Associations between serum ferritin and cardiovascular risk factors in healthy young men. A cross sectional study.

OBJECTIVE: This study examines the association between serum ferritin levels and cardiovascular risk factors. DESIGN: The data were obtained from a cross-sectional survey designed to assess the nutrition situation, with special reference to cardiovascular risk factors. SUBJECTS AND SETTING: The study population was 337 healthy men, median age 38 years (range 21-59), working at oil platforms in the North Sea. RESULTS: The associations between serum ferritin, risk factor levels and anthropometric measurements were analysed by age-adjusted partial correlations, step-wise multiple regression, and one-way ANOVA analysis. Body mass index and waist-to-thigh ratio were the strongest predictors for serum ferritin when controlling for age (P < 0.001). In multiple regression analysis, when anthropometric measurements were excluded, fibrinogen, high density lipoprotein (HDL)-cholesterol and diastolic blood pressure were significant predictors for serum ferritin levels when controlling for age (P < 0.001). There was a significant difference in triglyceride concentration between those with low stores of iron and those with high stores (P = 0.006). There were consistently higher levels of total cholesterol, triglycerides, fibrinogen, diastolic and systolic blood pressure, except for HDL where it was reversed, in the highest quartile of serum ferritin levels compared to the lowest. For all the variables the differences between the quartiles of serum ferritin were significant. CONCLUSION: These findings support the hypothesis that the associations between cardiovascular arteriosclerotic disease and serum ferritin are at least partially caused by confounding. SPONSORSHIP: The project was supported by the Norwegian State Oil Company (STATOIL), Amoco Norway Oil Company and Ross Offshore AS.

Impairment of rat polymorphonuclear neutrophilic granulocyte phagocytosis following repeated hypobaric hypoxia.

Exposure of rats to repeated hypobaric hypoxia (17 h at 0.5 atm for 0-7 d) induced significant reduction of the phagocytic capacity of peripheral blood polymorphonuclear neutrophilic granulocytes (PMNL). In addition, the hypoxia induced a significant increase of the hematocrit, hemoglobin, thrombocyte, and total leukocyte concentrations. Differential counting of peripheral blood revealed significant granulocytosis. An increase of the concentration of corticosterone was demonstrated following 2 d of hypobaric hypoxia, whereas 5 d later the corticosterone concentrations were similar to that of the controls. The reduced PMNL phagocytic capacity observed following repeated hypobaric hypoxia may have consequences for host defence in situations of hypoxia exposure.

Reduced systolic blood pressure elevations during maximum exercise at simulated altitudes.

Ten healthy female subjects performed maximum exercise on a bicycle in an altitude chamber during normoxia and hypobaric hypoxia simulating altitudes of 2,450, 3,700 and 4,600 m. The increases in systolic blood pressure responses were reduced with the degree of hypobaric hypoxia, whereas heart rate and diastolic pressure responses were unchanged. The increases in blood levels of aldosterone, plasma renin activity, adrenaline, noradrenaline, neuropeptide-Y and vasoactive intestinal peptide were similar at the different simulated altitudes. Angiotensin-converting enzyme and vasoactive intestinal peptide levels were not affected by hypoxia or maximum exercise. The present results suggest that the decreases in systolic blood pressure responses during hypobaric hypoxia could not be explained by altered responses of the measured vasoactive substances from the renin-angiotensin, gastrointestinal, and autonomic nervous systems.