Analytical and clinical evaluation of two homogeneous assays for LDL-cholesterol in hyperlipidemic patients.

BACKGROUND: LDL-cholesterol (LDL-C) concentrations are the primary basis for treatment guidelines established for hyperlipidemic patients. LDL-C concentrations are commonly monitored by means of the Friedewald formula, which provides a relative estimation of LDL-C concentration when the triglyceride concentration is <2000 mg/L and there are no abnormal lipids. The Friedewald formula has several limitations and may not meet the current total error requirement of <12% in LDL-C measurements. METHODS: We evaluated the analytical and clinical performance of two direct methods (Roche and Wako) by analyzing 313 fresh serum samples obtained from dyslipidemic patients in a lipid clinic and comparing them with modified beta-quantification. RESULTS: Both homogeneous assays displayed excellent precision (CV <2%). The Roche method showed a mean total error of 7.72%, and the Wako method showed a mean total error of 4.46% over a wide range of LDL-C concentrations. The Roche method correlated highly with the modified beta-quantification assay (r = 0.929; y = 1.052x - 168 mg/L; n = 166) and showed a bias of -4. 5% as a result of the assigned standard value. The Wako method also correlated highly with beta-quantification (r = 0.966; y = 0.9125x + 104.8 mg/L; n = 145) without significant bias. The Roche method correctly classified 97% of patients with triglycerides <2000 mg/L, 75% of patients with type IIb hyperlipemia (HPL), and 84% of patients with type IV HPL based on the cutpoints of 1300 and 1600 mg/L, compared with 98%, 78.4%, and 89%, respectively, for the Wako method. In dysbetalipoproteinemic patients, both methods have a 30% mean positive bias compared with beta-quantification. CONCLUSIONS: Both direct methods can be a useful alternative when ultracentrifugation is not available for the diagnosis and control of lipid-lowering medication for patients with mixed HPL, but not for patients with type III hyperlipidemia.

[Intra-abdominal tumor in a young man]. / Tumor desmoide intraabdominal en un varón joven.

Desmoid tumor is a rare neoplasm with extra-abdominal location and female predilection. Anatomopatological analysis is necessary to establish the diagnosis unequivocally, but Magnetic Resonance is the no aggressive method with the best sensitivity and specificity. Surgical resection is the elective treatment yet, and prognosis is not so good as it could be expected in a benign tumor. We report a young male case without polyposis coli antecedents. When he was attended, he related only an abdominal bulk with no other symptom. An intra-abdominal mass 32 cm length per 25 cm width consistent with desmoid tumor was finally resected.

[ANCA-associated lung hemorrhage]. / Hemorragia pulmonar asociada a ANCA.

Pulmonary haemorrhage is a severe complication of small-vessel vasculitis associated with antineutrophil cytoplasm antibodies (ANCA). The main pathologic finding is a pauci-immune capillaritis, although occasionally this lesion is not present. The differential diagnosis includes different diseases and therefore ANCA measurement is important. Two cases of pulmonary haemorrhage associated with ANCA in patients with a clinical picture suggesting small-vessel vasculitis is here reported and a review of the literature is made.