胆红素一直高于正常值

本人55岁，女。这是我2013 年以来总胆红素的数据（mg/dL）。2015 年8月由于胆结石切除胆囊。

今年8月总胆红素达到 1.9， 直接胆红素 是0.3， 间接是1.6。

上周家庭医生为查明胆红素高的原因，让我做了腹部超声波。结果如下：

LIVER: Normal in size. Normal echogenicity. No focal liver lesion identified. No intrahepatic ductal dilatation.

MAIN PORTAL VEIN: The portal vein is patent with antegrade flow.

GALLBLADDER: Surgically absent.

CBD: Normal measuring up to 9.1 mm. Please note that the distal CBD, in the region of the pancreatic head, is not adequately visualized.

PANCREAS: Evaluation of the pancreas is limited secondary to overlying bowel gas. Visualized portions of the pancreas are unremarkable without significant pancreatic ductal dilatation.

RIGHT KIDNEY: 11.3 cm in length. Normal contour and echogenicity. No hydronephrosis.

IMPRESSION:

Mild biliary ductal dilatation, potentially related to post cholecystectomy state. Given clinical history of jaundice and elevated bilirubin, consider follow-up MRI/MRCP to evaluate for an occult stricture, stone, or mass. 

我眼睛不黄，皮肤不黄，没有jaundice 症状。除了HDL(56)有点低， LDL(120)和 A1C(5.8)有点高以外，其他检查结果都正常。 自我感觉良好，身体没有任何不适。请问胆红素高是什么引起的呢？有必要去做MRI 吗？