Protein may predict heart problems.

Low blood concentrations of a small protein called adiponectin can signal high risk of heart disease, a study finds. Scientists suggest that the molecule might join the growing list of previously obscure compounds that might help doctors detect signs of potential cardiac troubles in otherwise healthy individuals.

Tobias Pischon and his colleagues at the Harvard School of Public Health in Boston assessed adiponectin concentrations in blood samples taken in 1994 from 18,130 men who were free of heart disease. After 6 years, 266 of them had either suffered a nonfatal heart attack or died of heart disease.

The men who had initially registered the highest concentrations of adiponectin were only one-third as likely as those with the lowest concentrations to have had a heart attack. The correlation held up even when researchers accounted for the men's physical activity, family history, hypertension, alcohol consumption, and other factors.

Meanwhile, another team of researchers studying 178 postmenopausal women found that low adiponectin coincided with excess weight, a factor that increases risk of heart problems. Lewis Kuller of the University of Pittsburgh reported that lean women had adiponectin concentrations of 18.7 micrograms per milliliter of blood, whereas heavier women averaged concentrations of only 14.1 [mu]g/ml.

The women with low adiponectin also tended to have small low-density lipoprotein molecules, the specific form of the so-called bad cholesterol thought to pose the greatest risk for heart disease.

The mechanism by which fat cells turn on adiponectin secretion is unclear, as is the compound's role in the body. N.S.