BEYOND THE OBVIOUS ABNORMAL LABORATORY VALUE. H. Jasti 1 , R. Granieri 1 ; 1 University of Pittsburgh, Pittsburgh, Pennsylvania LEARNING OBJECTIVES: 1) Recognize secondary causes of hypercholesterolemia. 2) Recognize the association between hypercholesterolemia and hypothyroidism. CASE INFORMATION: A 47-year-old male with hypertension and diabetes presented for a new visit. He endorsed occasional myalgias and constipation. He denied fatigue, weakness, cold intolerance, or dry skin. On physical, blood pressure was 150/86 and pulse was 74. The remaining exam was unremarkable, including the absence of tendinous xanthomas and delayed DTRs. Old records revealed a diagnosis of hypercholesterolemia (295 mg/dL) and hypertriglyceridemia (1200 mg/dL), with subsequent initiation of gemfibrozil. His lipid levels continued to be elevated 6 months after initiation of the medication. Subsequent testing revealed an elevated TSH and abnormal TFTs, consistent with a picture of hypothyroidism. Levothyroxine was started. Upon follow-up in 2 months, the TSH levels had decreased; cholesterol levels had also declined modestly. Further follow-up 4 months later demonstrated normal TSH levels and significantly decreased cholesterol (220 mg/dL) and triglyceride (480 mg/dL) levels. DISCUSSION: Significant hyperlipidemia may be present in the absence of clinical features; thus, secondary causes need to be considered before the initiation of lipid-lowering therapy. These include Type II diabetes, chronic renal insufficiency, nephrotic syndrome, cholestatic liver disease, obesity, smoking, alcohol, steroid, and oral contraceptive use. Hypothyroid patients also display a variety of patterns of lipid abnormalities, including elevated cholesterol, triglyceride, LDL levels. The main mechanism is a decrease in the number of LDL cell receptors, resulting in an increase in LDL levels. Other mechanisms include a diminished secretion of cholesterol into bile and reduced lipoprotein lipase activity, resulting in hypertriglyceridemia. The severity of the hypothyroidism may play a role in treatment, since many studies show a more significant improvement in the lipid levels in those with a more severe form of hypothyroidism. The evidence is less clear regarding the significance of the relationship between subclinical hypothyroidism and elevated cholesterol levels. In general, those with overt hypothyroidism seem to respond best to levothyroxine treatment and subsequently show a decline in their cholesterol levels, whereas those with subclinical hypothyroidism seem to need additional lipid-lowering agents. In conclusion, this case underscores the importance of identifying secondary causes of hypercholesterolemia before initiating treatment for an apparent lipid abnormality.