Endocrine Abstracts

Introduction

Hypercholesterolemia may develop due to primary and secondary causes. Diabetes mellitus, hypothyroidism, nephrotic syndrome and liver diseases are among the most common causes of secondary hyperlipidemia. Here, we will present a case with severe hyperlipidemia due to primary sclerosing cholangitis(PSC).

Case

A 36-year-old male patient was admitted to our outpatient clinic due to severe hypercholesterolemia. It was learned in his history that he had increased liver enzymes for 3 years. He was diagnosed with PSC 4 months ago and liver transplantation was planned. The patient was using ursodeoxycholic acid 2x500 mg treatment. On physical examination, blood pressure was 120/70 mmHg, heart rate was 78 beats/minute and he had icteric appearance. Xanthoma, xanthelasma, arcus cornea was not observed. In laboratory tests, AST, ALT, ALP, GGT, total bilirubin, total cholesterol, LDL, triglyceride, VLDL, HDL were 111 U/l, 108 U/l, 1037 U/l, 301 U/l, 17 mg/dl, 574 mg/dl, 499 mg/dl, 348 mg/dl, 70 mg/dl, 5 mg/dl, respectively. The patient had no other comorbid diseases other than PSC. There was no history of early cardiovascular disease or sudden death in family members. It was learned that the patient’s LDL value was 102 mg/dl 5 years ago. The cause of hypercholesterolemia in the patient was considered depending on the PSC. Statin therapy was not considered due to impaired liver function tests. We planned to start cholestyramine 12 grams per day.

Conclusion

PSC is a liver disease with biliary obstruction. Lipid disorder due to biliary obstruction is associated with lipoprotein X (LpX). LpX is a abnormal low density lipoprotein. It is unable to exert negative feedback on the cholesterol synthesis rate limiting enzyme hydroxymethyglutaryl coenzyme A (HMG-CoA) reductase. In contrast, the presence of LpX increases the activity of HMG-CoA reductase in the liver with increased hepatic cholesterol synthesis. Patients with biliary obstruction have increased LDL and decreased HDL. Hypercholesterolaemia improves with removal of obstruction or liver transplantation. LDL apheresis, statins and cholestyramine decrease cholesterol levels in patients with PSC.