Cholesterol/HDL ratio

UK laboratories print a variety of upper limits, most often 4.0, with some using 5.0 or 6.0; it has no units because it is one number divided by another.

This is the total cholesterol divided by the HDL ('good') cholesterol. A single figure that combines the two is a quick way of seeing how much of the cholesterol in the blood is being carried in the protective HDL particles compared with the rest. A lower ratio means a larger share is in HDL.

It is printed on most UK lipid profiles and is one of the figures doctors use when looking at heart and circulation health in the general population.

• A higher total cholesterol
• A lower HDL cholesterol, for example with smoking, being overweight or type 2 diabetes
• An underactive thyroid
• Some medicines, including anabolic steroids

• Cholesterol-lowering medicines such as statins
• Regular exercise, which raises HDL
• Weight loss and changes in diet
• Being female, in the general population

• Because it is a ratio, a small change in HDL moves it more than the same change in total cholesterol
• A recent illness lowers both numbers and can shift the ratio either way
• Laboratories round the two inputs differently

No fasting needed. It is calculated from two other results on the same report, so it carries the same day-to-day variation as they do.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.