Lethargy and sluggishness

This page is reference information compiled from the cited sources. It is not medical advice. For any decision about health, diagnosis or care, consult a qualified professional.

What it is

Lethargy and sluggishness are symptoms associated with hypothyroidism. Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as extreme fatigue. In older children and adolescents, the symptoms of hypothyroidism may include fatigue and sleepiness. People with hypothyroidism often have no or only mild symptoms. Numerous signs and symptoms are associated with hypothyroidism and can be related to the underlying cause, or a direct effect of not having enough thyroid hormones.

Key facts

Extreme fatigue is listed as a symptom caused by hypothyroidism. In older children and adolescents, the symptoms of hypothyroidism may include fatigue and sleepiness. Many symptoms of hypothyroidism are otherwise common and do not necessarily indicate thyroid problem. Hypothyroidism is more common in women than in men. People over the age of 60 are more commonly affected. The diagnosis of hypothyroidism, when suspected, can be confirmed with blood tests measuring thyroid-stimulating hormone and thyroxine levels. Thyroid hormone is required for the normal functioning of numerous tissues in the body. Not enough thyroid-stimulating hormone can decrease thyroid hormone production.

When to seek professional help

The source text associates professional care with the diagnosis of hypothyroidism when it is suspected. The diagnosis can be confirmed with blood tests. Myxedema coma is a rare but life-threatening state of extreme hypothyroidism that may occur in those with established hypothyroidism when they develop an acute illness. Myxedema coma can be the first presentation of hypothyroidism. Hypothyroidism when untreated may lead to infertility and an increased risk of miscarriage or infant death around the time of birth, mostly in severe cases. Not treating infants may lead to an intellectual impairment.

Source: Hypothyroidism (CC BY-SA 4.0 (Wikipedia)), retrieved 2026-09-24.