Discussion
To our knowledge, this is the first systematic review to evaluate LFTs and USS in IM. Abnormal LFTs are an expected feature in IM; many units will routinely do blood tests to assess liver function on admission. The NICE clinical knowledge summary mentioned clinicians should consider blood test for LFTs in IM; based on expert opinion.37The utility of this practice is unclear.
Our systematic review found around two thirds of patients had elevated transaminases; this is lower than other reports of 80-90%2. This difference may be attributed to timing of LFT measurements and the heterogenous population of the systematic review. It is commonly accepted that time to resolution of abnormal LFTs from presentation with IM is around three to four weeks 38. However, the median reported time to resolution was eight weeks; a small minority of patients had persistent derangement after 6 months.
The population affected with IM are generally young and healthy. Evidence from the literature suggest serial measures of LFTs following discharge is not necessary, given the derangement in liver function is self-limiting, and no patient developed any sequalae of decompensated liver disease or received any intervention.
EBV infection is an extremely rare cause of acute liver failure. One US study included a total of 1887 adults with acute liver failure, they found four cases (0.21%) were EBV-related acute liver failure.39 Three of these cases were considered to be “probable” EBV-related as EBV was not confirmed by serological tests and liver tissue biopsy. One out of the four of the patients was immunocompromised. Two patients did not have typical symptoms of IM. In addition, acute liver failure occurred in early disease; all presented with jaundice and median time from symptom to presentation with liver disease was 13 days.
We also explored the role of abdominal ultrasound in IM. From the authors’ experiences, some units will perform ultrasound to evaluate for hepatosplenomegaly in the context of deranged LFTs, however, this was not reflected in the literature as only two studies evaluated ultrasound of the abdomen. All patients were found to have splenomegaly and around half were found to have hepatomegaly. It is expected that patients would have hepatosplenomegaly as a consequence of IM, thus the advice to avoid contact sport is given to all patients. Although limited data on ultrasound, ultrasound findings did not influence management. It is worth noting that the presence of right upper quadrant pain in the context of IM may be suggestive of acalculous cholecystitis, ultrasound may be indicated here for further evaluation.11
Our findings also raise questions on the need for routine LFTs assessment in IM as this has the potential to lead to a cascade of unnecessary serial measurements in the community and abdominal ultrasound which has no effects on patients’ outcomes.
Changing the practice with regards to serial LFTs assessment would avoid unnecessary use of limited resources, currently highlighted by national shortage of blood bottles in the UK.40 In addition, avoid unnecessary consultations with the general practitioners.
Limitations to this systematic review include the varied methods for ascertaining diagnosis of IM and incomplete follow up in LFT assessment with varying lengths of follow-up across studies. Even within studies, there is varying interval or lack of information for repeating LFTs among individual patients. Generally, there was no standardized protocol for assessment of LFTs, thus limiting accurate assessment of time to resolution. There are also few studies on abdominal ultrasound in IM patients.