High density lipoproteins (HDL) are particles that carry cholesterol in the blood.
(hdl-c) is a general estimate of HDL levels. Hdl is also measured as HDL particle number (hdl-p). Due to variability of cholesterol carried in hdl, hdl-c & hdl-p values often disagree. When this happens, heart
disease risk tracks with low hdl-p (< 30 umol/l) regardless of high or low hdl-c levels.