肝硬変になるとなぜ血小板数が減るのか？

肝硬変と血小板数の減少の病態生理がよくわからなくて調べたが、これまたまだよくわかっていないらしい。肝硬変→門脈圧亢進→脾腫→pancytopenia
はひとつの説明だが、それならなぜfibrosisの指標とthrombocytopeniaの減少が相関するのかを説明できていない。
2007年の論文の著者によれば、肝硬変になると
thrombopoietinなどの血小板産生に必要なタンパク質合成が減るから

あるいは血小板に有害な物質の代謝ができなくなるから

ということを可能性としてあげている。

Liver fibrosis is associated with decreased peripheral platelet count in patients with chronic hepatitis B and C. - Karasu Z - Dig Dis Sci - 01-JUN- 2007; 52(6): 1535-9 (MEDLINE® is the source for the citation and abstract of this record )

We investigated the relationship between the peripheral platelet count and the degree of fibrosis in patients with chronic viral hepatitis.
Thrombocytopenia is a common complication of chronic liver diseases, but its pathogenesis is not clear.

In conclusion, a decrease in peripheral platelet count may be a sign of an increase in the degree of fibrosis during the course of chronic viral hepatitis B and C and factors other than hypersplenism may play a role in this decrease in the peripheral platelet count.

peripheral platelet count (PPC)
chronic hepatitisC(CHC)
Decreasing PPC and increasing hepatic fibrosis: Which one is the cause and which one is the result? In most earlier studies, authors discussed the effect of decreasing PPC on fibrosis. However, we believe that decreasing hepatocyte mass accompanying increasing fibrosis, secondary to progressive liver injury, causes a decrease in production of thrombopoietin or other humoral factors, or a decrease in the clearance of some toxicmolecules, and leads to decreased PPC, unrelated to hypersplenism.