Thyroid function has been investigated in 24 young military cadets participating in a 5 d ranger training course with heavy physical exercise, calorie deficiency and deprivation of sleep. The cadets were divided into three groups, each differing in the amount of sleep and food consumption. The serum levels of thyroid hormones (T4, FT4, T3, rT3) and TBG showed a biphasic pattern during the course. Initially there was an increased secretion concomitant with an increased deiodination of T4 to T3 and rT3 mainly due to physical exercise. When the activities lasted for several days without sufficient food supply the thyroid secretion decreased simultaneously with an alteration of the peripheral conversion of T4 to rT3 instead of T3. A significant correlation was found between the changes in total and free thyroxine (r = 0.9) and between the increase in rT3 and decrease in T3 (r = 0.6). TSH decreased during the first day of activities and remained low throughout the course. The TSH response to TRH stimulation was greatly reduced during the course due to physical exercise and calorie deficiency. The present investigation demonstrates that the thyroid function is strongly affected by prolonged physical exercise and a negative energy balance, whereas sleep deprivation does not have any significant influence. The results indicate that the alteration observed is not regulated just by the hypothalamo-pituitary-thyroid-axis alone.
This study suggests that a significant subclinical Mg deficit, not detected by serum Mg, was present in many of these healthy elderly subjects. Mg supplementation improved Mg status and renal function.
Magnesium deficiency is common but difficult to diagnose and to assess in clinical practice. The use of a magnesium loading test was therefore evaluated to diagnose magnesium deficiency in 661 hospitalized patients with medical conditions assumed to interfere with magnesium uptake and excretion. Thirty millimoles of magnesium sulphate were administered intravenously during 8 h as a loading test and related to the urinary excretion in the following 24 h. A group of 30 patients without any known predisposition for magnesium deficiency and a group of 27 healthy volunteers served as controls. The mean (with 95% confidence interval) magnesium retention was 4 (-2-10)% in the control group of patients and 3 (-2-8)% in healthy subjects. A significantly higher retention was observed in all the groups of the patients: atrial fibrillation 18 (11-25)%, other arrhythmias 18 (11-24)%, hypertension 27 (20-33)%, coronary artery disease 25 (20-30)%, congestive heart failure 31 (26-37)%, cerebrovascular events 38 (24-51)%, gastrointestinal disorders 22 (14-29)%, diabetes mellitus 16 (9-22)%, and alcoholics 33 (29-36)%. The percentage of patients with a retention greater than mean + 2 SD of the two control groups varied between 22% and 54% among the different patient groups. The mean serum magnesium among the patient groups was similar to the control group of patients, except for the alcoholics, hypertensives and young healthy controls, who had significantly reduced levels. Magnesium retention was significantly correlated to age and renal function, and among the alcoholics negatively correlated to serum magnesium.(ABSTRACT TRUNCATED AT 250 WORDS)
Magnesium deficiency is common among chronic alcoholics, but the knowledge of oral magnesium supplementation to this group is limited. We, therefore, randomized 49 chronic alcoholics, moderate to heavy drinkers for at least 10 years to receive oral magnesium or placebo treatment for 6 weeks according to a double-blind protocol. Effects on metabolic variables and muscle strength were analyzed. Significant reduction of aspartate-aminotransferase (ASAT), alanine-aminotransferase (ALAT) and gamma-glutamyl-transpeptidase (GGT) were seen after magnesium, whereas no change was observed with placebo. Bilirubin decreased in both groups. Serum Na, Ca, and P increased significantly during magnesium therapy compared with no statistically significant change in the placebo group. Serum K and Mg increased slightly after magnesium supplementation and decreased in the placebo group, resulting in a significant difference between the two groups at the end of the study. Muscle strength increased significantly during magnesium treatment, contrasting to no change with placebo. Blood pressure, heart rate, hematological variables, serum lipids (cholesterol, HDL, TG), glucose tolerance, and creatinine were unchanged in the two groups after treatment. Alcohol consumption was similar before and during the trial and does not explain the differences between the two groups The results shows that short-term oral magnesium therapy may improve liver cell function, electrolyte status, and muscle strength in chronic alcoholics.
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