CardioSmart: Lp(a) Check May Not Be Helpful in Women Taking Hormone Replacement Therapy

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Lp(a) Check May Not Be Helpful in Women Taking Hormone Replacement Therapy

By Paula Rasich
Reviewed by Elizabeth Klodas, MD, FACC

(CardioSmart) According to a new study, women who get a Lipoprotein(a), Lp(a), test while on hormone replacement therapy (HRT) may not be getting a true picture of their heart risk.

Lp(a) is a variation of LDL (bad) cholesterol that also promotes blood clotting. Past studies indicate that very high blood levels of Lp(a) increase your odds of heart disease.

Having some of this type of cholesterol in your bloodstream is harmless, but abnormal levels can raise your risk for clogged arteries and heart attacks. The Lp(a) level is checked with a blood test.

Jacqueline Suk Danik, MD, MPH, and colleagues from Brigham and Women’s Hospital and Harvard Medical School analyzed data from the Women’s Health Study, a 10-year trial involving more than 27,000 healthy women, aged 45 and older.

Suk Danik and researchers compared blood samples of over 12,000 women using HRT with a similar group of nearly 16,000 women not on HRT. Consistent with previous findings, they found that Lp(a) levels were lower in women using HRT. In the group not using HRT, women with the highest levels of Lp(a) had nearly a twofold increase in their risk of cardiovascular disease, compared to those with the lowest levels. In contrast, women using HRT demonstrated no increase in cardiovascular risk, even if Lp(a) levels were high.

The investigators reason that the women in the study who were taking HRT may have led an overall healthier lifestyle, offsetting their cardiovascular risk. Regardless, the ability to predict risk using Lp(a) was significantly weakened in women on hormone replacement.

So what does this mean for women using HRT to ease menopausal symptoms? “If a clinician is going to check Lp(a) in a patient who has a strong family history of cardiovascular disease, and is going to use that measure to guide medical therapy, then Lp(a) levels should be rechecked when the woman is not on HRT,” says Suk Danik. “There seems to be an interaction between HRT and Lp(a) on risk of cardiovascular disease, and the Lp(a) value may be [misleading] when a woman is on HRT.”

The study is published in the July 8th issue of the Journal of the American College of Cardiology.

Sources:

Suk Danik J et al. Lipoprotein(a), Hormone Replacement Therapy, and Risk of Future Cardiovascular events. Journal of the American College of Cardiology, 2008.

Berglund L and Anuurad E. Role of Lipoprotein (a) in Cardiovascular Disease. Editorial Commentary. Journal of the American College of Cardiology, 2008.

Jacqueline Suk Danik, MD, MPH, Instructor of Medicine at Harvard Medical School; Cardiologist, Brigham and Women’s Hospital in Boston, MA.

Please note that the content on CardioSmart attempts to define practices that meet the needs of most patients in most circumstances. However, everyone is unique, and the extent to which the information applies specifically to you should be a key point of discussion between you and your cardiologist or health care provider. The ultimate judgment regarding your care must be made by you and your healthcare provider together, in light of circumstances specific to you as a patient.