The different types of hyperthyroidism in Europe. Results of a prospective survey of 924 patients

Abstract

In a prospective multicentric study, 924 untreated hyperthyroid patients were investigated, coming consecutively within one year into 17 thyroid centers of 6 European countries. With the aid of clinical information, evaluation of thyroid scan and centrally assayed thyroid hormones, thyroid antibodies, TSH-binding inhibiting immunoglobulins (TBII), and urinary iodine, different types of hyperthyroidism could be shown. Two types of hyperthyroidism could be defined directly: autonomous adenoma in cases of hot nodules in thyroid scan and Graves' disease, defined as hyperthyroidism with eye symptoms, and/or measurable TBII levels. The remainder, called "non-classifiable", included TBII negative Graves' patients, comprising of Hashitoxicosis, toxic nodular goiter, and other multifocal autonomies. 9.2% of the patients had an autonomous adenoma, 59.6% Graves' disease, and 31.2% unclassified hyperthyroidism. The main and significant difference between these types were mean age, goiter size, nodularity, and severity of the disease, being especially expressed in Graves' disease. Graves' patients had significantly increased T3/T4 ratios. Using as additional criteria diffuse regular uptake and/or increased T3/T4 ratios for immunogenic types of hyperthyroidism at least half of the 31.2% unclassified hyperthyroidism are probably Graves' disease. Forming two groups of iodine-deficient areas (IDA) and iodine-sufficient areas (ISA) according to the urinary iodine, it was possible to elucidate some characteristics independently of local factors. Autonomous adenoma was more frequent in IDA (10.1%) than in ISA (3.2%). Differences in iodine supply are reflected in the three types of hyperthyroidism by a significant higher prevalence of goiter, thyroid nodularity, lower thyroid hormone concentrations, and a higher rate of T3 toxicosis in IDA.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of serum T4 and T3 at the time of diagnosis in nosological types of thyrotoxicosis: a population-based study

“…In this study, comparing ten nosological types of thyrotoxicosis, GD patients presented the highest T 3 level and T 3 :T 4 ratio, which is in accordance with other studies (4,22,23,25). Similarly, amiodarone-associated thyrotoxicosis was dominated by high serum T 4 levels as previously reported by Martino et al (26).…”

“…Many studies have reported T 3 and T 4 levels in patients diagnosed with all types of thyrotoxicosis combined (20) or in a few (4,21,22,23) or even up to four nosological subtypes of thyrotoxicosis (24). In this study, comparing ten nosological types of thyrotoxicosis, GD patients presented the highest T 3 level and T 3 :T 4 ratio, which is in accordance with other studies (4,22,23,25).…”

“…before treatment was started (1). Aalborg Hospital Laboratory analyzed TSH by Immunoluminometric LUMItest from BRAHMS (Berlin, Germany), reference interval 0.3-4.5 mU/l; total T 4 and total T 3 by means of competitive RIA Amerlex-m T 4 4 reference interval 60-160 nmol/l, and T 3 reference interval 0.9-2.7 nmol/l. T 4 results above 300 nmol/l from this laboratory were recorded as O300 nmol/l (nZ18).…”

“…Thus, determinants for levels of serum T 3 and T 4 have not been studied in detail even if previous studies reported on various details such as influence of age (2,3), sex (3), iodine intake (4), and TSH receptor antibody (TRAb) concentration (5,6). Limited patient characteristics were included in most of these studies, and often they did not take various possible confounders into account, such as smoking, known to aggravate iodine deficiency (7) and to modulate thyroid autoimmunity (8), alcohol intake that besides from influencing the risk of Graves' disease (GD) (9) also may supply flavonoids known to modulate the selenodeiodinase activity (10), intake of vitamin supplements often containing iodine, and co-morbidity.…”

Epidemiology of subtypes of hyperthyroidism in Denmark: a population-based study

“…Other studies only evaluated certain age groups (8). Most studies were based on patients referred to hospital departments (6,(9)(10)(11)(12)(13)(14)(15)(16)(17)(18), potentially leading to referral bias (19).…”