Context: Altered lipid profile is common in PCOS and is usually characterized by increased triglycerides and low HDL-cholesterol levels. In general population, these alterations are often associated with increase of small low density lipoproteins (LDL) in the so-called "atherogenic lipoprotein phenotype" (ALP) that determines a further increase of cardiovascular risk. In this study we evaluated the presence of ALP in the blood of women with PCOS.

Setting: Lipid studies were performed at the Division of Endocrinology of Zurich University. PCOS patients were recruited in 2 Italian Departments.

Patients: Thirty patients with PCOS (hyperandrogenism and chronic anovulation) and 24 matched controls were studied. Anthropometric data, blood glucose, serum insulin lipid profile and LDL size and subclasses were evaluated.

Results: Compared with controls, patients with PCOS had higher blood levels of insulin and triglycerides and lower HDL-cholesterol concentrations but no differences in LDL-cholesterol and total cholesterol. Patients with PCOS had smaller LDL size due to a reduction in LDL type I, with a concomitant increase in LDL types III and IV. 14 PCOS patients had increase of smaller LDL particles and it represented the second most common lipid alteration after decrease of HDL-cholesterol. However, because in this PCOS population hypertriglyceridemia was present only in 2 patients, complete ALP was relatively uncommon.

Conclusions: Increase of type III or type IV LDL subclasses is a common finding in PCOS and represents the second most common lipid alteration after HDL-Cholesterol decrease. However, in our PCOS patients, because of relatively low triglyceride levels, complete ALP is uncommon.