A 40-year-old woman has lipid investigations suggesting familial hypercholesterolemia (increased cholesterol, increased low-density lipoprotein , and normal triglycerides). This condition is characterized by increased risk for premature atherosclerosis and by the occurrence of tuberous and tendon xanthomas. Before making the assumption of familial hypercholesterolemia, secondary causes need to be considered. Which of the following conditions is most likely to cause secondary hyperlipidemia?