The management of severe hyperthyroidism

Severe hyperthyroidism: aetiology, clinical features and treatment outcome

BACKGROUND

Severe hyperthyroidism (SH) is a serious medical disorder that can compromise life. There have not been systematic studies in which SH has been evaluated in detail. Here, our aims were: (1) to analyse both clinical and analytical features and outcome in patients with SH and (2) to compare these data with those found in more usual forms of hyperthyroidism. Patients and methods All patients diagnosed of SH (free thyroxine, FT4 > 100 pmol/l, NR: 11-23) seen in our endocrinology clinic in the last 15 years were studied and compared with a sample of patients with mild (mH; FT4, 23-50 pmol/l) and moderate (MH; FT4, 51-100 pmol/l) hyperthyroidism. Aetiology, clinical analytical and imaging data at diagnosis, therapeutic response and outcome were registered. Results A total of 107 patients with overt hyperthyroidism (81 females, mean age +/- SD 46.9 +/- 16.1 years) were evaluated. We studied a historic group with SH (n = 21; 14 females, 40.9 +/- 17.2 years) and, as a comparator group, we analyszed the data of 86 hyperthyroid patients (67 females, 48.4 +/- 15.5.6 years, NS) comparable in age and gender. The comparator group was classified in MH (n = 37, 26 females, 47.2 +/- 16.6 years) and mH (n = 49, 41 females, 49.4 +/- 14.8 years). In comparison with mH group, SH patients were significantly (P < 0.05) younger and showed a greater proportion of first episode of thyroid hyperfunction (P < 0.05). Graves' disease was the main aetiology in the three groups, but patients with SH showed the highest titre of TSH-receptor antibodies (TRAb) (P < 0.001). Heart rate and size of goitre were higher in SH group than in mH and MH groups (P < 0.01). Atrial fibrillation was more frequently reported in SH group than in MH and mH groups (15.8%vs. 5.4% and 0%, respectively, P < 0.05).

RESULTS

from logistic regression analysis showed that younger age [OR 0.958 (95% CI, 0.923-0.995), P = 0.026], presence of asthenia [OR 4.35 (1.48-12.78), P = 0.008] and higher heart rate [OR 1.03 (1.01-1.06), P = 0.013] were independent clinical variables associated to SH. SH patients showed similar biochemical parameters in comparison with mH group, except for increased serum aspartate aminotransferase (AST) (P < 0.01) and calcium (P < 0.05) levels, and decreased serum cholesterol (P < 0.05) and albumin (P < 0.05) concentrations. Logistic regression analysis showed that only AST [OR 1.07 (1.02-1.11), P = 0.005] was an independent biochemical variable associated to SH. No differences in the type of therapy, cure rate and time in achieving cure were found in SH subjects in relation to patients with milder forms of hyperthyroidism. FT4 was the only independent predictor of cure [OR 0.98 (CI 95%, 0.97-0.99), P < 0.05].

CONCLUSIONS

Graves' disease is the most common aetiology in patients with SH. This type of hyperthyroidism is usually de novo and is accompanied by more clinical signs, symptoms, and analytical derangements, as well as higher titres of TRAb at diagnosis than milder forms of hyperthyroidism. The present data are not able to show differences in treatment modality, time to achieve cure, and remission rate among patients with mild, moderate and severe hyperthyroidism.

[Surgical therapeutic concept of immune thyropathy]

73 patients with Graves' disease, surgically treated from 1975-1986, were investigated retrospectively. 43 patients, treated by subtotal thyroidectomy (Enderlen-Hotz) and a bilateral thyroid remnant of a total of about 8-12 g, were compared with 30 patients, treated by a modified subtotal thyroidectomy leaving a unilateral thyroid remnant of about 4-8 g, with respect to preoperative duration of disease, indications for surgical treatment, weight of resected specimens, operative complications and postoperative thyroid function. Surgical complications were similar in both groups. After subtotal thyroidectomy 14/43 patients (33%) displayed either recurrent hyperthyroidism (9/43, 21%) or local recurrence of Graves' goiter (3/43, 7%) or both (2/43, 5%). The modified subtotal resected group showed no recurrences of the disease. After subtotal thyroidectomy 11 patients were euthyroid without thyroid medication (26%) compared to only two patients (7%) after the modified procedure of subtotal thyroid resection. To prevent recurrences of goiter as well as hyperthyroidism and, on the other hand, to achieve euthyroid function postoperatively without need for thyroid replacement therapy, subtotal thyroidectomy with a small thyroid remnant of about 4-8 g is recommended for all patients with large goiter and a chronic recurrent course of the disease or with iodine induced thyrotoxicosis. Patients with non-recurrent Graves' disease but large goiter probably benefit from subtotal thyroidectomy with a larger thyroid remnant of about 8-12 g.

Hyperthyroid heart disease

The importance of cardiovascular system involvement in hyperthyroidism has been recognized for many years. In the middle-aged and elderly patient, often with mild but prolonged elevation of plasma thyroid hormones, symptoms and signs of heart failure and complicating atrial fibrillation may dominate the clinical picture and mask the more classical endocrine manifestations of the disease. Pitfalls in diagnosis and the importance of early recognition and treatment are discussed. Despite experimental evidence for a short-term inotropic action of thyroid hormone excess, clinical data support the existence of a reversible cardiomyopathy in hyperthyroidism with impaired contractile reserve. Enhanced myocardial performance at rest primarily reflects the peripheral actions of thyroid hormone excess. Most, if not all, of the cardiac abnormalities return to normal once a euthyroid state has been achieved, although atrial fibrillation may persist in a minority. Optimum treatment requires rapid and definitive antithyroid therapy, usually using a large dose of radio-iodine, and rapid control of heart failure. Systemic anticoagulation is indicated in the presence of atrial fibrillation and should be continued until sinus rhythm has been present for at least three months, either spontaneously or after cardioversion.