*Ketogenic Diets Exacerbating Hypercholesterolemia in APOE Variants and APOB Mutations-Potential Role for Measuring Intestinal Absorption of Lipids

Abstract

Lead Author's Financial Disclosures Nothing to disclose. Study Funding None. Background/Synopsis Familial Hypercholesterolemia (FH) is caused primarily by mutations in either LDL receptor, APOB, or PCSK9 genes. There are other genetic causes of LDL elevation including APOE4 variants. Objective/Purpose We present two patients with markedly elevated LDL suspicious for FH who were subsequently diagnosed with APOE3/4 variants while on ketogenic diets. We also present a patient with a known APOB mutation who had a marked elevation of LDL on a ketogenic diet. Methods Case 1: 58-year-old male with no prior medical history was found to have elevated cholesterol of 600mg/dL and LDL>455mg/dL while on a ketogenic diet. Prior to initiating the diet, his cholesterol was 206mg/dL and LDL was 132mg/dL. Genetic testing revealed a ApoE3/4 variant. His most recent cholesterol increased to 706mg/dL and LDL to >500mg/dL. Case 2: 53-year-old male with hypertension cholesterol of 282mg/dL and LDL of 212mg/dL went on a ketogenic diet and lost 100lbs. Follow up lipid panel demonstrated a cholesterol of 400mg/dL and LDL of 317mg/dL. Genetic testing revealed a APOE3/4 variant. Case 3: 45-year-old female with FH and known APOB missense mutation went on a ketogenic diet for weight loss. Prior to initiating the diet, her total cholesterol was 311 mg/dL and LDL was 211 mg/dL. While on the ketogenic diet, her total cholesterol was 550 mg/dL and LDL was 454 mg/dL. Her LDL decreased to 276mg/dl on a less strict ketogenic diet. Results All three patients had a normal exercise stress test, normal carotid duplex ultrasound, and coronary calcium score of zero. They refused the initiation of a statin. All 3 patients had the Boston Heart Cholesterol Balance Test performed that directly measures the absorption markers (beta-sitosterol, campesterol and cholestanol) for circulating plasma cholesterol. Only the patient with the APOB mutation had increased intestinal absorption of cholesterol, suggesting a response to ezetimibe. She agreed to initiate ezetimibe, her LDL subsequently decreased by 52% to 132mg/dl. Conclusions We hypothesize patients with APOE variants and APOB mutations could have an exaggerated elevation of their LDL levels while on ketogenic diets. Although these 3 patients did not demonstrate progressive atherosclerosis, the long-term effect of this diet is unknown. We recommend that all patients on a ketogenic diet have their LDL monitored and if there is a significant increase, undergo genetic testing for FH, APOE and other genetic variants. Since this patient group is often reluctant to start statins, the Cholesterol Balance Test may be useful to identify patients who may respond well to ezetimibe. Nothing to disclose.