Beta-blockade and partial thyroidectomy for thyrotoxicosis

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.

Hyperthyroidism, exophthalmos, and goiter: historical notes on the orbitopathy

BACKGROUND

Exophthalmos associated with goiter and/or symptoms of hyperthyroidism have been known since antiquity. It was not until around 1800 that a number of studies described this disorder in more detail.

SUMMARY

For many years the nature of the disease remained unclear and it was appreciated as either a cardiac or neurological disease. There was no agreement on treatment. Surgery on the thyroid, orbit, autonomous nerve system, and pituitary has been employed. Medical treatment was introduced around World War II. Later, as a consequence of the discovery of long-acting thyroid stimulator, it became apparent that Graves-Basedow's disease was an autoimmune disease and so was the exophthalmos, though many details of the pathophysiology remain in doubt.

CONCLUSIONS

This article presents a brief review of the history of the exophthalmos associated with thyroid disease.

Beta-adrenergic blockade for the treatment of hyperthyroidism

PURPOSE

To review the clinical and biochemical effects of beta-adrenergic blocking drugs on hyperthyroidism.

MATERIALS AND METHODS

Studies published since 1972 were identified through a computerized search of MEDLINE and extensive searching of the bibliographies of the articles identified. Based on an understanding of the differences in beta-blocker metabolism in euthyroid and hyperthyroid patients, we reviewed the differences in pharmacokinetics and metabolic and clinical outcomes during their use in hyperthyroidism, as reported in the articles reviewed.

RESULTS

beta Blockers have been used to modify the severity of the hyperadrenergic symptoms of hyperthyroidism for the past 20 years. The clinical efficacy of these agents is affected by hyperthyroid-induced alterations in their gastrointestinal absorption, hepatic metabolism, and renal excretion. The mechanisms whereby these clinical changes are effected is unknown. The agents differ in their beta 1 cardioselectivity, membrane-stabilizing activity, intrinsic sympathomimetic activity, and lipid solubility. They do not appear to alter synthesis or secretion of thyroid hormone by the thyroid gland. Their effects on thyroxine metabolism are contradictory. Decreased thyroxine to triiodothyronine conversion is caused by some, but not all, beta blockers, and this appears to correlate with membrane-stabilizing activity. There does not appear to be any alteration in catecholamine sensitivity during beta-adrenergic blockade.

CONCLUSIONS

The principal mechanism of action of beta blockers in hyperthyroidism is to antagonize beta-receptor-mediated effects of catecholamines. beta Blockers are effective in treating hypermetabolic symptoms in a variety of hyperthyroid states. Used alone, they offer significant symptomatic relief. They are also useful adjuvants to antithyroid medications, surgery, and radioactive iodide treatment in patients with Graves' disease and toxic nodular goiters.

The selective beta 1-blocking agent metoprolol compared with antithyroid drug and thyroxine as preoperative treatment of patients with hyperthyroidism. Results from a prospective, randomized study

