Why is my LDL missing?

Because triglycerides above 400 mg/dL make the Friedewald estimate invalid. A directly measured LDL is needed there, and this page will use one if you enter it.

Health & Fitnessclinical

Cholesterol Ratio Calculator

Cholesterol ratios and the Friedewald LDL estimate, with non-HDL alongside because it needs no estimation and no fasting. Where triglycerides are above 400 the Friedewald estimate is invalid and this page says so instead of printing it.

Also called: ldl hdl ratio calculator, cholesterol ratio.

Total to HDL ratio

A total to HDL ratio of 4, with non-HDL cholesterol of 150 mg/dL. The LDL is estimated by Friedewald, which subtracts a fifth of the triglycerides as a stand-in for VLDL cholesterol. That fraction is an approximation and it understates LDL when triglycerides are low. Non-HDL cholesterol of 150 mg/dL counts every particle that carries cholesterol into an artery wall and needs neither fasting nor an estimate, which is why guidelines have moved toward it. Ratios summarise a panel but discard the absolute levels, and risk assessment needs age, blood pressure, smoking status, diabetes and family history alongside them.

LDL cholesterol

120

Non-HDL cholesterol

150

LDL to HDL ratio

2.4

Triglyceride to HDL ratio

How the LDL was obtained

estimated by Friedewald

On the LDL

The LDL is estimated by Friedewald, which subtracts a fifth of the triglycerides as a stand-in for VLDL cholesterol. That fraction is an approximation and it understates LDL when triglycerides are low.

On ratios

Non-HDL cholesterol of 150 mg/dL counts every particle that carries cholesterol into an artery wall and needs neither fasting nor an estimate, which is why guidelines have moved toward it. Ratios summarise a panel but discard the absolute levels, and risk assessment needs age, blood pressure, smoking status, diabetes and family history alongside them.

How this is calculated

For reference only. Verify against your clinical protocol before acting on this number.

The panel

Measure	mg/dL	mmol/L	Population band
Total cholesterol	200	5.17	200 to 239
HDL	50	1.29	40 to 59
LDL	120	3.1	100 to 159
Non-HDL	150	3.88	130 to 189
Triglycerides	150	1.69	150 to 199

Method and background

This is what the calculation gives for the numbers you entered. It is an estimate, not advice, and it knows nothing about your situation beyond those numbers. Rules for India change on a published schedule; the effective date is shown on every rule-based tool.

How this is calculated

Most lipid panels do not measure LDL. They measure total cholesterol, HDL and triglycerides, and derive LDL by subtracting HDL and one fifth of the triglycerides, that fifth standing in for the cholesterol carried in VLDL. The assumption holds in the middle of the range and breaks at the edges, which is why the estimate is not reported above 400 mg/dL of triglycerides and understates LDL when triglycerides are low. Non-HDL cholesterol, total minus HDL, avoids the estimate entirely and does not require fasting, which is why guidelines have moved toward it. Ratios summarise the panel but discard the absolute levels, so they belong alongside the raw numbers rather than in place of them.

the Friedewald estimate, which assumes a fixed ratio of triglyceride to VLDL cholesterol and fails when triglycerides are high

TC: Total cholesterol
TG: Triglycerides

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a mid-range panel

Total cholesterol: 200
HDL: 50
Triglycerides: 150
LDL, if measured directly: 0
Units: mg/dL

Total to HDL ratio4

200 - 50 - 30 by Friedewald

Open this example

high triglycerides invalidate Friedewald

Total cholesterol: 260
HDL: 40
Triglycerides: 600
LDL, if measured directly: 0
Units: mg/dL

Total to HDL ratio6.5

boundary: no LDL reported above 400 mg/dL of triglycerides, but non-HDL is unaffected

Open this example

Method and limits

What it assumes

A fasting sample, which Friedewald requires and non-HDL does not.

What it deliberately does not model

Ratios do not replace a full risk assessment, which needs age, blood pressure, smoking, diabetes and family history.
The Friedewald estimate is invalid above 400 mg/dL of triglycerides and understates LDL at low levels.
Reference bands here are population bands, not treatment thresholds for any individual.

Formula version 1.0.0 · definition 1.0.0 · India · Report a problem with this calculator

Frequently asked questions

Why is non-HDL cholesterol preferred?: Because it needs no estimation and no fasting. It counts every particle that carries cholesterol into an artery wall, and it is available on any panel without the Friedewald assumption.
Why is my LDL missing?: Because triglycerides above 400 mg/dL make the Friedewald estimate invalid. A directly measured LDL is needed there, and this page will use one if you enter it.