What is the prognosis of antithrombin III (ATIII) deficiency?

Updated: Mar 04, 2020
  • Author: James L Harper, MD; Chief Editor: Hassan M Yaish, MD  more...
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Prognosis depends on 3 variables: the degree of the deficiency, the nature of the observed clot, and the number of clots seen.

  • Prognosis for homozygous-deficient antithrombin III deficiency is grim. Typically, severe thrombotic complications arise in neonates. Prognosis for survival into adulthood is good for patients who are heterozygous deficient. The peak risk for thrombotic complications does not arise until the third and fourth decades of life.

  • The nature of the observed clot is an important variable. A clot that occurs in the mesenteric circulation or other central vein carries a more ominous prognosis than clots in the peripheral circulation. Patients with clots in the mesenteric circulation are often best treated with indefinite anticoagulation, even after a single episode.

  • Clots that recur, particularly those that recur either in the central or mesenteric circulation, are of important prognostic significance. Patients with such clots are much more likely to continue to experience thrombotic episodes and eventually to suffer either a life-threatening clot or suffer needlessly from the complications of the thrombi. One thrombotic event may be treated successfully with limited warfarin therapy, particularly if no other prothrombotic condition is present. Patients who experience multiple thrombi are often best treated with indefinite warfarin therapy.

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