The HLA antigens in 40 patients with subacute thyroiditis were investigated. An association between subacute thyroiditis and HLA-Bw35 antigen as previously reported, was confirmed. Further immunological observations included a decrease in Serum Clq, C4 and C3 activator levels; conversely, there was an increase in serum C3, IgM, alpha1-acid glycoprotein and alpha1-antitrypsin levels. Serum IgA levels were decreased in those patients who were Bw35 negative, but were normal in the patients who were Bw-35 positive, with serum alpha2-macroglobulin levels the opposite was found. These studies support the view that a genetic factor(s), viz., the major histocompatibility system, plays a role in the pathogenesis of subacute thyroiditis. A "nosological clustering" around the Bw35 antigen as a marker for viral susceptibility is suggested.

These results indicate that since serum IMg2+ and % IMg2+, but not TMg, can be altered by dietary intake, previous or future findings which may indicate no change in TMg by diet may not reflect changes in biologically-active Mg.

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Magnesium plasma concentrations were measured in healthy probands before and after administration of trimagnesium dicitrate by the oral and intravenous routes. There was a notable circadian fluctuation of the plasma concentration with a peak in the evening hours. After oral administration of 12 and 24 mmol magnesium, a long-lasting, statistically significant increase in plasma magnesium concentration measured as the increase in area under the curve (AUC) between 0 and 12 h, of 3.1% and 4.6%, respectively, was found. After intravenous administration of 4 and 8 mmol magnesium, AUCs increased by 9.5% and 16.1%, respectively. The decline in the plasma magnesium concentration after i.v. administration was compatible with a three-compartment model with a terminal half-time of about 8 h. Although no absolute value of the oral bioavailability of trimagnesium dicitrate could be determined from the data, our results may be important in helping to elucidate the influence of magnesium preparations on the plasma magnesium concentration. By comparing the effects of different preparations, it should be possible to estimate the relative oral bioavailability and the bioequivalence of these preparations.

No abstract