[Relation between intermediate troponin T values and diagnosis of cardiac disease]. / Relación de los valores intermedios de troponina T con el diagnóstico de enfermedad cardíaca.

BACKGROUND AND OBJECTIVE: Troponins are useful tools in management of patients with acute coronary syndrome (ACS). Small increases do not guarantee a desirable precision (CV < 10%) and there is a "grey zone" between 99 percentile and clinical cut off. Our objective was to evaluate if "grey zone" troponin values reflect heart damage or they are only "analyzer noise". PATIENTS AND METHOD: Final diagnoses of patients with "grey zone" values attended during 2001 and 2002 were reviewed (group Tn). Control group (Cn): patients with negative values (four months randomly chosen during the same period). Admitted patients were classified in: A, ACS; B, non ischemic heart disease, and C, non heart disease. RESULTS: Tn group (n = 521): admitted, 330 (63.3%); A (53.9%), B (30.9%), C (15.2%). Cn group (n = 652): admitted, 156 (23.9%); A (41%), B (24.4%), C (34.6%). Odds ratio for admittance (Tn vs Cn) was 4.82 (95% CI, 3.68-6.31); OR for diagnosis A, B and C (Tn vs Cn) were: A (1.56) (95% CI, 1.04-2.34), B (1.43) (95% CI, 0.90-2.25), C (0.38) (95% CI, 0.24-0.6). CONCLUSIONS: Intermediate troponin values are associated with diagnosis of heart disease, especially ACS.

A multicentre analysis of four low-density lipoprotein cholesterol direct assays in samples with extreme high-density lipoprotein cholesterol concentrations.

BACKGROUND: Although LDL-C has been traditionally estimated using the Friedewald formula (FF), several direct homogeneous assays have been developed to overcome the limitations of this formula and the complicated manual procedure required in the reference method. However, several differences have been reported between these assays in certain situations. METHODS: Two groups of 105 samples with extreme low and high HDL-C concentrations were processed, employing four different instruments and with the reagents for total cholesterol, triglycerides, HDL-C and LDL-C provided by the distinct manufacturers. RESULTS: Statistical tests indicated important differences between HDL-C and LDL-C homogeneous methods. Poor correlation, significant bias and high discrepancy in cardiovascular disease risk classification were observed for LDL-C direct assays in the low HDL-C group, whereas better results were obtained when comparing LDL-C levels estimated with the FF. In contrast, three of the four instruments generated LDL-C direct results with a good agreement in the high HDL-C group, even though an appreciable misclassification percentage in risk categories must be taken into account. CONCLUSIONS: Our results indicate that extreme low or high HDL-C levels can represent a non-previously described source of variation between commercially available LDL-C homogeneous assays.

Prevalence and progression of mitochondrial diseases: a study of 50 patients.

We report 50 patients with various clinical phenotypes of mitochondrial disease studied over the past 10 years in a large urban area (Madrid Health Area 5). The clinical phenotypes showed a large variety of abnormalities in molecular biology and biochemistry. The prevalence of mitochondrial diseases was found to be 5.7 per 100,000 in the population over 14 years of age. Clinical and electrophysiological assessment reveal signs of neuropathy in 10 patients. Electromyographic findings consistent with myopathy were obtained in 37 cases. Six patients died of medical complications. Disease phenotype influenced survival to some degree (P < 0.01). Age of onset and gender were not associated with differences in survival. Mitochondrial disease is thus far more common than expected and a common cause of chronic morbidity.