Dysthyroidism in Elderly Subjects

Introduction: Aging is associated with an anatomical and functional hetero-geneity of the thyroid which varies according to the iodized status. The aim was to describe the clinical, etiology and therapeutic profile of dysthyroidism in elderly subjects in the internal medicine at the Abass Ndao University Hospital. Patients and methods: This was a retrospective, descriptive and analytical study, including all subjects aged 60 and over followed from January 1, 2010 to December 31, 2019 (10 years) for thyroid disease. Results: 371 Patients were collected with a prevalence of 3.8%. The sex ratio was 0.15 and the mean age was 65.3 years. The circumstances of discovery of the disease were a grade 2 - 3 goiter (62.5%), exophthalmos (24.5%), thyrotoxicosis (56.6%), a symptom of low metabolism (5.4%), a cervical compression (10.8% including 8% of dysphasia), and a cardiothyreosis (9.4%). It was hyperthyroidism (65.2%), and hypothyroidism (7.2%). The main etiologies were toxic multinodular goiter (33.2%), Graves’s disease (29.6%), euthyroidism nodular goiter (26.8%),


Introduction
Aging is a physiological process that is associated with anatomical and functional changes in the body. These non-enzymatic molecular alterations of proteins lead to an alteration of their structural and functional properties. This phenomenon participates in cell and tissue aging and, therefore, in the general aging of the organism [1]. It has been shown that aging is associated with exhaustion of most of the hormonal and enzymatic secretory functions [2]. This exhaustion is due to a loss of protein activity after glycation or carbamylation [3]. Endocrine functions in general and especially thyroid gland are not immune to this upheaval.
Thyroid pathology is the most common endocrinopathy in the elderly. Aging is associated with complex changes in thyroid function that occur at several levels of regulation. The secretion of thyroid hormones is generally within the lower limits of the usual values. The two most significant changes are the shift in the distribution of the thyroid-stimulating hormone (TSH) to higher values, resulting in an increase in the upper limit of normal TSH levels from 4.5 to 6 µUI/mL after 70 years and 7.5 µIU/mL after 80 years. Thyroid pathologies affecting the anatomy (goiter, nodules, cancer) or the function (hyperthyroidism or hypothyroidism) of the thyroid are frequent especially in the elderly [4]. In the event of dysthyroidism, it remains in general rough or masked by the symptoms related to aging. The phenomena of aging and these anatomical consequences mean that diagnosis is not always easy, in a geriatric context [2]. These considerations have motivated this retrospective work, which aims to determine the clinical, biological and progressive characteristics of dysthyroidism in the elderly at the Abass Ndao hospital center.

Patients and Methods
It was a retrospective, descriptive study conducted from January 1, 2010 to December 31, 2019 (10 years). The study was carried out at Clinique Médicale II at the Center Hospitalier University of Abass Ndao. It focused on subjects aged 60 and over with thyroid disease and followed in internal medicine. Patient records were used to supplement data useful for the study. Incomplete clinical and/or biological records were not included. The pre-established sheet which served as the basis for the collection related to the following elements: -Epidemiological and clinical aspects: Age, gender, other associated pathologies, time limit of the consultation. The goiter was classified into 4 grades according to the classification of the World Health Organization [5]. Graves's orbitopathy was characterized according to the consensus of the European Group on Graves Orbitopathy [6]. We also looked for other clinical manifestations of  The diagnosis of nodular goiter was retained in the presence of single nodular formation (single nodule) or multiple nodule (multinodular goiter) on a normal or enlarged thyroid gland. Goiter was toxic nodular in front of a nodular goiter associated with hyperthyroidism. In this specific case, thyroid scintigraphy confirmed the toxic nature of the nodule identified on ultrasound. In case of thyroid nodule, a needle aspiration with a histological study was requested. Other explorations such as blood sugar, hemogram, liver function, EKG were requested according to the clinical profile. The diagnosis of cardiothyreosis is based on the presence of the association of thyrotoxicosis and various cardiovascular disorders such as heart failure, coronary artery disease, rhythm or conduction disorders.
-Treatment and evolution of thyroid pathology: We studied the treatment carried out. These were mainly medical treatment (synthetic antithyroid or L-thyroxin or anti inflammatory), surgery, radioactive iodine and abstention from therapy.
The course of thyroid disease was also assessed.
-Data analysis: For the descriptive part, the data were presented as a percentage for the qualitative variables and as an average for the quantitative variables.
The data entry and processing was carried out by software Epi info version 7.2.2.2.

Epidemiological Aspects
We included 371 patients out of 9750 cases of dysthyroidism received in 10 years.
The prevalence was of 3.8%. The female gender was predominant (321 women) with a sex ratio of 0.15. The mean age was 65.3 years (range 60 and 90). The other associated pathologies were 76 cases of arterial hypertension (20.5%), 15 cases of diabetes mellitus (4%). The average time limit of consultation was 29.8 months (range 6 and 120 months).

