Vitiligo and Hashimoto’s Thyroiditis

The study of diseases associated with vitiligo is an activity of great importance in the path toward increasingly effective treatments. The analysis of comorbidities in fact reveals valuable information regarding certain conditions, particularly those of an autoimmune nature. Among the diseases associated with vitiligo is Hashimoto’s thyroiditis, also known as chronic Hashimoto’s thyroiditis, a disorder that causes inflammation of the thyroid gland.

Studies Demonstrating the Comorbidity Between Vitiligo and Hashimoto’s Thyroiditis

The most authoritative studies suggest that worldwide the prevalence of Hashimoto’s thyroiditis in patients affected by vitiligo is approximately 5% (study: The prevalence of thyroid disease in patients with vitiligo)

This percentage rises to 20% when thyroiditis is investigated more thoroughly, considering the presence of anti-thyroglobulin and anti-thyroid peroxidase antibodies, as suggested by the article Anti-thyroid peroxidase antibody and vitiligo: a controlled study.

The percentage rises even further (27.6%) when considering the results contained in Dr. Giovanni Menchini’s specialization thesis, developed for the University of Siena in 2001.

However, in order to obtain more meaningful data, it is important to differentiate the population being considered. For example, we now know that Hashimoto’s thyroiditis, like almost all autoimmune phenomena, predominantly affects women, usually after the age of 40. Likewise, we have come to understand that women over the age of 45 affected by vitiligo have a 50% probability of also having Hashimoto’s thyroiditis.

This information is important because thyroid dysfunctions of autoimmune origin (such as Hashimoto’s thyroiditis) often do not present clearly identifiable symptoms, but only small alterations that, without specific blood tests, could go unnoticed and consequently create significant physical problems.

For this reason, during the initial consultation, particular attention is paid to the blood test values that may indicate thyroid diseases: complete blood count with differential, anti-thyroglobulin and anti-thyroid peroxidase antibodies, TSH, FT3, and FT4.

What Is Hashimoto’s Thyroiditis?

Hashimoto’s thyroiditis owes its name to Hakaru Hashimoto, a Japanese physician who first identified this disease during the first decade of the twentieth century. While working as a medical examiner performing autopsies, he observed the presence of thyroid inflammations, often of minor significance, which he identified as autoimmune thyroiditis.

In many cases, chronic thyroiditis is associated with other autoimmune diseases, either organ-specific or non-organ-specific; in addition to vitiligo, these include chronic atrophic gastritis, pernicious anemia, autoimmune hemolytic anemia, hypoparathyroidism, type 1 diabetes, and celiac disease.

The Characteristics of Hashimoto’s Thyroiditis

Hashimoto’s thyroiditis is an autoimmune disease that results in an inflammatory process affecting the thyroid gland. In most cases, it is a condition without easily detectable symptoms; however, the consequences are progressive and irreversible and may be linked to reduced thyroid function, to the point where thyroid hormone production becomes insufficient and a condition of hypothyroidism can fully develop.

Hashimoto’s thyroiditis is the most widespread thyroid disease and represents the leading cause of hypothyroidism in areas of the world where iodine intake is sufficient.

Iodine is in fact an essential element for natural growth and the well-being of the human body. It is estimated that approximately 80% of the iodine consumed by the human body is “captured” by the thyroid gland, which uses it to produce thyroxine and triiodothyronine, two hormones that are extremely important in regulating cellular metabolism and vital functions.

The World Health Organization has estimated the daily iodine requirement for an adult at 150 mcg, increasing to 200 mcg per day during pregnancy and breastfeeding. Children under one year of age require at least 50 mcg per day, while for children aged 1 to 10 years the requirement ranges between 90 and 120 mcg per day.

Among women, the incidence of Hashimoto’s thyroiditis is 3.5 cases per 1,000 inhabitants, a figure that decreases when considering the male population (0.8 per 1,000 inhabitants).

Clinical Manifestations of Hashimoto’s Thyroiditis

In subjects affected by Hashimoto’s thyroiditis, the appearance of goiter is common — the classic swelling located in the neck area that in the past directly identified thyroid diseases. Goiter generally develops gradually and without causing pain or other discomfort to the patient.

Although the autoimmune destruction process of the thyroid should lead to thyroid atrophy (therefore a reduction in its size), the evolution of goiter toward an atrophic state is not particularly common.

From a functional point of view, Hashimoto’s thyroiditis may evolve into different situations:

• Normal thyroid function
• Subclinical hypothyroidism
• Clinical hypothyroidism
• Transient hyperthyroidism/thyrotoxicosis

The Evolution of Hashimoto’s Thyroiditis

The analysis of scientific literature suggests an evolution characterized by slow progression toward a condition of clinical hypothyroidism, with a higher percentage in men compared to women. However, many additional factors may interfere with the course of the disease, thereby influencing its evolution.

Patients affected by Hashimoto’s thyroiditis usually do not present any symptoms. The only sign of the disease’s onset is the appearance of swelling in the neck area, commonly referred to as goiter. In patients who have had the disease for a long time, the typical symptoms of hypothyroidism may appear. In a small percentage of patients, hyperthyroidism may also occur (a condition also referred to as Hashitoxicosis, or thyrotoxicosis), caused by the production of thyroid hormones by the already damaged thyroid gland. On rare occasions, subjects affected by Hashimoto’s thyroiditis present ophthalmopathy similar to that associated with Graves’ disease.