Studies of thyroid and sympathetic nervous system interrelationships. II. Effects of guanethidine on manifestations of hyperthyroidism

The Pharmacotherapy of Thyroid Storm

A review of thyrotoxic storm is presented. Included are causes, symptomatology, and mortality rates. Special emphasis is placed on the strong correlation between adrenergic blockade and success rates in treating thyrotoxic storm. Pharmacotherapy of the acute storm patient is discussed in detail with respect to agents that (1) decrease production of thyroid hormones; (2) block release of preformed thyroid hormones from the gland; (3) blunt the effects of excess thyroid hormones on the various target organs (e.g., CNS and heart); and (4) serve to decrease the metabolic strain on all organ systems caused by thyrotoxic storm.

Peri-operative management of severe thyrotoxicosis with esmolol

A case of severe thyrotoxicosis with cardiac decompensation is reported. Use of propranolol was followed by cardiovascular collapse. Esmolol, the beta-1 adrenoceptor blocking agent was successfully used to control the thyrotoxic state. A discussion of possible advantages of esmolol is provided.

Plasma concentration of gonadotrophins, oestrogens and progesterone in thyrotoxic women

Plasma levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), oestrogen and progesterone were measured daily in 15 thyrotoxic women in the reproductive age for 28 to 30 consecutive days before commencement of therapy and for a similar period following restoration of the euthyroid state. Five of these patients had secondary amenorrhoea whilst the other 10 had hypomenorrhoea. Twelve healthy volunteer eythyroid women of similar age and parity, with no history of menstrual abnormality, served as controls. The levels of both gonadotrophins (LH and FSH) and oestrogen were found to be significantly raised in all thyrotoxic patients in comparison with levels in the euthyroid female controls (P less than 0.001). "Mid cycle" LH and FSH peaks were present in thyrotoxic patients who were still menstruating whilst they were absent in those who developed amenorrhoea. Plasma oestrogen concentration rose to a peak on the day before the surge of LH (and FSH) in all euthyroid frmale controls as well as in thyrotoxic patients who were still menstruating. In contrast, oestrogen peaks occurred without ensuing LH (and FSH) peaks in thyrotoxic patients who had developed amenorrhoea, suggesting a failure of the positive feed-back mechanism. The levels and patterns of plasma progesterone in thyrotoxic subjects who were still menstruating were similar to those of euthyroid controls. However, no significant circulating plasma progesterone was detected in thyrotoxic subjects who were amenorrhoeic. The levels and patterns of all of these hormones (gonadotrophins, oestrogen and progesterone) became normal after restoration of euthyroid state and normal menstruation.

Atrial fibrillation and hyperthyroidism: a new look at their relationship and therapy with lidoflazine

Various kinds of dysrhythmias are found in association with hyperthyroidism but especially atrial fibrillation. The causal relationship of chronic atrial fibrillation and the endocrine disorder is controversial, as is its therapeutic management. Six patients with this particular combination of disorders were treated with lidoflazine: a new anti-anginal drug with anti-arrhythmic activity. All six patients returned to sinus rhythm on lidoflazine treatment although still hyperthyroid and remained in sinus rhythm during the follow up period ranging from 5 to 14 months. This occurred independently of antithyroid treatment. Some evidence is put forward that dysrhythmias and most commonly chronic atrial fibrillation are triggered off by hyperthyroidism or other disorders but that they are maintained by permanent cardiac damage due to arteriosclerosis, hypertension, coronary heart disease or rheumatic valve disease.

Successful chemical cardioversions and maintenance of sinus rhythm can be obtained independent of the thyroid function. Our results confirm the anti-arrhythmic activity of lidoflazine.

Influence of thyroid hormones on the sensitivity of cardiac and smooth muscle to biogenic amines and other drugs

1. Rats and guinea-pigs were injected with 1-thyroxine or thyroidectomized. Sensitivity of isolated tissues and of the intact cardiovascular system to drugs was investigated.2. Thyroxine increased the sensitivity of the isolated perfused heart to noradrenaline, adrenaline, isoprenaline, acetylcholine and histamine.3. Thyroxine increased the sensitivity of the rat isolated uterus to noradrenaline, adrenaline, isoprenaline, acetylcholine, histamine and 5-hydroxytryptamine.4. In contrast, thyroxine decreased the sensitivity of the isolated ileum to acetylcholine, histamine and 5-hydroxytryptamine, but not to adrenaline.5. Thyroxine also decreased the sensitivity of the isolated aorta to noradrenaline, adrenaline, histamine and 5-hydroxytryptamine.6. In pithed rats, thyroxine potentiated pressor responses to (+)-amphetamine but not to noradrenaline or synephrine.7. In anaesthetized thyroxine-treated rats, blood pressure responses to (+)-amphetamine were potentiated while those to noradrenaline were unaltered. Responses to acetylcholine were increased, and the response to isoprenaline became purely pressor.8. Thyroxine-induced changes in the sensitivity of the isolated uterus and ileum to modification of the concentration of calcium in the physiological salt solution paralleled the changes in drug sensitivity of these tissues.9. In general, thyroidectomy produced the opposite effects to those of thyroxine.10. It is concluded that there is no specific interaction between thyroxine and sympathomimetic amines, the effect of thyroxine on drug sensitivity being non-specific.

Thyroid and adrenal relationships

A brief review of the actions of adrenal medullary and thyroid hormones is presented and the ways in which they interact are examined. It is concluded that thyroid hormone produces the necessary intracellular environment without which the steady state and emergency actions of cathecholamines would be vitiated. In hyperthyroidism the increased concentration of thyroid hormones results in a lowering of the threshold for catecholamine action. For this reason it is possible to alleviate many of the symptoms of thyrotoxicosis by means of drugs which block β-adrenergic receptors.

Attention is also drawn to the simultaneous occurrence of thyroid and adrenal disease, in the hope that this will encourage the search for further links in this field of endocrinology.