Thrombopoietin in acute liver failure

Thrombopoietin (TPO) is the primary regulator of platelet production. TPO is produced in the liver and levels are low in patients with cirrhosis. Because thrombocytopenia is common in patients with acute liver failure (ALF), we measured TPO concentrations (normal TPO range, 31 to 136 pg/mL) in 51 patients with ALF to determine if low levels were associated with thrombocytopenia. TPO levels from hospital day 2 were elevated in 43% of patients, normal in 47%, and decreased in 10% of patients. Levels were higher in acetaminophen-induced than in non-acetaminophen-induced ALF, 160 (12 to 549) pg/mL versus 73 (18 to 563) pg/mL, respectively, P = .031. TPO levels did not correlate with platelet count and were not related with survival or infection. We analyzed daily TPO levels for the first week of hospitalization in 12 patients with acetaminophen-induced ALF and observed a gradual increase from a median admission level of 50 (5 to 339) pg/mL to a median peak level of 406 (125 to 1,081) pg/mL occurring on day 5 (3 to 6). Platelets were reduced in 11 of the 12 patients with a nadir platelet count of 52 (19 to 156) × 10⁹ cells/L occurring on day 5.5 (1 to 6). The peak TPO level did not correlate with the nadir platelet count (P = .43). In conclusion, the normal inverse relationship between platelet count and TPO levels was not observed in ALF. Despite severe hepatic dysfunction, serum TPO levels were initially normal and increased during hospitalization in acetaminophen-induced ALF, but did not prevent the development of thrombocytopenia.