602 EP044 – The use of liver function testing to prevent splenic rupture in athletes returning to play after infectious mononucleosis

Background Splenomegaly is common in infectious mononucleosis (IM) and splenic rupture during the return-to-play process is a known complication.¹ Because IM has a variable disease course, safe return-to-play guidelines vary.² Although splenic ultrasound is the gold standard for determining splenomegaly, there is variability in baseline spleen sizes and serial ultrasounds are not feasible in all clinical settings. Effective monitoring of splenomegaly in athletes diagnosed with IM may reduce the risk of splenic rupture and its associated morbidity/mortality. Objective To evaluate the correlation of liver function testing (LFT) and spleen size in athletes diagnosed with IM. Design We prospectively collected serial aspartate aminotransferase (AST), alanine transaminase (ALT) levels, and ultrasound-measured spleen sizes over an average course of 24 days (range: 18–33 days) post symptom onset in university athletes who had been diagnosed with IM. The effects of AST, ALT, and days from symptom onset were analyzed using multivariable mixed-effects linear regression models. Setting University athletes at a single institution. Patients Seven university-aged athletes with laboratory confirmed diagnoses of IM. Interventions Patients received serial LFT and splenic ultrasound measurements until resolution of symptoms and full return to sport. Main Outcome Measurements AST/ALT values, spleen size Results Levels of AST and ALT were significantly correlated with spleen size. For each 10-unit increase in AST and ALT values, spleen size increased by 0.1cm (p=0.007) and 0.09cm (p = 0.008) respectively. Decreasing levels of ALT and AST correlated with a decrease in spleen size. Normalization of AST/ALT values correlated with return of spleen size to baseline. Conclusions Liver function testing provides sport physicians with a means to monitor splenomegaly in athletes who have been diagnosed with IM. This may be useful in guiding the return-to-play process for athletes who may otherwise be at risk for splenic rupture. References Sylvester JE, Buchanan BK, Silva TW. Infectious mononucleosis: rapid evidence review. Am Fam Physician 2023;107(1):71–78. Putukian M, McGrew CA, Benjamin HJ, Hammell MK, Hwang CE, Ray JW,... Wilson K. American medical society of sports medicine position statement: mononucleosis and athletic participation. Clinical Journal of Sport Medicine 2023;33(4):359–367.