Abstract Sergio Fazio, MD, PhD, FNLA Familial Combined Hyperlipidemia

The most common presentation of altered lipid levels in clinic includes abnormal levels of multiple parameters, most commonly HDL, triglycerides, and total cholesterol. Although the very definition of combined dyslipidemia involves the presence of more than one abnormality in the lipid panel, it is often forgotten that there are statistical, biological, and methodological correlations between the components of the panel. For example, elevated triglycerides are linked to lower HDL levels and higher total cholesterol levels and also influence the determination of HDL levels and the calculation of LDL levels. The practitioner should keep in mind that combined dyslipidemia refers to abnormal levels of triglycerides accompanied by elevated LDL and depressed HDL. This may seem to repeat the initial statement, but in fact the correlation between total and LDL cholesterol is lost in combined dyslipidemia, which means that in most cases of elevated triglycerides total cholesterol is elevated but LDL cholesterol is actually reduced. When the condition appears to be inherited, the presentation may mimic Familial Hypercholesterolemia (elevated LDL cholesterol) with a varying phenotype of episodic hypertriglyceridemia. The cause is supposed to be uncontrolled synthesis of apoB and unregulated packaging and export of VLDL. If the initial abnormality is an increased output of lipoproteins, then it is easy to visualize how the full lipid phenotype includes both elevated triglycerides (increased production from the liver) and elevated LDL (reduced clearance by an overwhelmed receptor system). Although very common, this inherited condition does not currently have a genetically defined basis. In addition, it resembles the common dyslipidemia of diabetes and renal disease. In this lecture, I will review diagnostic and therapeutic approaches to the patient with inherited or acquired combined hyperlipidemia.