HDL cholesterol

Also known as HDL, good cholesterol

lipid class · no single molecular formula

LOINC 2085-9 code verified serum mg/dL

What this substance is

HDL is a particle of protein and many lipids, not a compound. The test measures the cholesterol carried inside HDL particles, so the molecule counted is cholesterol.

Each molecule is drawn from ChEBI's curated 2D drawing, accepted only after its InChIKey, formula and charge matched the ChEBI release. Atom diagrams are checked against the NIST Atomic Spectra Database.

3D model · cholesterol

What is counted: cholesterol carried in HDL particles. Generated by RDKit from ChEBI's verified structure, and accepted only because its own 3D geometry reproduces ChEBI's InChIKey. A flexible molecule takes many shapes; this is one low-energy one. Drag to rotate, scroll to zoom.

Reference ranges

Checking your own result against this range needs the running application; this is a static copy. Nothing you type anywhere in Empeiria is ever sent to a server.

all

normal range · mg/dL

Applies to	Normal	Optimal	Critical
all	≥ 40 mg/dL	—	—

guideline limit ATP III Guidelines At-A-Glance Quick Desk Reference, National Cholesterol Education Program (NHLBI) cited · not yet checked by a person

How it is measured

In practice

HDL is checked as part of a cholesterol blood test. A health worker takes a small blood sample from a vein in your arm. You may need to fast for 9 to 12 hours, so the test is often done in the morning.

Measured within the lipid panel on a venous blood sample by venipuncture. A 9-12 hour fast may be requested, hence morning testing. HDL is one of the inputs (with total cholesterol and triglycerides) from which LDL may be estimated.

Before the test

Fast (no food or drink) for 9 to 12 hours if your provider asks.

Where: laboratory

Source: Cholesterol Levels, MedlinePlus (U.S. National Library of Medicine) cited · not yet checked by a person

In the lab

enzymatic colorimetric

Direct (homogeneous) HDL-cholesterol

A chemical first "switches off" the other fat-carrying particles in the blood. Then enzymes react only with cholesterol in HDL and make a colour, and the machine measures how strong the colour is.

Non-HDL (apoB-containing) lipoproteins are blocked by a reagent so they do not react, and cholesterol in HDL is then measured enzymatically with cholesterol esterase and cholesterol oxidase, with no separation step.

Read by: Absorbance (colour) of the enzymatic reaction product

What can throw it off

dyslipidaemic samples (larger direct-method bias)

Why labs disagree: Most laboratories now use homogeneous direct HDL-C reagents instead of the older precipitation methods. In one study, five of eight direct assays met accuracy goals in people with normal lipids, but all failed in samples from people with cardiovascular disease or dyslipidaemia. Even a method calibrated to a reference can drift: a national health survey's laboratory showed positive biases of 2.85% to 9.40% in external quality checks over several years, and its results had to be corrected.

Sources: Calibration of High-Density Lipoprotein Cholesterol Values From the Korea National Health and Nutrition Examination Survey Data, 2008 to 2015 (Ann Lab Med, PMC open access); NHANES 2005-2006 Laboratory Procedure Manual: HDL-Cholesterol, Hitachi 912 (CDC/NCHS) cited · not yet checked by a person

What it reports on

liver synthesized by
The liver and intestine make apoA-I, the main HDL protein, and HDL brings cholesterol back to the liver for removal.
circulatory system transported by
HDL carries cholesterol through the blood from the body back to the liver.

Associated symptoms

Conditions this marker features in

When low

low A cluster of risks that travel together · defining
One of the five criteria (three are needed): HDL below 40 mg/dL in men or below 50 mg/dL in women. These are criteria for a risk-factor cluster, not a diagnosis of a single disease.
low Fatty liver · defining
One of the five cardiometabolic criteria (any one is enough, with fat in the liver): HDL 40 mg/dL or lower in men, 50 mg/dL or lower in women, or lipid-lowering treatment.
low Unhealthy cholesterol levels · defining
Classification, not a single diagnostic test: in the NCEP ATP III scheme an HDL below 40 mg/dL is 'low'.
low Blood sugar higher than normal, but not diabetes · supportive
Low HDL often goes with prediabetes, and an HDL below 35 mg/dL is one reason the ADA gives for testing adults with overweight.
low Type 2 diabetes · supportive
Low HDL with high triglycerides is the most common lipid pattern in type 2 diabetes; a lipid panel is checked at diagnosis.

Ordered as part of

lipid · metabolic_risk