Despite the increasing use of beta-blocking agents alone as preoperative treatment of patients with hyperthyroidism, there are no controlled clinical studies in which this regimen has been compared with a more conventional preoperative treatment. Thirty patients with newly diagnosed and untreated hyperthyroidism were randomized to preoperative treatment with methimazole in combination with thyroxine (Group I) or the beta 1-blocking agent metoprolol (Group II). Metoprolol was used since it has been demonstrated that the beneficial effect of beta-blockade in hyperthyroidism is mainly due to beta 1-blockade. The preoperative, intraoperative, and postoperative courses in the two groups were compared, and patients were followed up for 1 year after thyroidectomy. At the time of diagnosis, serum concentration of triiodothyronine (T3) was 6.1 +/- 0.59 nmol/L in Group I and 5.7 +/- 0.66 nmol/L in Group II (reference interval 1.5-3.0 nmol/L). Clinical improvement during preoperative treatment was similar in the two groups of patients, but serum T3 was normalized only in Group I. The median length of preoperative treatment was 12 weeks in Group I and 5 weeks in Group II (p less than 0.01). There were no serious adverse effects of the drugs during preoperative preparation in either treatment group. Operating time, consistency and vascularity of the thyroid gland, and intraoperative blood loss were similar in the two groups. No anesthesiologic or cardiovascular complications occurred during operation in either group. One patient in Group I (7%) and three patients in Group II (20%) had clinical signs of hyperthyroid function during the first postoperative day. These symptoms were abolished by the administration of small doses of metoprolol, and no case of thyroid storm occurred. Postoperative hypocalcemia or recurrent laryngeal nerve paralysis did not occur in either group. During the first postoperative year, hypothyroidism developed in two patients in Group I (13%) and in six patients in Group II (40%). No patient had recurrent hyperthyroidism. The results suggest that metoprolol can be used as sole preoperative treatment of patients with hyperthyroidism without serious intra- or postoperative complications. Although the data indicate that the risk of postoperative hypothyroidism is higher after preoperative treatment with metoprolol than with an antithyroid drug, a longer follow-up period than 1 year is needed to draw conclusions regarding late results.

Lugol's iodine: its effect on thyroid blood flow in patients with thyrotoxicosis

It has been established practice for 60 years to prepare thyrotoxic patients undergoing thyroidectomy with Lugol's iodine. However, evidence in support of its claimed benefits, namely a reduction in the vascularity and friability of the toxic thyroid gland, is scanty. We have therefore determined the effect of Lugol's iodine on thyroid blood flow, as measured by thyroid uptake of thallium-201, in nine patients with Graves' disease and one euthyroid patient. Thallium-201 uptake, as well as serum thyroxine and triiodothyronine, fell significantly after treatment with iodine. Although not correlated with thyroid function tests, thallium-201 uptake was significantly correlated with thyroid weight. These results support the contention that thyroid blood flow is reduced in thyrotoxic patients treated with Lugol's iodine.

Effect of propranolol treatment on bone mass, bone mineral content, bone remodelling, parathyroid function and vitamin D metabolism in hyperthyroidism

The effect of propranolol 160-640 mg/day for 3 months on the accelerated loss of bone matrix and mineral in hyperthyroidism was studied in seventeen patients. A rise in serum thyroxine (P less than 0.01) during the first 3 weeks was followed by a fall (P less than 0.02). Serum triiodothyronine declined during the study (P less than 0.02). The enhanced bone mineral mobilization and collagen turnover continued during treatment and the bone mineral content decreased 3.2% (P less than 0.01). The secondary adaptive changes in serum parathyroid hormone and vitamin-D metabolites and in renal phosphate handling stayed unchanged. Iliac crest bone biopsies after tetracycline double-labelling showed initially a high bone turnover (P less than 0.01) with a reduced amount of cortical and trabecular bone (P less than 0.05). Following treatment bone formation rate decreased at both cellular and tissue level (P less than 0.01). No significant changes were observed in the amount of cortical and trabecular bone. The investigation shows that propranolol, in contrast to antithyroid medication, lacks any curative effect on the accelerated bone loss in hyperthyroidism.

Beta-adrenoceptor blockade and anaesthesia for thyroidectomy

The administration of beta-adrenoceptor blocking drugs in the pre-operative preparation and operative management of thyrotoxic patients undergoing subtotal thyroidectomy is reviewed. Particular reference is made to some of the recent advances and it is emphasised that there has been a considerable reduction in the incidence of problems following judicious use of these drugs. The choice of anaesthetic technique employed for thyroidectomy is less important than the degree of control of thyrotoxicosis by the beta-adrenoceptor blocking drug. Propranolol has proved safe and effective for the majority of patients. The longer acting agent nadolol is easier to administer, particularly in the peri-operative period. Patients are rendered less thyrotoxic and safety thereby enhanced by adding potassium iodide for 10 days preoperatively. The combination of nadolol and potassium iodide offers real advantages in the preparation of the thyrotoxic patient for surgery.

