Abstract
Extremes of body weight are not uncommon in the modern world and include anorexia
nervosa (AN) and obesity. Both conditions are associated with increased morbidity
and mortality: AN has the highest mortality rate of all mental illnesses and unfortunately
obesity has reached epidemic proportions and is a well-recognized risk factor for
cardiovascular disease including venous thromboembolism (VTE). This article summarizes
the current understanding of hemostatic changes of these extremes of body weight.
The hemostatic changes of AN have not been well described. Severe AN is associated
with pancytopenia with decreased bone marrow cellularity, which causes a mild thrombocytopenia.
Platelet hyperaggregability has been recognized in AN and has been attributed at least
in part to increased adrenoceptor density. Obesity and the metabolic syndrome are
associated with prothrombotic changes, which have been well characterized and related
to complex adipocyte-induced inflammatory changes, including increased levels of plasminogen
activator inhibitor type 1, von Willebrand factor, fibrinogen, and other evidence
of increased coagulation and platelet activation. Accumulating evidence suggests a
significant role for increased tissue factor expression and signaling in this relationship,
with increased tissue factor expression present in adipose and possibly systemic tissues,
induced by adipose-generated cytokines. Intriguingly, the hemostatic changes do not
seem to increase with increasing BMI, although the risk of VTE increases with BMI,
suggesting that decreased venous flow due to venous enlargement may play the most
important role in increased VTE risk with obesity.
Keywords
obesity - anorexia nervosa - body mass index - hemostasis
