May 7, 2025

Lipoprotein A (also called Lp(a)/”L-p-little-a”), Warde test code LPA, has changed units from mg/dL to nmol/L. This change was instituted in response to requests from cardiologists, based on cardiac risk guidelines that follow nmol/L cutoffs. Since lipoprotein particle sizes vary, there is not a precise conversion factor for translating milligrams to nanomoles; Warde instituted this change by re-verifying the assay against standards measured in nmol/L. Going forward, users will see a reference range for flagging as normal/abnormal (normal defined as less than or equal to 75 nmol/L, based on population distribution), as well as text comments delineating recommendations from three professional organizations:

≥125 nmol/L is an accepted target in American College of Cardiology/American Heart Association (ACC/AHA) guidelines.

<75 nmol/L is considered normal, 50-125 nmol/L intermediate, and >125 nmol/L abnormal in the European Atherosclerotic Society (EAS) consensus statement.

>100 nmol/L is accepted as a risk-enhancing cutoff in the National Lipid Association (NLA) scientific statement.

It may be helpful to know, when comparing results with different units, that 2.5 is considered a rough conversion factor (1 mg/dL of Lp(a) to 2.5 nmol/L). The CDC states that high levels of Lp(a) increases the likelihood of heart attack, stroke, or aortic stenosis, especially in the setting of familial hypercholesterolemia or signs of coronary heart disease. Elevated Lp(a) has a strong genetic component, and is considered an independent risk factor for atherosclerotic cardiovascular disease. As such, serial measurement (routine repetition of Lp(a) quantification) is not a useful practice. Patients already taking statins may exhibit higher Lp(a) levels than what would have been measured at baseline; this phenomenon is relevant in interpretation of results, but it should be noted that the effect of statins on measured Lp(a) does not change the recommendation that high LDL-cholesterol levels be treated with statins or other appropriate interventions. Additional information can be found at the sources listed below.

https://www.cdc.gov/heart-disease-family-history/about/about-lipoprotein-a.html

https://www.acc.org/Latest-in-Cardiology/Articles/2023/09/19/10/54/An-Update-on-Lipoprotein-a