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Secondary causes of hyperlipidemia
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A 34-year-old woman was sent to me because of hyperlipidemia refractory to lipid-lowering therapy. She had an LDL of 192 mg/dL. Interestingly, an LDL four years earlier was only 120 mg/dL. There was no family history of premature cardiovascular disease. Her primary care physician prescribed atorvastatin (Lipitor, Pfizer) 20 mg per day. A follow-up LDL was only 188 mg/dL. The physician recommended increasing the atorvastatin. The patient had muscle aches, even before therapy, and now they were worse. She did not want to take the statin any longer. She requested a second opinion.
The most common reasons we see patients in lipid clinic are side effects from antihyperlipidemic therapy and/or lack of response to therapy. Before beginning or making any changes to therapy, it is essential to evaluate for secondary causes of dyslipidemia. I remind medical students and residents to think of the four D’s when considering possible secondary causes of dyslipidemia.
- Diet: excessive intake of saturated fat and/or calories, alcohol consumption, anorexia
- Drugs: diuretics, beta-blockers, cyclosporine, estrogen, glucocorticoids, anabolic steroids, retinoids, protease inhibitors
- Disease: chronic liver disease, primary biliary cirrhosis, chronic renal failure, nephrotic syndrome, Cushing’s syndrome, systemic lupus erythematosus
- Dysmetabolism: hypothyroidism, diabetes, obesity, insulin resistance
As part of our screening, I obtained a thyroid-stimulating hormone level, which was 12.0 uIU/mL. With treatment of hypothyroidism, the LDL cholesterol decreased to 112 mg/dL — on no lipid-lowering medication. The muscle aches disappeared.
This woman and her husband had been contemplating starting a family in the near future. Had the hypothyroidism not been identified and treated, it could have had negative consequences on the development of the baby. In addition, statins are contraindicated in pregnancy. For this reason, statins should be used with caution in women of childbearing age, whether they are planning pregnancy or not.
It is easy to fall into the trap of treating numbers and not patients. Laboratory studies are useful tools but we must remember they are only tools. An LDL of over 190 mg/dL is very high and should not be ignored. Nevertheless, secondary causes are more common than primary dyslipidemia and must not be forgotten. There should be no rush to begin pharmacotherapy, particularly in a low-risk individual, until secondary causes have been ruled out and dietary/lifestyle modification tried.