My son age 6yr is having his liver size 138 mm. is it safe? what is normal size?

Abnormal size: For male children the liver span should be 5 cm (50mm). Enlarged liver for children usually occur with other symptoms and rarely just occur alone. There are a variety of causes that can include Genetic disorder, infection, medication use, tumors - benign and malignant, heart and vascular disorders as well as blockage near and around the gall bladder. This must be evaluated by his doctor