The purpose of the present study was to assess the clinical usefulness of direct measurement of serum low-density lipoprotein cholesterol (LDL-C) concentrations in screening for hyperlipidemia. Subjects were 842 staff of Kurume University (280 men and 562 women) who had periodic health examination. LDL-C was measured with a commercially available kit (“Cholestest LDL”), a new direct assay system for chemical measurement of LDL-C (dLDL). LDL-C was also estimated by the Freidewald calculation (fLDL). The mean value of dLDL (116.3 ± 31.3mg/dl) was 10.1% higher than that of fLDL (105.6±30.1mg/dl). There was a significantly close correlation between dLDL and fLDL (r =0. 962, p< 0.001). Based on the “Guidelines for treatment of hyperlipidemia” by the Japan Atherosclerosis Society, indication for medical treatment of hyperlipidemia by dLDL and by totalcholesterol (TC) were compared. When the criteria of dLDL≥160mg/dl or TC≥240mg/dl were used in 418 subjects who had no coronary risk factors. 25 subjects (6.0%) showed dLDL_≥160mg/dl. Of these, 6 subjects (1.4%) showed TC < 240mg/dl. Twenty-four subjects (5.8%) showed TC≥240mg/dl. Of these, 5 subjects (1.2%) showed dLDL<160mg/dl. The number of subjects considered as indication for medical treatment by dLDL was comparable to the number of those by TC. When the criteria of dLDL _≥140mg/dl or TC≥220mg/dl were used in 424 subjects who had one or more coronary risk factors, 119 subjects (28.0%) showed dLDL ≥140mg/dl. Of these, 40 subjects (9.4%) showed TC <220 mg/dl. Ninety-seven subjects (22.8%) showed TC ≥220mg/dl Of these, 18 subjects (4.2%) showed dLDL<140mg/dl. The number of subjects considered as indication for medical treatment by dLDL was greater than the number of those by TC. In conclusion, to screen subjects for hyperlipidemia using dLDL measurement in periodic health examination, the appropriate standard level of dLDL are needed for diagnosing hyperlipidemia and initiating medical therapy.
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