A beta-blocker as anxiolytic and haemostatic in tonsillectomy

Administration of a beta-blocker, pindolol, was utilized in the premedication of patients selected for tonsillectomies (dissection), to study anxiolytic effects. A curious result observed was that bleeding during and after operation in patients on pindolol was remarkably reduced compared to those not on beta-blocker treatment. This effect was further explored in a small controlled study. Nineteen patients were given pindolol, 5 mg the evening before and on the morning, an hour prior to surgery. Seventeen controls were on placebos. The amount of bleeding was measured in both groups. Patients on pindolol show significantly reduced bleeding when compared to controls (1.77 +/- 1.15 ml versus 7.30 +/- 6.05 ml; p less than 0.005). Coagulation and fibrinolytic profiles were studied in a number of patients in both groups attempting to clarify the cause of the reduced bleeding. The results will be reported. This preliminary study shows that pindolol is a useful drug for controlling bleeding in tonsillectomies. To our knowledge the haemostatic properties of pindolol have been reported before.

Nadolol and potassium iodide in combination in the surgical treatment of thyrotoxicosis

With the two aims of rapidly reducing circulating thyroid hormone levels and controlling the symptoms of thyrotoxicosis, we have prepared 17 thyrotoxic patients for subtotal thyroidectomy, using a combination of potassium iodide administered for 10 days and the long acting beta-adrenoceptor antagonist nadolol. All 17 patients had normal serum thyroxine levels after 10 days of such treatment although 10 still showed elevation of serum tri-iodothyronine and considerable elevation in the most severely toxic patient. All patients were, however, clinically euthyroid preoperatively. Nadolol was administered once daily, hence avoiding the problems of drug administration in the immediate postoperative period, and plasma nadolol concentrations were high throughout the perioperative period. Serum thyroxine and tri-iodothyronine levels were significantly lower and reverse tri-iodothyronine levels higher 24 h postoperatively than before operation. All patients remained stable throughout the perioperative period. We conclude that this regimen has a number of advantages in the preparation of patients for thyroidectomy, in reducing the degree of thyrotoxicosis, in convenience of drug administration and in ensuring adequate circulating concentrations of beta-adrenoceptor antagonist whilst still retaining a relatively short preoperative phase of drug treatment.

Sotalol in hyperthyroidism

Ten hyperthyroid patients were studied before and after 2 weeks' beta-adrenoceptor blockade with sotalol. The following variables were measured: resting pulse rate, blood pressure, weight, thyroid hormone levels, plasma lipids, alkaline phosphatase, plasma glucose and insulin responses to oral glucose, bromsulphthalein retention and the 24-h urinary excretion of calcium, hydroxyproline, creatine and creatinine. Sotalol produced a significant fall in pulse and blood pressure. Weight loss continued during treatment. No metabolic changes of any consequence were found. It is concluded that sotalol should not be used as the sole treatment of a patient with hyperthyroidism.

Propranolol in the surgical treatment of hyperthyroidism, including severely thyrotoxic patients

The perioperative course of 44 hyperthyroid patients prepared for surgery with propranolol alone, including 11 with severe thyrotoxicosis was compared to that of 20 euthyroid patients prepared for surgery with carbimazole. Conventional propranolol at a dosage of 160 mg/day was frequently insufficient to produce a high degree of beta-adrenergic blockade, particularly in severely thyrotoxic patients. A greater than 25 per cent reduction in sitting pulse rate was associated with a high degree of beta-blockade. The clinical course of patients with mild or moderate thyrotoxicosis was similar to that of the patients prepared with carbimazole. In contrast, the course of severely thyrotoxic patients was complicated and, in addition to a higher preoperative propranolol dosage, these patients commonly required supplemental propranolol after operation. Although thyroid crisis did not occur in any patient, we cannot recommend the use of propranolol alone for the severely thyrotoxic patient.

