[Disturbance of synthesis of cholesterol and its precursors in clinically serious conditions]. / Porucha syntézy cholesterolu a jeho prekurzoru u klinicky závazných stavu.

OBJECTIVE: The aim of the study was to elucidate the role and importance of hypocholesterolemia in clinically serious conditions. It was a monocentric, prospective clinical study. MATERIAL AND METHODS: Two groups of patients were recruited to the study--one group were patients with coronary heart disease (CHD), who underwent miniinvasive cardiosurgical operation without extracorporeal circulatio (n = 17) and one group of patients, who sustain polytrauma (n = 19). Thirty six patients were recruited into the study. We performed the determination of sterols (total cholesterol, HDL-cholesterol, LDL-cholesterol, triacylglycerols), and their precursors (beta-sitosterol, campesterol, lathosterol, skvalen), interleukin IL-6 and cortisol in the blood serum. The short version of ACTH stimulation test was performed. The oxidative burst of granulocytes was evaluated. The blood samples were taken on the day of admission, the first, the fourth and the eighth post-operative and post-traumatic day. RESULTS: There was a significant decline of total cholesterol (TC) and LDL-cholesterol level with full recovery during observed period. There was a decline of cholesterol synthesis (lathosterol and lathosterol/cholesterol ratio) together with a decline of total cholesterol. There was a significantly negative correlation between IL-6 level and total cholesterol. Despite no confirmation of disturbance of adrenal function, there was a significantly positive correlation between lathosterol/cholesterol ratio (a de novo cholesterol synthesis marker) and cortisol level after the ACTH stimulation test. There was a significant breakdown of bactericidal function of granulocytes along with a decline of cholesterol level. CONCLUSION: There was decline of endogenous cholesterol synthesis in clinically serious conditions. The cholesterol synthesis rate is negatively influenced by IL-6 level. The rate of endogenous cholesterol synthesis positively correlated with cortisol production by the adrenals and with bactericidal function of granulocytes.

The diagnostic efficacy of urinary fractionated metanephrines measured by tandem mass spectrometry in detection of pheochromocytoma.

BACKGROUND: There are limitations to currently available biochemical tests for pheochromocytoma. Our objective was to evaluate the diagnostic efficacy of a novel tandem mass spectrometry assay for the measurement of fractionated urinary metanephrines in patients suspected to have a pheochromocytoma. We also developed clinically based cut-offs for positivity of this measurement. METHODS: We examined the medical records of 506 patients (including 102 patients with a catecholamine-producing tumour) who underwent measurement of 24-h urinary fractionated metanephrines using tandem mass spectrometry as well as adrenal imaging at Mayo Clinic, Rochester. The cut-offs for positivity were defined as follows: total metanephrines (sum of the metanephrine fractions) 5163 nmol/day, normetanephrine fraction 4001 nmol/day, metanephrine fraction 1531 nmol/day. Receiver operating characteristic (ROC) curves were constructed. RESULTS: The diagnostic efficacy was as follows: normetanephrine fraction sensitivity 87.3% [(95% confidence interval (CI) 79.4-92.4%], specificity 95.0% (92.5-96.8); metanephrine fraction sensitivity 56.9% (47.2-66.1), specificity 95.0% (92.5-96.8); elevation of either normetanephrine or metanephrine fraction sensitivity 97.1% (91.7-99.0) and specificity 91.1% (87.9-93.5). Areas under the ROC curves (AUCs) were 0.972 (95% CI 0.955-0.990) for the normetanephrine fraction, 0.800 (0.741-0.858) for the metanephrine fraction, 0.991 (0.985-0.996) for total metanephrines, and 0.991 (0.985-0.996) for a regression-derived ROC curve incorporating both the metanephrine and normetanephrine fractions. CONCLUSION: Measurement of 24-h urinary fractionated metanephrines by a tandem mass spectrometry assay appears to be an effective biochemical technique in the investigation of pheochromocytoma.