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Jornal Brasileiro de Patologia e Medicina Laboratorial
On-line version ISSN 1678-4774
SEKI, Mario et al. Determination of lipid and lipoprotein classification levels in school children from ten to nineteen years old from the city of Maracaí, SP, Brazil. J. Bras. Patol. Med. Lab. [online]. 2003, vol.39, n.4, pp. 309-316. ISSN 1678-4774. http://dx.doi.org/10.1590/S1676-24442003000400008.
BACKGROUND: Epidemiological studies on lipid profiles in young people offer data for the prevention of atherosclerotic morbidities and the reduction of high mortality rate due to cardiovascular disease. However, the Brazilian authors make use of classification levels from other countries, usually the American standards. The III DBSD (initials in Portuguese for Brazilin Guidelines on Dyslipidemias, 2001), have also adopted this practice, thus recommending the use of levels from the National Cholesterol Education Program (NCEP) (USA, 1992). This practice does not take into account the socioeconomic and ethnic differences, physical makeup and food choices of the Brazilian population. It may induce potential bias and incorrect assessment of dyslipidemias in our region. OBJECTIVE: to establish classification level for triglycerides (TG), total cholesterol (TC), LDL-cholesterol (LDL-c), HDL-cholesterol (HDL-c), non-high-density lipoprotein cholesterol (non-HDL-c) in students of both sexes from the city of Maracai (SP), in the ten- to nineteen-year-old age group. METHODS: cross-sectional design. A total of 1,371 male and female students, in the ten- to nineteen-year-old age range of eight public schools and one private school, were evaluated between March 25th and October 8th 2002. The tests for TC and TG were conducted with enzymatic reactions, Johnson & Johnson kits, dry chemistry methodology, and Vitros 750 auto-analyzer. The enzymatic dosage of HDL-c was preceded by the precipitation of LDL-c and VLDL-c present in the serum through the use of a magnetically responsive reagent containing dextran sulphate and magnesium chloride (Johnson & Johnson). The LDL-c levels were determined through the Friedewald equation for TG lower than 400.0 mg/dL: LDL-c = TC - HDL-c - TG/5; for results greater than this, the serum was precipitated with polyvinyl sulfate dissolved in poliethylenoglycol at 25%, pH 6.7 and later determined with Merck CHOD-PAP kits and photometric reading in the model E-225 CELM equipment. Non-HDL-c was calculated on CT - HDL-c. RESULTS: Excluded cases amounted to 255. A total of 1,116 cases were tested - 509 males and 607 females. The classification levels that were obtained in the studied samples differ from the values recommended by the III DBSD. The largest variations were found in the results at the 75th and 95th percentiles for LDL-c, respectively, 93 mg/dl (a -15.5% variation) and 118.2 mg/dl (a -9.1% variation). DISCUSSION: the classification levels transcribed from the NCEP may not apply to certain Brazilian areas and their indiscriminate use may lead to bias. CONCLUSION: the classification levels for TC, LDL-c, and HDL-c established for students of both sexes from the city of Maracaí, in the ten-to nineteen-year-old age group proved to be in disagreement with recommended values in the III DBSD. Similar investigations in other areas have been suggested in order to establish adequate classification levels for the Brazilian population in this age group.
Keywords : Lipid profile; Normal range; Youth; Cholesterol; Triglycerides; Dyslipidemia; Non-high-density lipoprotein cholesterol.