Altered endocrine response to partial thyroidectomy in propranolol-prepared hyperthyroid patients

The endocrine response to partial thyroidectomy in a group of twenty hyperthyroid patients prepared with propranolol alone was compared to that of a matched control group of ten euthyroid patients. In propranolol-prepared patients the glucose response to surgery was reduced (P less than 0.05) for up to 4 h post-operatively and biochemical hypoglycaemia was noted in one patient. Both thyroxine and triiodothyronine (T3) fell significantly, associated with a marked rise in reverse T3. Growth hormone levels were higher (P less than 0.05) both pre- and post-operatively in propranolol-prepared patients, whereas prolactin levels, although similar pre-operatively, were lower (P less than 0.05) in these patients post-operatively. Cortisol and ACTH levels were lower (P less than 0.05) both before and following thyroidectomy in propranolol-prepared patients. These results suggest that the endocrine response to surgical stress is markedly altered in propranolol-prepared hyperthyroid patients.

Metabolic response to subtotal thyroidectomy in propranolol-treated thyrotoxic patients

Changes in plasma cortisol, glucose, cyclic AMP, blood leucocytes, pulse rate and body temperature were measured during and for 24 h after subtotal thyroidectomy in eight propranolol-treated (120-160 mg per day) mild to moderate thyrotoxic patients and eight patients with a non-toxic goitre. The results showed a similar metabolic response to surgery in the two groups without any trends towards a hypermetabolic response in the toxic group. The accumulating evidence of the safety of preoperative preparation with propranolol in patients with mild to moderate thyrotoxicosis is thus supported by our results.

Prolonged effect of nadolol on heart rate in hyperthyroidism

There is extensive experience in the treatment of hyperthyroidism with beta-blockade. Because of the short half-life of propranolol the drug must be taken in divided doses. The effect of a single daily dose of a long-acting beta-blocking drug, nadolol, was investigated in 7 hyperthyroid patients. A satisfactory and prolonged reduction in heart rate was observed during continuous monitoring over a 24-hour period. Nadolol, therefore, is a possible alternative to propranolol in the treatment of hyperthyroidism with an advantage in the poorly-compliant patient.

Cortisol, growth hormone and prolactin responses to insulin-induced hypoglycaemia in hyperthyroid patients before and during beta-adrenoceptor blockade

Two beta-adrenoceptor blocking agents, metoprolol (beta-1-selective) and propranolol (non-selective), were used in the treatment of hyperthyroid patients. The response of pituitary stress hormones to insulin-induced hypoglycaemia was investigated before and during beta-adrenoceptor blockage. Treatment with metoprolol (n=10) or propranolol (n=10) produced no changes in the cortisol or prolactin responses to hypoglycaemia. Moreover the growth hormone response remained unaltered during treatment with metoprolol. A small, but statistically significant, augmentation of growth hormone response was obtained during treatment with propranolol. When twelve subjects, euthyroid after final conventional treatment (surger), radioiodine or thyrostatic drugs), were re-examined, the cortisol and prolactin responses were unchanged, although growth hormone concentrations reached a slightly higher maximum value (P less than 0.01). It was concluded that treatment with beta-blocking agents in hyperthyroid subjects has no clinically important influence on the release of pituitary stress hormones during hypoglycaemia.

Combination of potassium iodide and propranolol in preparation of patients with Graves' disease for thyroid surgery

We assessed the efficacy of the combination of propranolol and potassium iodide in the preparation of patients with Graves' disease for thyroid surgery. Potassium iodide was given orally in a dose of 60 mg three times a day for 10 days before operation in 10 patients who were already receiving propranolol. In contrast to previous experience with either drug used singly, the combined regimen caused a significant fall in mean serum total thyroxine and triiodothyronine to levels in the euthyroid range before operation (P less than 0.001). There was also a significant fall (P less than 0.05) before operation and transient rise after operation in serum reverse triiodothyronine. These preliminary results suggest that the combination of potassium iodide and propranolol may prove to be the optimum preoperative preparation for patients with Graves' disease.

