When should low HDL cholesterol levels not be a worry?

Low HDL cholesterol does not increase the risk of coronary heart disease when LDL cholesterol and triglyceride levels are normal, in an analysis from the Framingham Offspring Study.

In this study, “isolated HDL levels lower than the median are associated with low risk of CHD. These data suggest that isolated low HDL may not be an atherogenic phenotype,” said at the annual meeting of the American College of Cardiology.

It’s known that low HDL is linked to increased CHD risk, but the risk in patients with isolated low HDL hasn’t been well studied. Yet low HDL together with an LDL below 100 mg/dL and a triglyceride level below 100mg/dL is not a rare combination. It represented 7.4 percent of all study patients with low HDL, as defined by a level below the median, meaning less than 42 mg/dL in men and 54 mg/dL in women, noted by the professor of medicine, epidemiology, and preventive medicine preventive cardiology at the University of Maryland, Baltimore.

Reported on 3,560 adults in the Framingham Offspring Study with baseline lipid measurements recorded in 1987-1991. During a mean follow-up of 18 years, the incidence of newly diagnosed CHD was low in participants with isolated low HDL: just 5 percent. That was similar to the 4 percent incidence in subjects with the above average HDL and low LDL and triglycerides. In contrast, when low HDL was present in subjects with higher LDL and or/ triglycerides, the incidence of CHD was higher. So was the relative risk of CHD in a multi variate analysis after adjustment for age, sex, smoking status, diabetes and hypertension.

When low HDL was present in combination with an LDL greater than 130 mg/dL along with triglycerides elevated above cut points of 150 and 200 mg/dL, the incident CHD rates climbed to 20 percent -25 percent, with adjusted hazard ratios of 1.7 -2, compared with the risk in subjects with isolated low HDL.