Exp. Clin. Endocrinol. Vol. 97, No. 2/3, 1991, pp. 217-223

J. A. Barth, Leipzig

Department of Nuclear Medicine, University of Cologne/Germany

Differential Diagnosis of Hyperthyroidism

The causes of hyperthyroidism are diverse (Table 1). The first description by the german physician von Basedow (1840) and the american physician Graves (1940) refers to the classical form of hyperthyroidism: Morbus Basedow or Graves' disease. Today we know that Graves' disease is an autoimmune disease (Mann, 1989; Volpe, 1981). The other most common form of hyperthyroidism, seen primarily in areas of iodine deficiency, is associated with the name Plummer (1923). In the anglo-saxon literature toxic nodular goiter is the name given to this form. In Europe this non-immunogenic hyperthyroidism is called autonomy. Here we differentiate between unifocal, multifocal and disseminated autonomy (Bähre et al., 1988; Emrich and Bahre, 1978; Joseph, 1989). Autonomy is thought to be a maladaptation to iodine deficiency goiter (Emrich and Bahre, 1978). In recent years the pathogenesis of the development of autonomy has been clarified (Miller et al., 1964; Miller and Block, 1970; Studer et al., 1985, 1989), but the etiology is still obscure. Genetic factors are considered to be important, similar to their influence on the formation of iodine deficiency goiter. In the iodine deficiency region of West-Germany more than 90% of hyperthyroidism is due either to the immunogenic form (Graves' disease) or the non-immunogenic form (autonomy). The other causes of hyperthyroidism (see Table 1) are rare. Table 1

Different causes of hyperthyroidism.

Immunogenic

- Morbus Basedow - Graves' disease Non-immunogenic

- Plummer's disease - Toxic nodular goiter - Autonomy - Unifocal - Multifocal - Disseminated

Hyperthyroidism Factitious hyperthyroidism Transistor/destructive/-itis

- De Quervain - Silent, post partum - Hashimoto - Radioiodine Pituitary

- Adenoma/TSH - Central resistance Metastases of differentiated Thyorid carcinoma Paraneoplastic

- Hydatid mole - Chorionepithelioma - Seminoma

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H. SCHICHA

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Exp. Clin. Endocrinol. 97 (1991) 2/3

Criteria for the Differentiation between Immunogenic and Non-Immunogenic Hyperthyroidism (Graves' Disease versus Autonomy)

The cardinal symptoms and signs of hyperthyroidism are shwon in 'Täble 2. Von Basedow (1840) described his 4 patients so perfectly that even modern text books are not able to elaborate very much further. In many cases the history alone allows the establishment of a provisional diagnosis. In more than half of the patients diagnosis can be made

at first sight because of exophthalmos. It is characteristic of Graves' disease that the clinical symptoms are distinct and typical. In German literature the "Merseburger Trias" defines the typical combination of exophthalmos, goiter and tachycardia. läble 2 Symptoms and signs in immunogenic (Morbus Basedow, Graves' disease) and non-imHyperthyroidism Morbus Basedow

Autonomy

Eye symptoms Goiter làchycardia Increased appetite Loss of weight

Weakness

Diarrhea Sweating Feeling of warmth 'fremor Agitation

Loss of appetite Loss of weight Apathy Depression lächycardia Arrhythmia Dyspnea Complete picture of the disease

Usually typical "Merseburger THas"

Usually atypical "Apathetic"

"Non-activated" "Altershyperthyreose"

In contrast hyperthyroidism associated with autonomy presents atypically. The presence of few symptoms or signs may lead to the diagnosis of tumor, heart disease or mental illness rather than the correct diagnosis. Thyroid autonomy with hyperthyroidism in the elderly is often missed, but may be associated with severe toxicosis and occasionally even has a lethal outcome (Köbberling et al., 1981). It is commonly induced by accidental increased iodine intake either as an iodine containing drug or as X-ray contrast material (Schicha et al., 1980).

In the 70s, especially in West Germany the existence of iodine induced hyperthyroidism in the elderly was widely denied. The aims of our study, started in the early 80s, were to identify the tests which allow differentiation between Graves' disease and autonomy and to clarify the role of iodine intake as a precipitating factor (Schicha and Emrich, 1983). At that time tests for thyroid microsomal antibodies (MAB) and thyroglobulin antibodies (TAB) were commercially available. The starting point for the study was the hypothesis that eye symptoms are only associated with immunogenic hyperthyroidism.

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munogenic (autonomy) hyperthyroidism.

219

H. ScHICRA, DD of Hyperthyroidism

In 326 patients with hyperthyroidism and without a solitary hot nodule on scm-

lhble 3 Frequency of secondary criteria in patients classified as IM-HY or NIM-HY on the basis of eye signs and antimicrosomal antibodies.

= endocrine ophtalmopathy, MAB = antimicrosomal thyroid antibodies, = positive, + 0 = negative EO

Age >50 years No palpable goiter Nodular goiter Scan non-homogeneous Iodine contamination

Endocrine orbitopathy MAB positive

EO+

EO0

(N = 105)

MAB 0 (N = 121)

34°/o 33°/o 21°/o

71% 9°/o

10°/o 16°/o

55% 61% 82%

IM-HY

NIM-HY

59% 96%

18°/o

0%

p