Rosen & Barkin's 5-Minute Emergency Medicine Consult (482 page)

Mild cases of clinical nephritis in healthy patients with:

• No comorbid illness
  
• Strict supervision/monitoring of symptoms, diet, urine output, and medication
  
• Close follow-up with PMD and nephrology referral
  

Nephrology:

• Within 2–3 days
  

• Adherence to antibiotic and antihypertensive therapy, as indicated
  
• Restrict salt and fluid intake.
  

• Diagnosis is confirmed by biopsy showing characteristic crescent formation within renal glomeruli.
  
• Must obtain thorough history of ongoing or recent infections as possible etiology of nephritis
  
• IgA nephropathy is most common cause of nephritis.
  
• Patients require aggressive management of BP and volume status.
  

• Ikee R, Kobayashi S, Saigusa T, et al. Impact of hypertension and hypertension-related vascular lesions in IgA nephropathy.
  Hypertens Res
  . 2006;29(1):15–22.
  
• Kanjanabuch T, Kittikowit W, Eiam-Ong S. An update on acute postinfectious glomerulonephritis worldwide.
  Nat Rev Nephrol
  . 2009;5:259–269.
  
• Kunz R, Friedrich C, Wolbers M, et al. Meta-analysis: Effect of monotherapy and combination therapy with inhibitors of the renin angiotensin system on proteinuria in renal disease.
  Ann Intern Med
  . 2008;148(1):30–48.
  

See Also (Topic, Algorithm, Electronic Media Element)

• Acute Renal Failure
  
• Glomerulonephritis
  
• Nephrotic Syndrome
  

CODES

• 580.0 Acute glomerulonephritis with lesion of proliferative glomerulonephritis
  
• 580.9 Acute glomerulonephritis with unspecified pathological lesion in kidney
  
• 583.2 Nephritis and nephropathy, not specified as acute or chronic, with lesion of membranoproliferative glomerulonephritis
  

BASICS

• 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
    

• 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
    

• 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, non-nephrotic, 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/24hr) 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 pre-eclampsia, hepatitis, and drug reactions (culprits include NSAIDs, gold, penicillamine).
  

DIAGNOSIS

• Many patients are asymptomatic.
  
• Proteinuria
  
• Peripheral edema:
  
  • Mild pitting edema to generalized anasarca with ascites
    
• Hyperlipidemia
  
• Lipiduria (urine fatty casts and oval fat bodies)
  
• Postural hypotension, syncope, shock
  
• Hypertension
  
• Hematuria:
  
  • Microscopic or gross hematuria (secondary to renal vein thrombosis)
    
• Renal insufficiency to acute renal failure in some cases
  
• Tachypnea, tachycardia, with or without hypotension:
  
  • Acute onset: Suggests pulmonary embolus (PE), secondary to renal or deep venous thrombosis and hypercoagulable state
    
  • Up to 30% occurrence of PE in membranous glomerulonephritis
    
  • Chronic or exertional tachypnea due to:
    
    • Pulmonary edema
      
    • Pleural effusions
      
    • Infection risk due to immunosuppressive treatment and frequent exposure to infections such as Pneumococcus
      
    • Ascites
      
• Protein malnutrition
  

• Systemic disease such as diabetes, SLE, HIV
  
• Use of NSAIDS, gold, or penicillamine
  
• History of unintentional weight gain (due to fluid retention)
  
• History of “foamy” appearance of urine
  

Varies depending on degree of hypoalbuminemia, hemodynamic status, and etiology of nephrotic syndrome:

• Edema
  
• Hypotension/hypertension
  
• Shock
  

Urinalysis:

• Dipstick protein largely positive:
  
  • Urine specific gravity >1.025 lowers the diagnostic significance of proteinuria.
    
• Microscopic analysis for urinary casts and the presence of cellular elements:
  
  • Oval fat bodies
    
  • Free lipid droplets
    

• CBC + differential:
  
  • Anemia common
    
  • Leukocytosis: Infection
    
  • Leukopenia: Neoplastic disease or sepsis
    
  • Thrombocytopenia: Liver disease
    
• PT/PTT, international normalized ratio:
  
  • Coagulation profiles abnormal with concurrent liver disease
    
• D
  -dimer, fibrinogen, antithrombin III
  
  • Suspected thromboembolic event:
    
    • Often patients are asymptomatic with PE or renal vein thrombosis; therefore need high clinical suspicion.
      
• 24-hr urine protein, total protein to creatinine ratio
  
• Serum albumin: <3 g/dL
  
• Serum total protein
  
• Basic metabolic panel with Ca, Mg, P
  
• Lipid profile: Elevated total cholesterol, LDL, and VLDL
  
• Additional lab tests may be necessary for systemic diseases:
  
  • Examples include antinuclear antibody, serum and urine protein electrophoresis, hepatitis profile, syphilis, cryoglobulins, complement levels