Magnesium metabolism in hyperthyroidism and hypothyroidism.

Abstract

In 1939, Hueber (1) reported clinical improvement in patients with thyrotoxicosis after parenteral administration of magnesium. Wiswell (2) subsequently was unable to demonstrate any change in the peripheral metabolism of thyroid hormone in hyperthyroid patients given magnesium sulfate injections, whereas Neguib (3) reported a decrease in size of both toxic and nontoxic goiters and clinical improvement in three thyrotoxic patients given daily injections of magnesium chloride. Tapley (4) demonstrated that the administration of L-triiodothyronine promptly produced negative magnesium balance in two myxedematous patients and called attention to the similarity between the symptoms of thyrotoxicosis and magnesium deficiency, as well as between myxedema and magnesium excess. That the serum magnesium is elevated in hypothyroidism and decreased in hyperthyroidism has long been known (5-7) but has recently been re-emphasized and associated erythrocyte magnesium alterations reported (8).Dempsey and Astwood (9) demonstrated increased production of thyroid hormone in animals maintained in the cold. Hegsted, Vitale, and McGrath (10) reported that the magnesium requirement to maintain maximal growth rates in animals kept at cold temperatures were four times * Submitted for publication December 6, 1965; accepted February 24, 1966. These studies were carried out in our Clinical Center for Metabolic Studies (U. S. Public Health Service grant AM05578-AMP) and were supported in part by U. S.Public Health Service grant NB 03152.A preliminary report has appeared (Proceedings of the Central Society for Clinical Research 1965, 38, 39 those of animals kept at normal temperatures. Vitale, Hegsted, Nakamura, and Connors (5) later reported that the growth inhibition caused by the addition of thyroxin to the diet of young rats could be partially overcome by extra supplements of magnesium. Magnesium inhibits the action of thyroxin on uncoupling of oxidative phosphorylation in vitro. Conflicting reports exist as to the influence of magnesium deficiency on oxidative phosphorylation (11,12).The present investigation was carried out to assess further the relationship between the functional status of the thyroid gland and magnesium metabolism. Hyperthyroid and hypothyroid patients were studied by determinations of serum and erythrocyte magnesiums, exchangeable magnesiums, and by complete balance studies during therapy with propylthiouracil and triiodothyronine, respectively. MethodsClinical materials. Eight hyperthyroid and eight hypothyroid patients were studied in our clinical center for metabolic studies. Clinical findings were classical, and the diagnoses were confirmed by determinations of protein-bound iodines, 24-hour 'I uptakes, basal metabolic rates, and, in selected hypothyroid patients, repeat 'I uptakes after the intramuscular administration of thyroidstimulating hormone. None of the patients had congestive heart failure or were receiving diuretic agents. Two hyperthyroid patients were taking digitalis for control of arrhythmias...

Magnesium Metabolism in Hyperthyroidism.

“…This is contrary to the findings of Jones et al [7] who got rather lower erythrocyte magnesium after treatment with propylthiouracil.…”

“…Serum magnesium decreased in hyperthyroidism, as previously found by others [7,[12][13][14]. To determine the magnesium level, serum rather than plasma was used to avoid both magnesium contaminated anticoagulants and calcium chelating anticoagulants which also bind magnesium [15].…”

“…Lower levels may occur in severe illness or poor dietary intake. On a controlled diet, Jones et al [7] demonstrated a negative balance for sodium and magnesium in hyperthyroid patients. The amount of sodium and magnesium excreted in urine exceeds the amount reabsorbed.…”

“…Most of the studies of magnesium metabolism in hyperthyroidism did not concomitantly investigate cellular, plasma and urinary magnesium [7,8] The diagnosis was based on typical clinical findings, levels of serum thyroid hormones and TSH [9], and the presence of anti TSH-receptor antibodies.…”

Magnesium Metabolism: A Review

“…In contrast to rats, low serum levels and increased renal losses of magnesium have been found in hyperthyroid patients, while in hyppthyroidism, serum magnesium was increased and urinary magnesium excretion was reduced (156,157). It cannot be said whether the differences in the results obtained in rats and in humans are solely due to species differences, or caused by the difference in pathögenesis of human and experimentally induced disease.…”