Liver function test abnormalities after traumatic brain injury: is hepato-biliary ultrasound a sensitive diagnostic tool?

This study was to evaluate the usefulness of hepato-biliary ultrasound (HBUS) for the investigation of isolated liver function tests (LFTs) abnormalities. We retrospectively reviewed HBUS reports in traumatic brain injury (TBI) patients admitted to our tertiary neuro-critical care unit (NCCU; January 2005-June 2011). We included patients receiving an HBUS for isolated LFTs derangement, excluding pre-existing hepato-biliary diseases or trauma. We assessed the temporal profile of alanine aminotransferase (ALT), bilirubin (Bil), and alkaline phosphatase (ALP). Of 511 patients, 58 received an HBUS. Of these, 47 were investigated for isolated LFTs derangement; HBUS always failed to identify a cause for these abnormalities. The HBUS was performed on day 18 (range 6-51) with the following mean values: 246 IU litre(-1) [ALT, 95% confidence interval (CI) 183-308], 24 μmol litre(-1) (Bil, 95% CI 8-40), and 329 IU litre(-1) (ALP, 95% CI 267-390); only ALT (72, 95% CI 36-107) and ALP (73, 95% CI 65-81) were deranged from admission values (both P<0.01). At NCCU discharge, both ALT (160, 95% CI 118-202) and ALP (300, 95% CI 240-360) were higher than at admission (P<0.01). Compared with HBUS-day value, only ALT improved by NCCU discharge (P<0.05), while both were recovering by hospital discharge (ALT 83, 95% CI 59-107; ALP 216, 95% CI 181-251; P<0.01). At hospital discharge, ALP remained higher than at admission (P<0.01). In TBI patients, HBUS did not appear sensitive in detecting causes for isolated LFT abnormalities. Both ALT and ALP worsened and gradually recovered. Their abnormalities did not prevent NCCU discharge. ALP recovered more slowly than ALT. TBI and its complications, critical illness, and pharmacological strategies may explain the LFTs derangement.