The Role of Thyroid and Parathyroid Metabolism Disorders in the Etiology of Sudden Onset Dizziness

Background

Dizziness is one of the most common clinical complaints among patients who are referred to the Emergency Department (ED); it has both benign and serious etiologies and affects 20–30% of the general population. Approximately 2.6 million people who suffer from dizziness visit the ED annually in the USA [1]. There are tremendous costs associated with managing dizziness, mainly due to delayed diagnosis, and 86% of patients experience significant disruption in their daily activities [2]. Because dizziness is a symptom of many disorders, clinicians are often faced with difficulty in formulating a definitive diagnosis and effective symptom management [3]. Metabolic disorders are recognized by most authors as a source of balance disorders. Some endocrine diseases, such as hypothyroidism, may lead to balance disorders and can cause dizziness by affecting the vestibular system labyrinthine functions [4,5].

Early discovery of the etiology of dizziness can optimize the diagnosis and symptom management for patients, thereby decreasing costs, ED crowding, and visits to the ED. To date, there has been inadequate research to systematically investigate thyroid and parathyroid function disorders as etiologic factors for sudden onset dizziness (SOD) in patients presenting to the ED.

We examined whether thyroid and parathyroid function disorders played a role in patients who are referred to the ED with complaints of SOD.

Material and Methods

STUDY DESIGN:

This study was conducted between in August 2013 and February 2014 at the Adiyaman University Medical Faculty Education and Research Hospital ED with the approval of the ethics committee (date/number: 05.02.2013/01-1.1). The study was performed prospectively with 100 SOD patients who experienced their first incidence of SOD. The patients were consecutively referred to the ED, complaining of dizziness that was diagnosed as SOD.

After the patients provided informed consent, a 5-mL sample of venous blood was obtained from the antecubital area of the arm before administering the treatment. Blood samples were studied with the Immulite 2000 analyzer using the chemiluminometric method, measuring serum levels of fT3 (range 1.8–4.6 pg/mL), fT4 (range 0.93–1.7 ng/dL), TSH (range 0.27–4.2 mIU/mL), anti-thyroglobulin antibody (anti-Tg) (range 0–7 IU/mL), antithyroperoxidase antibody (anti-TPO) (range 0–35 IU/mL), parathormone (PTH) (range 12–72 pg/mL), and serum calcium ([Ca²⁺]) (range 8.6–10.2 mg/dL). The serum [Ca²⁺] values were calculated in association with the serum albumin levels. Overt hypothyroidism was defined as elevated serum TSH levels with decreased serum fT3 and fT4 levels with presence of clinical signs of hypothyroidism. Subclinical hypothyroidism was defined as elevated serum TSH levels with normal serum fT3 and fT4 levels without clinical signs of hypothyroidism, or normal serum TSH levels with elevated serum fT4 levels without clinical signs of hypothyroidism. Overt hyperthyroidism was defined as decreased serum TSH levels with elevated serum fT3 and fT4 levels with together clinical signs of hyperthyroidism.

All detailed thyroid and parathyroid gland examinations and ultrasound imaging were performed by a general surgeon and a radiologist, respectively. According to thyroid ultrasonography, findings of tissue echogenicity of thyroid gland were divided into 3 categories: isoechogenic, hypoechogenic, and hyperechogenic.

Adult patients who experienced their first attack of SOD and presenting to the ED were included into study. The patients with SOD who had 1 or more of following disease conditions were excluded from study: undergoing thyroid surgery, any thyroid and parathyroid gland disease patients with any central and peripheral dizziness attacks before time, receiving some drugs affecting thyroid functions such as glucocorticoids, antipsychotics, oral contraceptives and proton pump inhibitors, and the patients who did not wish to participate in the study.

STATISTICAL ANALYSIS:

National epidemiologic prevalence data were used to determine the frequency distribution of thyroid metabolism disorders. The general prevalence of thyroid metabolism disorders (TMD) and hyperparathyroidism are 3.4% and 0.03%, respectively, in Turkey [6,7]. The 1-sample z test was used to determine whether the hypothesized population proportion differed significantly from the observed sample proportion. NCSS v1.12 was used for the statistical data analysis. A p value of <0.05 was considered statistically significant.

Results

A total of 100 patients were included in this study; 37% (n=37) were female, and 63% (n=63) were male. The mean age was 39 years old (19–69, SD±12, 38). The average values of TSH, fT3, fT4, and PTH are shown in Table 1. The results were: 2% (n=2) of the patients had elevated serum TSH levels with decreased serum fT3 and fT4 levels (overt hypothyroidism), 2% (n=2) had elevated serum TSH levels with normal serum fT3 and fT4 levels (subclinical hypothyroidism), 4% (n=4) had normal serum TSH levels with elevated serum fT4 levels (subclinical hypothyroidism), and 2% (n=2) had decreased serum TSH levels with elevated serum fT3 and fT4 levels (overt hyperthyroidism) (Table 2 and Figure 1). A total of 10% (n=10) of patients had TMD; this result was statistically significant compared with the general population prevalence (P=0.02) (Figure 2). Two percent (n=2) of the patients had elevated parathormone levels with elevated serum [CaP2+] levels, which were statistically significant compared with the general population prevalence (P=0.00) (Figure 3). Four percent (n=4) of the patients had corrected serum [Ca2+] levels that were lower than the normal serum range. Thyroid gland ultrasound examinations showed that 28% (n=28) of the patients had multinodular goiters, 2% (n=2) had thyroiditis, 12% (n=12) had an isolated unilateral nodule, and 58% (n=58) had normal thyroid gland tissue (Figure 4). The anti-thyroglobulin and anti-topoisomerase levels were normal in all participants.

Discussion

LIMITATIONS:

In our study, instead of a control group, the use of national prevalence data was preferred to compare study findings. The relationships between thyroid and parathyroid gland ultrasound findings and dizziness are not discussed here. Additionally, hyperthyroidism and hyperparathyroidism etiologic factor analyses were not conducted longitudinally.

Conclusions

Thyroid and parathyroid disease play a role in dizziness etiology in different ways. We observed that TMD has a higher prevalence in SOD patients than in the normal population. Thus, detailed neck examination, TFT, and thyroid ultrasound examination should be routinely performed to provide a quick diagnosis and proper treatment for a patient who is admitted to the ED with SOD.