LDL/HDL Ratio: A Key Cholesterol Balance

The LDL/HDL ratio is nothing more than your LDL cholesterol divided by your HDL cholesterol. The lab measures those two, divides one by the other and prints the result. No extra tube of blood goes in, and no extra information comes out: everything in the ratio was already somewhere else on your report.

That sounds harmless, but it leaves the ratio vulnerable in two ways that bite precisely in your population.

The first is the calculation error the ratio inherits. In most laboratories your LDL is not measured but calculated, with the Friedewald formula: total cholesterol minus HDL minus triglycerides divided by 2.2. With high triglycerides or a non-fasting sample that assumption no longer holds. The calculated LDL then comes out too low, so your ratio looks better than reality. A blood draw after a carbohydrate-heavy loading phase, or simply too soon after your last meal, is enough to produce that effect. The cholesterol/HDL ratio does not have this problem, because it uses two directly measured values.

The second is what is missing. VLDL particles and the remnants left over from them do carry cholesterol into the artery wall, but they appear in neither the numerator nor the denominator. Anyone with high triglycerides and reduced insulin sensitivity sees none of that reflected in this number. Non-HDL cholesterol does count those particles.

This is not the same number as the cholesterol ratio. The cholesterol/HDL ratio uses total cholesterol in the numerator and has an upper limit around 5. This ratio uses only the LDL and sits around 3. They share a name and a denominator, and nothing else: do not confuse them.

If you track your blood values to perform better and recover better, this is the number you have least use for. That is not a figure of speech, it is where the guidelines stand. Both the European ESC/EAS guideline and the Dutch CVRM standard set targets on LDL cholesterol, with non-HDL cholesterol and ApoB as secondary goals. For the LDL/HDL ratio, no guideline sets a goal at all.

And there is an arithmetic illusion built into it. An LDL of 3.0 mmol/l with an HDL of 1.0 mmol/l gives a ratio of 3.0. An LDL of 4.5 mmol/l with an HDL of 1.5 mmol/l also gives exactly 3.0. Identical number, and yet the second person carries fifty percent more atherogenic cholesterol. It is that absolute LDL which accumulates in the artery wall, not the proportion. A ratio that looks good therefore says nothing until you place the individual values next to it.

For athletes there is a trap of their own on top of that. Regular endurance training raises HDL slightly, while LDL often barely moves. The ratio falls, your result looks better, and the amount of harmful cholesterol has stayed exactly the same. The number flatters you, and that feels like progress when nothing has been won.

There is one situation in which this ratio is in fact sharper than its components: the use of anabolic androgenic steroids. Androgens push HDL down substantially and drive LDL up. Both halves of the fraction therefore move the wrong way at once, which makes the ratio swing harder and earlier than the LDL or the HDL on their own. As a within-person trend, measured under the same conditions, that is usable information, and it is the only place where this ratio earns its spot on your report. It is not a reason to dose or change anything yourself: discuss it with a doctor.

For everything else: let non-HDL or ApoB carry more weight. Non-HDL needs no formula, does not break at high triglycerides and requires no fasting. ApoB counts the number of harmful particles instead of their cargo. Both say something this ratio cannot.

You do not order this ratio separately. It falls out of a lipid panel automatically once the LDL and the HDL have been determined, so the real question is how you take that panel.

Fasting counts for more here than for most lipids. Total cholesterol and HDL barely change after a meal, but triglycerides do, and your LDL is calculated from them. So test fasted, and avoid a draw straight after a carbohydrate-heavy loading phase or a period of heavy drinking. Above roughly 4.5 mmol/l of triglycerides the formula is no longer valid and the ratio says nothing at all.

Also take your training load into account. A long endurance session can temporarily lower triglycerides and slightly raise HDL, for up to a few days afterwards. If you want to compare values between two training blocks, always test at a comparable point in the week and at the same laboratory. And wait a few weeks after an infection, surgery or a significant injury: cholesterol falls temporarily in that period.

A newly abnormal result deserves a search for an underlying cause before you start adjusting your diet. An underactive thyroid raises LDL and is often missed, so a TSH belongs in the workup.

Have every result assessed by a doctor, together with your individual values and your full risk profile.