Propranolol therapy in thyrotoxicosis. A review of 84 patients undergoing surgery

The effect of propranolol on the surgical course of 84 thyrotoxic patients undergoing partial thyroidectomy or extrathyroidal surgery was evaluated. Seventy-two patients (group 1) underwent surgery with propranolol as their sole preparatory medication, whereas in 12 (group 2) surgery was carried out after a rather prolonged period of thionamide preparation with the addition of propranolol preoperatively as an adjunctive therapeutic agent. Preoperative pulse rate and systolic blood pressure levels fell in both groups, and the clinical features of thyrotoxicosis were rapidly ameliorated with an average dose of propranolol of 330 mg (range 40 to 1,280 mg) daily. Maximal clinical response occurred within 48 to 72 hours of starting propranolol therapy. In 14 patients in group 1, paired serum calcium levels were reduced by the administration of propranolol preoperatively; serum thyroxine levels were unchanged. Serum thyroxine decay, evaluated postoperatively in the patients in group 1, was decreased. The half life of thyroxine was inversely related to the initial thyroxine levels. Analysis of these data indicates that the administration of propranolol alone provides rapid, safe and effective preparation of thyrotoxic patients for emergency or for elective thyroidal or extrathyroidal surgical procedures.

Reemergence of thyroidectomy as treatment for Graves' disease

Hyperthyroidism of Graves' disease may be treated very effectively by antithyroid pills, such as PTU and Tapazole, by radioactive iodine therapy, and by subtotal thyroidectomy. Each form of therapy has advantages and disadvantages, and thus treatment should be individualized. While therapy with radioactive iodine would appear to be ideal since it does not require an operation and is less expensive than surgical management, it suffers from a high rate of progressive hypothyroidism and from the fact that the time until a euthyroid state is obtained is often prolonged. In addition, the long-term carcinogenic risk of the therapy for thyroid neoplasia has never been completely defined since the data most often quoted have a mean follow-up time of only eight years. Furthermore, new "low-dose" radioiodine regimens may be more dangerous in this regard. Subtotal thyroidectomy, while not totally without complications, remains a rapid, safe, and effective treatment for Graves' disease. The careful use of propranolol has facilitated the preparation of some patients and has lessened the risk of operation. Thyroidectomy should remain the treatment of choice for young adults with this disease.

Propranolol in thyrotoxicosis. Cardiovascular changes during thyroidectomy in patients pre-treated with propranolol

The cardiovascular changes during anaesthesia and thyroidectomy have been studied in seven thyrotoxic patients prepared with propranolol. The heart rate and cardiac rhythm remained very stable throughout surgery. A 20% increase in mean arterial pressure occurred during surgical stimulation. A decrease in cardiac output, due to decreased stroke volume, occurred during surgical stimulation. A decrease in cardiac output, due to decreased stroke volume, occurred during surgery, reaching a maximum of 21% during ligation of the thyroid vessels and returning to pre-operative values by the end of surgery. The fall in cardiac output was accompanied by raised central venous pressure and raised total peripheral resistance.

Thyroid function after surgical treatment of thyrotoxicosis. A report of 100 cases treated with propranolol before operation

We assessed thyroid function for 12 months after subtotal thyroidectomy in 100 tyrotoxic patients treated with propranolol alone before and immediately after operation. The operation proved safe, with low morbidity. Suppression of the hypothalamic-pituitary-thyroid axis, present in the majority one month after operation, was evidenced by normal or low levels of serum total tri-iodothyronine and thyroxine, but absent or subnormal serum thyrotropin response to thyrotropin-releasing hormone. Eighty patients were euthyroid at 12 months. Three patterns of thyroid function were observed in this group between the first and 12th months: normal serum total tri-iodothyronine, thyroxine and thyrotropin levels at all stages (20 patients); normal serum total tri-iodothyronine and thyroxine, but raised thyrotropin levels on one or more occasions (40 patients); and temporary hypothyroidism (20 patients). Of the remaining 20 patients, permanent hypothyroidism developed in 14, and six relapsed. Postoperative thyroid function was related to the estimated weight of the thyroid remnant.

