Hashimoto's Disease

Named after Hakaru Hashimoto (1881 to 1934) , japanese pathologist
Synonymes: Autoimmune thyroiditis type 1A, Autoimmune thyroiditis type Typ 2A
German: Hashimoto-Thyreoiditis

	Table of contents
	1. Definition 2. Etiology and Pathogenesis 3. Classification 3.1. ...according to thyroid volume 3.2. ...according to metabolic state 4. Diagnosis 5. Symptoms 6. Therapy 7. Prognosis

Definition

Hashimoto's disease refers to an autoimmune disease of the thyroid (Autoimmune Thyroiditis). This entity has been first descibed by the japanese surgeon and pathologist Hakaru Hashimoto in the year 1912 in Berlin.

Etiology and Pathogenesis

The disease is characterized by a destruction of thyroid tissue that is caused by different cellular and humoral immune processes. While detailled trigger mechanisms are still unknown it has become clear that formation of microsomal antibodies against thyroid peroxidase (TPO-AB) and of antibodies against thyroglobulin (Tg-AB) plays a critical role. These antibodies precipitate impaired thyroid function.

A small percentage of Hashimoto patients seems to be antibody negative.

Classification

...according to thyroid volume

• atrophic form: continuous decrease in thyroid volume (distinguishable from primary atrophic Ord's disease)
• hypertrophic form: Increase of thyroid volume with development of goiter

...according to metabolic state

• Autoimmune thyroiditis type 1A: Euthyroidism
• Autoimmune thyroiditis type 2A: Hypothyroidism

Diagnosis

Diagnostical criteria for Hashimoto's disease are:

• Increased thyroid volume (normal: 15 to 18 mL in females, 20 to 25 mL in males)
• hypoechogenic pattern in ultrasonography
• Reduced Technetium-Uptake (TcTU) in thyroid scintigraphy
• Positive Tg-AB and/or TPO-AB.

Symptoms

Symptoms of Hashimoto's disease are varying and ambiguous. A fraction of the cases shows abortive course or proceeds with very few symptoms being easily treated by substituting thyroid hormones. Another fraction is associated with complications including Hashimoto's encephalopathy as well as manifold and deceptive symtoms.

Typically, a short phase of thyrotoxicosis (Hashitoxicosis) in the beginning of the disease is replaced by hypothyroidism in later phases.

Therapy

There is no evidence for an effective activity of immunosuppressive angents.

Therapy consists in normalizing plasma levels of thyroid hormones. Hypothyroidism is treated with life-long substituting levothyroxine. Selenium may help to reduce antibody levels.

Prognosis

Hashimoto's disease doesn't heal up why it requires life-long substitution with T4. The disease may sometimes be associated with cervical lymphomas. Therefore regular investigation of neck and thyroid via ultrasonography is recommended.