A 48-year-old man comes to the office for a follow-up visit. He was diagnosed with hypercholesterolemia 6 months ago and has been strictly following dietary and lifestyle modifications as advised. The patient has no other medical problems. He does not use tobacco, alcohol, or illicit drugs. His father has diabetes mellitus and coronary artery disease. The patient's blood pressure is 126/70 mm Hg and BMI is 33.1 kg/m². Physical examination is normal. Laboratory studies show a current LDL level of 190 mg/dL. Which of the following should be obtained before starting statin therapy in this patient?

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11ec160b_3b88_e04a_9249_ef3adb5cd913_MD0001_00 This patient has a severe elevation in his LDL level. This degree of hyperlipidemia, especially with a family history of coronary artery disease, suggests familial hypercholesterolemia and confers a very high risk for cardiovascular events. HMG-CoA reductase inhibitors (statins) are the first-line therapy for most patients with hypercholesterolemia and have been proven to reduce the risk of cardiac events. The statins are structural analogs of HMG-CoA and competitively inhibit HMG-CoA reductase, the enzyme responsible for the rate-limiting step in cholesterol synthesis. Serious side effects of statins include myopathy and hepatitis. Although mild elevations of liver enzymes are common, significant liver injury (aspartate transaminase/alanine transaminase levels more than 3 times the upper limit of normal) is seen in less than 1% of patients and is usually reversible if the medication is discontinued. Liver function tests are recommended before starting statin therapy; otherwise, routine monitoring is not necessary unless symptoms of hepatic injury develop (eg, fatigue, malaise, anorexia). (Choice A) Apolipoprotein-B (Apo-B) is a structural protein found in atherogenic lipoprotein particles. Each lipoprotein particle contains only a single Apo-B molecule, so measurement of Apo-B levels can quantify the LDL particle count. Patients with increased LDL particle counts are at greater risk for cardiovascular events. However, measurement is of limited clinical utility and would not change management in this case. (Choice B) Statin medications do not cause any significant hematologic toxicity. (Choice C) Lipoprotein lipase deficiency can cause familial hypertriglyceridemia (heterozygous deficiency) and chylomicronemia (homozygous deficiency) syndromes. These conditions present with elevated serum triglyceride levels but do not cause elevation in LDL levels. (Choice E) Because cholesterol is a precursor in the synthesis of adrenocortical and gonadal steroid hormones, statin medications can, in theory, cause hypogonadism or hypoadrenalism. Clinically, however, there are no significant alterations in serum cortisol or gonadal steroid levels unless patients are also on other adrenal enzyme inhibitors (eg, ketoconazole, aminoglutethimide). (Choice F) Statins have no significant renal side effects. In rare instances, they can cause rhabdomyolysis, which can precipitate acute renal failure; however, this occurs less commonly than hepatic dysfunction and would be associated with myalgias and myoglobinuria. Educational objective: Common side effects of HMG-CoA reductase inhibitors (statins) include muscle and liver toxicity. Hepatic transaminases should be checked prior to initiating therapy and repeated if symptoms of hepatic injury occur. __________ References: Statins and the liver. (http://www.ncbi.nlm.nih.gov/pubmed/25939298)

A 48-Year-Old Man Comes to the Office for a Follow-Up