Hi welcome to health care magic forum.
First,xray isnt good test for verifying liver
size. it is not specific and further tests are necessary such as ultrasound
or ct scan
.also he should do liver and blood tests. most common causes are benign such as infection but sometimes it may indicate metabolic disorder or hematologic disorder. all in all you dont have to be worried but do further testing.
Hope I have answered your query.Regards