HDL cholesterol measurement

Total blood cholesterol 200 to 239 mg/dL HDL 35 mg/dL or more and less than 2 risk factors, provide information on dietary modification, physical activity, and risk factor reduction reevaluate in 1 to 2 years, repeat total and HDL cholesterol measurements, and reinforce nutrition and physical activity education. HDL less than 35 mg/dL or at least 2 risk factors, analyze lipoprotein base further action on LDL levels. 

E300 Warnick, G.R., Lum, C. and Knopp, R.H. (1986). Kodak Ektachem HDL kit evaluated for HDL cholesterol measurements with the DT-60 instrument. Clin. Chem. 32, 1988. 

EN24 Fahey, P.J., Lott, J.A., Peet, G.M. and Crowley, L.E. (1991). Accuracy and precision of HDL cholesterol measurements using an office chemistry analyzer. J. Fam. Pract. 32, 382-386. 

FmaUy, matrix effects can influence the results, Matris effects can arise from the nature of the. sample itself or from the addition of anticoagulants or preservatives. For example, HDL cholesterol measurements can be inaccurate, and usually are more variable when obtained from lyophilized samples than from fresh or frozen sera. 

Additives including anticoagulants such as citrate and fluoride can have large osmotic effects that cause water to shift from the cells to the plasma. This dilutes the lipoprotein by 10% or more and produces erroneously low values. EDTA, traditionally the preferred anticoagulant for lipoprotein measurements, causes a slight dilution, but has been used because it also inhibits certain oxidative and other changes that can affect some lipoprotein or apofipoprotein measurements. Lipid and Hpoprotein concentrations in EDTA plasma tend to be about 3% lower than in serum, an effect that may not be readily noticeable in HDL cholesterol measurements. EDTA, however, complexes some of the Mn in the heparin-Mn method, and it has been found necessary to use a higher concentration of MnCb (0.092 mol/L, final concentration in the reaction system) when the procedure is... 

Escola-Gil, J. C., O. Jorba, J. Julve-Gil, F. Gonzalez-Sastre, J. Ordonez-Llanos, and F. Blanco-Vaca. 1999. Pitfalls of direct HDL-cholesterol measurements in mouse models of hyperlipidemia and atherosclerosis. Clinical Chemistry 45 1567-1569. 

Cholesterol is biosynthesized in the liver trans ported throughout the body to be used in a va riety of ways and returned to the liver where it serves as the biosynthetic precursor to other steroids But cholesterol is a lipid and isn t soluble in water How can it move through the blood if it doesn t dis solve in if The answer is that it doesn t dissolve but IS instead carried through the blood and tissues as part of a lipoprotein (lipid + protein = lipoprotein) The proteins that carry cholesterol from the liver are called low density lipoproteins or LDLs those that return it to the liver are the high-density lipoproteins or HDLs If too much cholesterol is being transported by LDL or too little by HDL the extra cholesterol builds up on the walls of the arteries caus mg atherosclerosis A thorough physical examination nowadays measures not only total cholesterol con centration but also the distribution between LDL and HDL cholesterol An elevated level of LDL cholesterol IS a risk factor for heart disease LDL cholesterol is bad cholesterol HDLs on the other hand remove excess cholesterol and are protective HDL cholesterol IS good cholesterol... 

Short-term evaluation of therapy for hyperlipidemia is based on response to diet and drug treatment as measured in the clinical laboratory by total cholesterol, LDL-C, HDL cholesterol, and triglycerides. 

Although both LDL and HDL are primarily cholesterol particles, most of the cholesterol measured in the blood is assodated with LDL. The normal role of LDL is to deliver cholesterol to tissues for biosynthesis. When a cell is repairing membrane or dividing, the cholesterol is required for membrane synthesis. Bile acids and salts are made from cholesterol in the liver, and many other tissues require some cholesterol for steroid synthesis. As shown in Figure 1-15-6, about 80% of LDL are picked up by hepatocytes, the remainder by peripheral tissues. ApoB-100 is the only apoprotein on LDL, and endocytosis of LDL is mediated by apoB-100 receptors (LDL receptors) clustered in areas of cell membranes lined with the protdn clathrin. 

Monitoring Pretreatment and annual exams should include blood pressure, breasts, abdomen and pelvic organs, including Papanicolaou smear. Perform preventative measures and screening, which should include total and HDL cholesterol within 5-year intervals. Advise the pathologist of OC therapy when relevant specimens are submitted. Do not prescribe for more than 1 year without another physical exam. Lipid disorders Closely follow women taking OCs who are being treated for hyperlipidemias. 

Standard lipid screening to obtain a cholesterol profile for the risk of cardiovascular disease routinely reports total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides. Cholesterol values are reported in milligrams per deciliter of blood (mg/dL). Different organizations have made recommendations for normal cholesterol levels, but these must be interpreted carefully, as they are contingent on other risk conditions. For example, the recommendations for smokers or those with a family history of heart disease will be lower for someone without these conditions. The National Center for Cholesterol Education (NCEP) endorsed by the American Heart Association believes that LDL is the primary cholesterol component to determine therapy. LDL cholesterol accounts for 60—70% of blood serum cholesterol. An LDL less than 160 mg/dL is recommended for individuals with no more than one risk factor and less than 100 mg/dL for individuals with coronary heart disease. NCEP classifies HDL, which comprises between 20% and 30% of blood cholesterol, below 40 mg/dL as low. Triglycerides are an indirect measure of VLDL cholesterol. The NCEP considers a normal triglyceride level as less than 150 mg/dL. 

In this experiment, two cholesterol measurements will be made (1) total serum cholesterol and (2) HDL serum cholesterol, the amount of cholesterol associated with the HDL fraction. The following relationship leads to an estimate of LDL (Equation El 1.7). 

B 9. Explain the principles behind the use of the phosphotungstate reagent to measure HDL-cholesterol. 

Hypolipoproteinemia is likely to be a rare adverse effect. The measurement of HDL cholesterol and triglycerides before and after staring thiazolidinedione therapy will allow its detection. On withdrawing therapy concentrations return to normal. This effect may be specific to rosiglitazone, as it is becoming apparent that the PPAR-y agonists vary in their effects. 

Low HDL cholesterol (<40 mg/dL), confirmed by multiple measurements Negative risk factors... 

In a study from the Mayo Clinic (M4), a group of male patients undergoing diagnostic coronary angiography for chest pain or suspected coronary artery disease had plasma cholesterol and triglyceride, HDL cholesterol, and apoA-I concentrations measured. Whereas HDL cholesterol discriminated to some extent between those with and those without important coronary artery disease (and total cholesterol and triglyceride did not discriminate at all), apoA-I levels provided an almost perfect prediction of obstructive coronary artery disease. Some caveats on the interpretation of apoA-I levels in this and other studies have been noted by Blackburn (B34). 

The manganese content of the basal diets and of urine, feces and whole blood was measured using a Varian Techtron Atomic Absorption Spectrophotometer Model 1275. Urine samples were read directly using a graphite furnace attachment (Model GTA-95). Fecal composites were analyzed for fat content (13). Serum total cholesterol and HDL-cholesterol were enzymatically assayed (12,14). 

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