M., Hayden, S. R., Wolfe, R. E., Barkin, A. Z., Shayne, P., & Rosen, P. (Eds.), 5-Minute Emergency Consult (6th ed.). Lippincott Williams & Wilkins. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307091/all/Nephrotic_Syndrome
Nephrotic Syndrome [Internet]. In: Schaider JJJ, Barkin RMR, Hayden SRS, Wolfe RER, Barkin AZA, Shayne PP, Rosen PP, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. [cited 2024 December 03]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307091/all/Nephrotic_Syndrome.
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