There is something new in the cholesterol world. It’s called “Lipoprotein little a” or Lipoprotein(a). It is abbreviated to Lp(a). Cardiologists and lipidologists (doctors who study blood fats, ie. Cholesterol) have known about it for years, but not until recently has its significance been fully understood and a specific treatment been known.
Lp(a) is type of Low Density Lipoprotein (LDL) that has attached to it apolipoprotein(a), or apo(a). This particle (Lp[a]) is directly responsible for causing hardening of the arteries and secondarily, stroke, heart attack, aortic stenosis, coronary disease, heart failure, and arterial disease in the lower extremities. It’s a bad actor! “High quality evidence supports a link between Lp(a) levels and a variety of cardiovascular outcomes….One meta-analysis showed an increased risk of coronary heart disease and heart attack…..[and]…..a 2x higher risk of ischemic stroke.” Lp(a) has its good points, too. Being a protein, it aids in wound healing through it’s natural effect.
Menopausal hormone therapy (HRT) has gotten a bad rap the past 15-20 years. The women’s health initiative study all but implied it caused breast cancer, spreading fear among millions of women who relied on estrogen replacement to prevent hot flashes, osteoporosis, vaginal dryness, and mood swings. Most women taking HRT stopped it cold turkey. After the dust settled, it was learned that only women taking combined estrogen and progesterone were at risk. What was shown later was that HRT lowered Lp(a) levels in women by 15% to 20%. It was thought that lowering Lp(a) was a good thing for preventing heart and vascular disease.
In a Harvard-based study of 114,000 post menopausal women, Lp(a) was measured. 5% of these women were on HRT, and 39% reported prior HRT use. HRT lowered Lp(a) “modest[ly].” However, even though HRT lowered Lp(a), it did not lower the risk of cardiovascular events. The risks and outcomes were the same for both women who took HRT, and for those who did not. Prior to the women’s health initiative, it was thought HRT prevented heart disease, et al., but the study clearly showed it was not protective.
The bottom line of this blog is this: Lipoprotein(a) is directly related to causing arteriosclerosis. It should be treated with drugs that specifically lower it and other harmful LDL particles. Post menopausal hormone replacement therapy, despite lowering Lp(a) levels by 20%, does not prevent heart and vascular disease and should not be prescribed for that reason.
Measurement of Lp(a) is largely done by cardiologists and lipid researchers. It’s use by primary care practitioners was not a commonplace procedure before I retired. Whether it is now I don’t know, but knowing about it is beneficial academically. However, I think if your doctor gets your total cholesterol below 200, your HDL above 40, and your LDL below 100 (below 70 if you’re diabetic), you and he are doing well. On the other hand, post menopausal women should only use HRT for the treatment of troublesome vasomotor symptoms (hot flashes, etc.) and not for anything else.
References: Honigberg MC, Tinder M, Natarajan P. Lipoprotein(a), Menopausal Hormone Therapy, and Rusk of Coronary Heart Disease in Postmenopausal Individuals. JAMA Card 2022 April 4 (JAMA Online)
Scheel P, Meyer J, Blumenthal RS, Martin SS. Lipoprotein(a) in Clinical Practice. https://www.ACC.org/latest-in-cardiology/articles/2019/07/02/08/05/lipoproteins-in-clinical-practice.
