Total Cholesterol

Description
The term "cholesterol" usually means total cholesterol (VLDL + LDL + HDL). In recent years. total cholesterol is used less frequently that its components and triglycerides to determine risk for heart disease (Corti et al., 1997).

Cholesterol serves several functions including aiding in the synthesis of bile acids, and in the synthesis of steroid hormones.

Comorbidity may be an important factor to consider when studying cholesterol because older frail persons with a high burden of disease and low cholesterol levels are more likely to have decreased survival than are those with little or no disease and chronically low cholesterol levels (Glynn et al, 1995; Pekkanen et al., 1994; Ettinger et al., 1995).

Significance of Measurement
In middle-aged populations total cholesterol level has been shown to have a direct relation with coronary heart disease and all-cause mortality (Manolio et al., 1992). However, in older persons, it has been shown to have a U- or J-shaped relation (Anderson et al. 1987, Staessen et al., 1990) or to be inversely related or not related to risk for death (Kronmal et al., 1993; Krumholz et al., 1994).

LDL is sometimes referred to as "bad" cholesterol, because elevated levels of LDL correlate most directly with coronary heart disease, while high levels of HDL are protective.

Method of Measurement
A cholesterol test, also called lipid test and lipoprotein test, measures the amount of cholesterol and triglycerides in the blood serum.

To get accurate results for the entire lipid panel, fasting 9 to 12 hours is recommended. Total cholesterol, however, can be measured without fasting. Certain drugs and beverages such as coffee, tea, or soda may affect results.

References
· Anderson, K.M., Castelli, W.P., & Levy, D. (1987). Cholesterol and mortality. 30 years of follow-up from the Framingham study. Journal of the American Medical Association, 257, 2176-2180.
· Corti, M.C., Guralnik, J.M., Salive, M.E., Harris, T., Ferrucci, L., Glynn, R.J., et al. (1997). Clarifying the direct relation between total cholesterol levels and death from coronary heart disease in older persons. Annals of Internal Medicine, 126(10), 753-760.
· Ettinger, W.H. Jr., Harris, T., Verdery, R.B., Tracy, R., & Kouba, E. (1995). Evidence of inflammation as a cause of hypocholesterolemia in older people. Journal of the American Geriatrics Society, 43, 264-266.
· Glynn, R.J., Field, T.S., Rosner, B., Hebert, P.R., Taylor, J.O., & Hennekens, C.H. (1995). Evidence for a positive linear relation between blood pressure and mortality in elderly people. Lancet, 345, 825-829.
· Kronmal, R.A., Cain, K.C., Ye, Z., & Omenn, G.S. (1993). Total serum cholesterol levels and mortality risk as a function of age. A report based on the Framingham data. Archives of Internal Medicine, 153, 1065-1073.
· Krumholz, H.M., Seeman, T.E., Merrill, S.S., Mendes de Leon. C.F., Vaccarino, V., Silverman, D.I., et al. (1994). Lack of association between cholesterol and coronary heart disease mortality and morbidity and all-cause mortality in persons older than 70 years. Journal of the American Medical Association, 272, 1335-1340.
· Manolio, T.A., Pearson, T.A., Wenger, N.K., Barrett-Connor, E., Payne, G.H., & Harlan, W.R. (1992). Cholesterol and heart disease in older persons and women. Review of an NHLBI workshop. Annals of Epidemiology, 2(1-2), 161-176.
· Pekkanen, J., Nissinen, A., Vartiainen, E., Salonen, J.T., Punsar, S., & Karvonen, M.J. (1994). Changes in serum cholesterol level and mortality: A 30-year follow-up. American Journal of Epidemiology, 139, 155-165.
· Staessen, J., Amery, A., Birkenhager, W., Bulpitt, C., Clement, D., de Leeuw, P., et al. (1990). Is a high serum cholesterol level associated with longer survival in elderly hypertensives? Journal of Hypertension, 8, 755-761.