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.