HDL cholesterol too low? What your value means as a woman

Your HDL result is the amount of cholesterol carried by the smallest and densest lipoproteins in your blood, in millimoles per litre (mmol/l). Those particles collect cholesterol from your tissues and from the artery wall and deliver it to the liver. The test does not count how many of those particles you have and does not measure how well they do their job; it only weighs the cargo.

The limits on this page are the risk bands of the NVKC, the Dutch society of clinical chemists, and they apply to women and men alike: below 1.04 mmol/l a higher cardiovascular risk, 1.04 to 1.55 a moderate risk, above 1.55 a low risk. No upper limit is given. The laboratory prints its own range on the result itself, 0.9 to 1.7 mmol/l in our case, and that is a lab convention.

What is different for women is the starting point. Oestrogen stimulates production of the main HDL protein and slows the breakdown of HDL particles, which leaves women on average roughly 0.2 to 0.3 mmol/l higher than men from puberty onwards. So the same 1.1 mmol/l falls in the same moderate band for you and your partner, but sits further below the average for your sex in you. And because oestrogen is the engine behind that difference, your HDL moves with anything that changes your oestrogen level: hormonal contraception, pregnancy, hormone therapy and the menopausal transition all leave traces in this value. That makes your HDL more informative than a man's, but also easier to misread without knowing which life stage you are in and which agents you use.

One relationship belongs with that. HDL moves inversely with triglycerides. A transfer protein swaps cholesterol out of your HDL particles in exchange for triglycerides from the fat-rich particles; the loaded HDL particle then loses cholesterol and is cleared faster. A low HDL is therefore rarely a stand-alone problem, but almost always the shadow of a raised triglyceride value and of the insulin sensitivity behind it. So never read your HDL without your triglycerides and your LDL beside it. You do not need to fast; HDL barely shifts after a meal.

Most information about cholesterol is written with a male average in mind. With HDL that shows immediately, because this is the value where the difference between women and men is largest and where your hormonal life stage weighs most heavily.

The average is not the same number. The limits are the same for everyone, but you start from a higher point: oestrogen keeps your HDL on average 0.2 to 0.3 mmol/l higher than a man's. In practice that means the following. If you and your partner both come out at 1.1 mmol/l, you are both in the moderate band, but his result sits close to the male average and yours clearly below the female average. For you it is therefore a stronger signal to look at the triglycerides and the waistline, even though the same number is printed.

Menopause does something other than what you have probably read. The persistent story is that HDL falls during the transition and that risk rises as a result. That is not correct. In long-running research following women through the menopausal transition, the HDL concentration stays flat or even rises slightly. What does change is the quality of the particles: they get smaller, take on more triglyceride and become less good at removing cholesterol from the artery wall. So the number holds while the function declines, and an HDL that climbs across the transition even went together in that research with more arterial change. For you that means: a stable or rising HDL around menopause is no reassurance, and a conversation about your LDL, your non-HDL cholesterol and your ApoB is more useful in that phase than a conversation about your HDL.

What does measurably worsen around menopause are the other lipids. Total cholesterol, LDL and ApoB rise measurably around the final menstrual period, and that is the change that counts. Women who notice their cholesterol values worsening without anything changing in their lifestyle are experiencing real physiology and are not imagining it.

And you can barely raise it, and higher is not better without limit. Drugs that raised HDL substantially did not reduce cardiovascular events, and people who naturally carry a genetic variant for a higher HDL do not have a lower risk because of it. In large Danish population research the lowest mortality in women sat around 2.4 mmol/l and climbed again from roughly 3.5 mmol/l. The Dutch GP standard therefore sets no target for HDL. HDL is a reflection of your metabolism: a low HDL tells you something else is going on, usually raised triglycerides, abdominal fat or reduced insulin sensitivity, and those are the factors that carry the risk.

HDL belongs in a full lipid profile, together with total cholesterol, LDL and triglycerides. Drawn on its own the value says too little.

The day of your cycle barely matters for HDL. Unlike oestradiol or the other cycle hormones, a lipid profile does not need to be drawn on a particular day; the variation across the cycle is small compared with the difference between life stages. Fasting is not required either, although your doctor may ask for a fasting repeat if your triglycerides come out high.

What does count is the life stage you are in when you test. During pregnancy your total cholesterol, your HDL and your triglycerides all rise substantially, as normal physiology, and a lipid profile from that period cannot be compared with the ordinary limits; wait to interpret until roughly six to eight weeks after delivery, and longer if you are breastfeeding. A combined pill containing oestrogen makes HDL rise, a higher number from the pill and not from a better metabolism, while contraception with an androgenic progestogen blunts or reverses that rise; that depends on the type of pill and not on you. Oral oestrogen therapy in menopause raises HDL because the hormone passes through the liver first, and oestrogen through the skin barely does, so an unchanged HDL is normal there. In the menopausal transition itself the value stays flat or rises slightly while the particles get smaller; the number hides a loss of function there. And high triglycerides press HDL down, in which case you treat the triglycerides and not the HDL.

So always report which hormonal agents you use, because without that information the result cannot be placed. Also postpone testing until a few weeks after an infection or an operation, because the whole profile dips temporarily then. A single measurement is a snapshot; have an abnormal result repeated before drawing conclusions from it.