Each of the following are risk factors for secondary hyperlipidemia except?

Secondary hyperlipidemia refers to elevated lipid levels in the blood due to underlying conditions or factors, as opposed to primary hyperlipidemia, which is often genetic in origin. The correct answer addresses a specific genetic disorder that directly influences cholesterol metabolism rather than being a result of secondary causes.

Autosomal dominant disorders affecting the LDL receptor, such as familial hypercholesterolemia, lead to primary hyperlipidemia. This genetic condition results from mutations that affect how the body clears low-density lipoprotein (LDL) cholesterol from the bloodstream. Individuals with this disorder have elevated cholesterol levels regardless of other risk factors.

In contrast, the other options presented are all known to contribute to secondary hyperlipidemia. Obesity can lead to increased fatty acid release from adipose tissue, which in turn raises triglycerides and LDL cholesterol. Diabetes mellitus is associated with insulin resistance, which influences lipid metabolism and often leads to increased triglycerides and low HDL cholesterol levels. A high cholesterol diet can increase blood lipid levels, particularly when combined with other risk factors such as obesity or metabolic dysfunction.

Thus, the autosomal dominant disorder of the LDL receptor is distinct as it represents a primary, hereditary cause of hyperlipidemia rather than a secondary factor.