Question

Anti-thrombin III levels in disseminated intravascular coagulation

• A. Are decreased
• B. Are increased
• C. Remain the same
• D. Are variable

Hint:

Think about what happens to any clotting inhibitor when clotting runs out of control everywhere.

Answer 1

The Correct Option is A

Step 1: Recall what antithrombin III does.
Antithrombin III is a natural protein in the blood that blocks thrombin and several other clotting factors, mainly factor Xa. It is the body's main brake on clot formation.

Step 2: Recall what happens in disseminated intravascular coagulation (DIC).
In DIC, a triggering illness such as sepsis, placental abruption, or severe preeclampsia switches on clotting all over the body at once. Small clots form in many vessels, using up clotting factors and platelets faster than the liver can replace them.

Step 3: Follow what happens to antithrombin III during this process.
Because antithrombin III is consumed while it tries to neutralize the excess thrombin being generated everywhere, its blood level falls. This drop is one of the laboratory clues used to support a diagnosis of DIC, along with a low platelet count, low fibrinogen, and raised D-dimer.

Step 4: Rule out the other options.
Antithrombin III does not rise or stay the same in DIC, since the underlying process actively uses it up rather than sparing or increasing it. Calling the change variable also misses the point, because the direction of change is consistently downward.

Final Answer:
Antithrombin III is consumed along with other clotting factors in DIC, so its level falls.
\[ \boxed{\text{Decreased}} \]