Lipid Disorders

DefinitionTop

Dyslipidemias are conditions in which plasma concentrations of lipids, lipoproteins, or triglycerides are considered elevated based on the patient’s total cardiovascular disease risk.

Total cholesterol, high-density cholesterol, and triglycerides used to be measured in the fasting state after 12 to 14 hours since the last meal. New guidelines suggest that lipid measurement could be done in a nonfasting state for the purpose of risk assessment and screening, but fasting measurements should be taken while assessing the efficacy of treatment, especially in patients with elevated triglyceride levels.

Low-density lipoprotein levels are usually calculated using the Friedewald formula:

LDL-C = TC – HDL-C – (TG/5 [mg/dL] or TG/2.2 [mmol/L])

Where: LDL-C, low-density lipoprotein cholesterol; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; TG, triglyceride.

The calculations are unreliable in patients with a triglyceride level >4.6 mmol/L (400 mg/dL).

Another frequently used formula is for non–high-density lipoprotein cholesterol:

Non–HDL-C = TC – HDL-C

Where: HDL-C, high-density lipoprotein cholesterol; TC, total cholesterol.