Falsely Low Direct HDL-Cholesterol Results in a Patient with Dysbetalipoproteinemia

[摘要] Direct methods for measuring HDL-cholesterol (HDL-C) are becoming more widely used because of their labor savings and favorable performance characteristics. We investigated three methodologies for direct HDL-C measurements. All three contain an initial reagent to block measurement of cholesterol in lipoproteins other than HDL, followed by a second reagent to measure HDL-C. The performance of each of these assays has been evaluated previously (1)(2)(3)(4)(5)(6)(7)(8). All of these direct assays appear to be relatively free of common interferences; however, triglycerides >10 g/L may affect recoveries. There are minimal published data on these new direct methods with patients who have a dyslipidemia or are receiving lipid-modifying drugs. In this report, we describe a patient with type III hyperlipidemia for whom three direct HDL-C assays yielded erroneously low results compared with traditional HDL-C methods.We analyzed a specimen from a 69-year-old man, using a direct HDL-C assay, and obtained a value that was less than the 40 mg/L detection limit of the assay. The patient had no signs or symptoms such as large orange tonsils, corneal opacities, or relapsing polyneuropathy, compatible with primary hypoalphalipoproteinemia. His medical history was remarkable for chronic obstructive pulmonary disease, peripheral vascular disease, recurrent deep vein thrombosis, congestive heart failure, coronary artery disease, hypertension, and an unspecified hyperlipidemia. His current medications included aspirin, coumadin, digoxin, diltiazem, furosemide, albuterol/ipratropium inhaler, and simvastatin, a hydroxymethylglutaryl-CoA reductase inhibitor. He had consumed no alcohol for at least 1 year. A review of results for hepatic disease tests for the past 4 years revealed serum concentrations of aspartate aminotransferase, alanine aminotransferase, and total bilirubin within the appropriate reference intervals. Alkaline phosphatase values were 1.3- to 1.9-fold higher than the upper limit of normal over this same time period. Additional …

[学科分类] 过敏症与临床免疫学