Hypoalbuminemia

Background

• Albumin is most abundant protein in human
• Synthesized in liver
• Functions include:
  • Transport of hormones, fatty acids, and other substances
  • Maintenance of oncotic pressure
  • pH buffering
• Normal reference range 3.5–5.0 g/dL
• Known as "negative acute phase protein" as levels often drop during times of acute physiologic stress

Clinical Features

• Signs/symptoms of underlying disease (e.g. stigmata of cirrhosis, wasting)
• Third spacing of fluids due to decreased oncotic pressure (e.g. peripheral edema)

Differential Diagnosis

• Liver disease e.g. cirrhosis (most common)
• Excess renal excretion e.g. nephrotic syndrome, glomerulonephritis
• Excess bowel loss e.g. protein-losing enteropathy in Crohn's
• Burns (via plasma loss through the skin)
• Hemodilution e.g. in pregnancy
• Capillary leak e.g. in hantavirus
• Malnutrition
• Genetic mutation (rare)
• Any acute disease state e.g. sepsis, pancreatitis, Kawasaki

Evaluation

• Due to albumin's functions, certain lab values require correction for hypoalbuminemia
  • Corrected serum calcium = (0.8 * (Normal Albumin - Pt's Albumin)) + Serum Ca
  • Corrected anion gap = anion gap + [ 2.5 × (4 - albumin, g/dL) ]
  • Corrected phenytoin level = measured phenytoin level / ( (adjustment x albumin, g/dL) + 0.1)
    • Adjustment = 0.275; in patients with creatinine clearance <20 mL/min, adjustment = 0.2.

Management

• Treat underlying disease
• Replacing albumin only indicated in specific disease processes/clinical scenarios
  • With large volume paracentesis
  • Concern for SBP and creatinine >1mg/dL, BUN >30mg/dL, or T Bili >4mg/dL
  • Hepatorenal syndrome
  • Consider in acute pancreatitis if albumin <2 g/dL