A search of the medical literature shows that "we can get more precise information" by measuring apolipoprotein levels, rather than cholesterol, says Dr. Goran Walldius, a senior scientist with the AstraZeneca pharmaceutical company, lead author of a paper making that proposal in the March 1 issue of The Lancet.
There's nothing in it for AstraZeneca, Walldius is quick to add. Although the company is about to market a cholesterol-lowering statin drug -- it just received approval for the drug, Crestor, in Canada and is awaiting U.S. approval -- measuring apolipoproteins rather than cholesterol wouldn't give a boost to that drug in particular, he says.
Instead, an apolipoprotein test would tell doctors more about cardiac risk and the effectiveness of treatment than current cholesterol tests, Walldius contends.
"Total cholesterol in the blood can be misleading," he says. "Now we can measure the proteins that transport cholesterol and more closely monitor a person's condition."
The American Heart Association (AHA) isn't ready to agree, however. The proposal has been raised repeatedly, and the consensus is that the evidence isn't strong enough to make a change, says Dr. Robert H. Eckel, a spokesman for the AHA.
"This review is meritorious in terms of scientific content, and in individual patients measuring apolipoprotein levels might be more valuable than measuring cholesterol," Eckel says. "But it would be premature for the American Heart Association to recommend such a change."
Apolipoprotein A transports HDL cholesterol, the "good" kind that helps keep arteries open. Apolipoprotein B transports LDL cholesterol, the "bad" kind that clogs arteries. Measuring the ratio of A to B gives a better assessment of how well a person is doing than an ordinary cholesterol test, Walldius says.
That conclusion comes from analysis of four large-scale studies that included almost 200,000 adults, he says. On the basis of those studies, "what we need to do now is to develop guidelines so that physicians know which reading is too high and which is low," he adds. "We hope they can be developed in the next few years."
The heart association "is not closing that door," Eckel says. But the studies cited by Walldius and his colleagues are well-known and their results are "not regarded as convincing enough," he says.
An apolipoprotein blood test is available, and Eckel, a professor of physiology and biophysics at the University of Colorado Health Sciences Center, says he uses it "frequently," measuring apolipoprotein B when a patient's cholesterol is normal or low but blood levels of triglycerides, another potential risk factor, are low.
But, he adds, for most patients, he sticks to the standard cholesterol test.