Clinical Aspects
The circumstances of diagnosis of thyroid disease were mainly a goiter (291 cas- and myxedematous syndrome (5 cases, 1.3%). Among the 35 subjects with cardiothyreosis, 25 cases (6.7%) had a rhythm and conduction disorder. Table 1 shows the epidemiological and clinical profile of dysthyroidism in the elderly.  Table 2 shows the functional and etiological profile of dysthyroidism.

Paraclinical and Etiological Aspects
The sex ratio and the average age of the patients were respectively of (0.  Two cases of death were recorded in connection with cardiothyreosis.

Discussion
In Africa, few works have been interested in thyroid pathology in the elderly. Most of them were limited to a characterization specific to hypothyroidism or hyperthyroidism [7]. This explains the absence of comparative epidemiological data. A South African study reported frequencies ranging from 0.4% to 9% [8].
Elsewhere in Europe and the United States, the prevalence of dysthyroidism in the elderly varies according to country, series, iodine status and diagnostic methods [9]. This difference could be explained by the existence of geriatric units, through greater accessibility and sometimes a systematization of biological explorations in the elderly European population. In our study the predominance was female and the average age around the sixth decade. In Europe, the average age was at the seventh or even the eighth decade [10] [11].
In the elderly, due to senescence, a number of symptoms are masked or absent during dysthyroidism [12]. The diagnoses are made thanks to the dosage of TSH recommended in first intention to evaluate the thyroid function. In the elderly, the assay can be performed as part of the overall assessment of cognitive impairment or dementia or in the presence of clinical signs suggestive of dysthyroidism. This last indication can be relatively broad, justified by the differences reported in the clinical expression of dysthyroidism proven after 70 years [13] [14]. In most cases series, the symptoms are summed up as specific signs of the disease or the complications that preferentially affect the heart and the brain [15] [16]. In our study, the most common signs were goiter (78.4%), exophthalmos (24.5%), cervical compression (10.8%) and cardiothyreosis (35 cases, 9.4%).
On the functional level, we find in an English study 92.3% of euthyroidism, 0.3% to 1% of hyperthyroidism and 0.3% to 6.2% of hypothyroidism [10]. In a summary work reported by Retomaz et al. [9], the prevalence of true hypothyroidism was from 0.5% to 7.6%. We report 7.2% of hypothyroidism cases. As in our series, Hashimoto's disease remains the predominant aetiology [9]. With the gradual onset of hypothyroidism, the symptoms may be difficult to assess. Several classic signs of hypothyroidism can be attributed to aging. Finally, Hypothyroidism can be associated with cardiovascular dysfunction and especially with an increased risk of atherosclerosis [17]. In our series, no case of cardiac complications related to hypothyroidism was found.
Graves's disease and especially toxic nodular goiter constitute the two main etiologies of hyperthyroidism [18]. According to Retomaz et al. [9], the prevalence of hyperthyroidism is 0.02% to 2.5% after 60 years. The two most common causes are toxic nodule and multinodular goiter in regions with iodine deficiency, and Graves' disease in regions with normal or high iodine status. Cardiac manifestations are not uncommon [19]. They are often in the foreground with complications such as atrial fibrillation and heart failure [20].  [21]. In subjects with multinodular goiter, there is a risk of progression to hyperthyroidism due to the autonomy of one or more nodules. Among our 247 patients with nodular goiter, 59.5% had true hyperthyroidism. In our study, 02 papillary thyroid carcinomas were diagnosed on multi-nodular goiter. Papillary carcinomas were more common in solitary nodules of the thyroid in the elderly.
The treatment of hyperthyroidism is preferably radical in the elderly to avoid the risk of recurrence with cardiac repercussions, the effects of which can be deleterious at an advanced age. It can be surgery or iodine therapy 131. The prescription of synthetic antithyroid drugs is limited to a short period for the return to euthyroidism before radical treatment [22].

Conclusion
Dysthyroidism in the elderly is characterized by clinical and progressive variability. The etiologies were mainly dominated by 3 main entities: Graves' disease, nodular goiter, autoimmune thyroiditis. The deaths found were mainly related to cardiovascular complications which were the prerogative of hyperthyroidism.
There was no correlation between the type of goiter and the histological nature of the neoplasias found. A prospective study on a larger scale in the population could allow deciding on the best profile of thyroid pathology in Senegal.

Limitations of the Study
The study was conducted in university hospital. It may not represent the community situation which is important in terms of knowledge and practice.
This is a single center study. Large scale multicenter study is needed to represent the national situation.
This is a retrospective study conducted from patient's files. Only the complete files were included which makes a loss of data.
This kind of work doesn't require in our country the approval of ethic committee because it is a retrospective work on patient's file.

Conflicts of Interest
The authors have nothing to disclose.