Examkin

Question

Difficulty: Very hardInterpreting Laboratory Results

A 58-year-old man is evaluated in the intensive care unit for persistent oozing from his central venous catheter insertion site. He was admitted two days ago with a large esophageal variceal hemorrhage requiring endoscopic banding. His past medical history is significant for alcohol use disorder and advanced cirrhosis. His temperature is 37.2∘C37.2^\circ\text{C} (99.0∘F99.0^\circ\text{F}), blood pressure is 105/65 mmHg105/65 \text{ mmHg}, and pulse is 98/min98/\text{min}.

Laboratory studies show:

TestResultReference Range
Hemoglobin8.2 g/dL8.2 \text{ g/dL}13.5−17.5 g/dL13.5-17.5 \text{ g/dL}
Platelet count55,000/mm355,000/\text{mm}^3150,000−400,000/mm3150,000-400,000/\text{mm}^3
Prothrombin time (PT)28 seconds28 \text{ seconds}11−15 seconds11-15 \text{ seconds}
Activated partial thromboplastin time (aPTT)62 seconds62 \text{ seconds}25−40 seconds25-40 \text{ seconds}
Fibrinogen95 mg/dL95 \text{ mg/dL}200−400 mg/dL200-400 \text{ mg/dL}
D-dimer1,800 ng/mL FEU1,800 \text{ ng/mL FEU}<500 ng/mL FEU<500 \text{ ng/mL FEU}
Factor V activity32%32\%70−120%70-120\%
Factor VIII activity195%195\%50−150%50-150\%

Based on the laboratory results, which of the following best explains this patient's coagulation profile?

  1. Diminished hepatic synthetic function with intact endothelial factor productionAnswer
  2. B
    Systemic activation of the coagulation cascade with widespread factor consumption
  3. C
    Impaired gamma-carboxylation of glutamic acid residues on coagulation proteins
  4. D
    Primary systemic activation of plasminogen without concurrent thrombin generation
  5. E
    Dilutional depletion of coagulation factors following fluid and blood administration

Answer

Diminished hepatic synthetic function with intact endothelial factor production
The correct answer identifies diminished hepatic synthesis with intact endothelial production. In advanced liver disease, hepatocyte destruction impairs the synthesis of almost all coagulation factors, leading to low Factor V levels, low fibrinogen, and prolonged PT/aPTT. However, Factor VIII is synthesized primarily by extrahepatic endothelial cells. In cirrhosis, Factor VIII levels are typically elevated due to reduced hepatic clearance of the von Willebrand factor/Factor VIII complex and an acute-phase response from endothelial activation. This discordant profile (low Factor V, high Factor VIII) distinguishes liver failure from DIC, where both factors would be consumed.

Step-by-Step Solution

1
Analyze the basic coagulation profile and CBC in the context of the patient's history.
The patient has advanced cirrhosis with thrombocytopenia, low fibrinogen, prolonged PT/aPTT, and elevated D-dimer.
These findings are non-specific and can occur in both liver failure coagulopathy and Disseminated Intravascular Coagulation (DIC).
2
Evaluate the specific factor activities to differentiate the etiology.
Factor V is notably low (32%), while Factor VIII is markedly elevated (195%).
Specific factor levels help distinguish between systemic consumption and isolated organ synthetic failure.
3
Correlate factor levels with their sites of synthesis and pathophysiology.
Factor V is synthesized by hepatocytes and falls in liver failure. Factor VIII is synthesized by endothelial cells and remains normal or becomes elevated in liver failure. In DIC, both are consumed and would be low.
Understanding the distinct synthesis site of Factor VIII allows it to be used as a discriminator. Since Factor VIII is elevated, DIC is ruled out, confirming advanced liver failure as the sole cause.

Key Concept

Factor VIII is synthesized by endothelial cells and remains normal or elevated in liver failure, whereas it is consumed and low in DIC. This distinction is critical for differentiating liver failure coagulopathy from DIC in patients with bleeding, thrombocytopenia, and elevated D-dimer.
Rate this question

Topics

Interpreting Laboratory Results

More questions from this topic