Effect of propranolol on glucose tolerance in hyperthyroidism

Glucose tolerance tests were performed on six hyperthyroid patients in the morning and afternoon before, and at the end of treatment with propranolol for 2 weeks. All six subjects showed normal glucose tolerance with a normal diurnal rhythm before treatment and this remained normal in five during treatment with propranolol, while one patient developed abnormal glucose tolerance and the diurnal variation was abolished. No change in insulin levels was noted in any of the patients either before or during treatment. Propranolol may cause deterioration in glucose tolerance in some subjects with hyperthyroidism and this possibility should not be overlooked.

Thyroxine and triiodothyronine levels in hyperthyroid patients during treatment with propranolol

Serum triiodothyronine (T3) and thyroxine (T4) levels were measured in twelve hyperthyroid patients before and after treatment with propranolol, 40 mg four times daily, for 2 weeks. There was a significant fall in serum T3 and a significant rise in serum T4 concentrations in the group as a whole and it was concluded that the clinical effectiveness of propranolol in hyperthyroidism may be mediated in part by its action on the peripheral metabolism of thyroid hormones. Propranolol treatment should be withdrawn gradually as removal of the suppressive action of the drug on thyroid hormone metabolism is potentially hazardous, particularly in patients with ischaemic heart disease.

Radical mastectomy in a patient with coexistent Graves' disease

A patient with the coincidental occurrence of thyrotoxicosis and medullary carcinoma of the breast is reported. Survivorship was considered optimal by performance of a mastectomy without the six to eight weeks' delay required to achieve euthyroidism by antithyroid drugs or radioiodine. The hyperthyroidism was controlled with propranolol, permitting an uneventful radical mastectomy.

Assessment by continuous cardiac monitoring of minimum duration of preoperative propranolol treatment in thyrotoxic patients

The effect of the beta-blocker, propranolol (40 mg 6-hourly orally) has been studied on the tachycardia of six patients with untreated thyrotoxicosis. Heart rate was monitored continuously using a light portable ECG recorder which allowed the patients to undertake normal activities during the recording periods. The most marked reduction in heart rate was evident at 24 h after starting propranolol treatment. In three of the patients there was only a minor further fall in heart rate despite continued propranolol administration, but in the remaining patients the reduction in heart rate with each successive day of treatment was more marked. These results suggest that if propranolol were to be used alone in the preparation of patients before partial thyroidectomy for thyrotoxicosis, a dose of 40 mg 6-hourly for 3-4 days might be sufficient.

Rational therapy for thyroid storm

An approach to the management of patients with thyroid storm is described. The treatment regimen, which is directed against the abnormalities as they are presently understood, incorporates: (a) Propranolol to inhibit the catecholamine-mediated peripheral effects of the circulating thyronines; (b) Propylthiouracil to inhibit thyroid hormone synthesis and to inhibit peripheral conversion of thyroxine to triiodothyronine (T3), the predominant source of T3 production; (c) Iodine to block the glandular release of thyroid hormones; (d) Dexamethasone along with general supportive therapy. The regimen has been used for a 13 year old schoolgirl with thyroid storm, and the induced rapid fall in serum T3 levels is illustrated. It has also been used in patients with florid thyrotoxicosis undergoing emergency surgery and has resulted in marked clinical improvement associated with rapid decreases in serum T3 levels. It is a simple and efficient regimen, rendering cumbersome forms of therapy such as plasmapheresis and peritoneal dialysis unnecessary.

Whither thyrotoxicosis?

For 30 years the thyrotoxic patient has been subjected to a plurality of treatments by surgery, radio-iodine and long term anti-thyroid drugs. These therapies have been accepted as complementary to the needs of the individual patient, without regard for long term results or the economic situation as it affects both patient and hospital services. In the context of surgical treatment which is now available, it is suggested that the advantages of operation over other therapies presage a reversion to surgery as the treatment of choice.