Hypothyroidism

Overview

Hypothyroidism is a common endocrine condition in which the thyroid gland does not produce enough thyroid hormones for the body’s needs. The thyroid is a small, butterfly-shaped gland located at the front of the neck. Its hormones help regulate metabolism, body temperature, heart function, digestion, energy levels and many other body processes.

When thyroid hormone levels are low, many functions in the body may slow down. Symptoms can develop gradually and may be mild at first, so hypothyroidism is sometimes difficult to recognize without blood tests. The condition can affect adults of any age, and it is more common in women and older adults. It can also occur during or after pregnancy, and in children, although the signs may differ by age.

With appropriate medical assessment and ongoing monitoring, hypothyroidism can usually be managed effectively. Treatment aims to restore thyroid hormone levels to a healthy range and reduce symptoms, while avoiding over-treatment.

Symptoms

The symptoms of hypothyroidism can vary from person to person. Some people have only subtle changes, while others experience several symptoms. Common symptoms may include:

• Tiredness, low energy or increased sleepiness
• Weight gain or difficulty losing weight
• Feeling unusually cold
• Dry skin, brittle nails or hair thinning
• Constipation
• Slow heart rate
• Muscle aches, stiffness or joint discomfort
• Low mood, reduced concentration or memory problems
• Hoarse voice
• Puffy face or swelling around the eyes
• Irregular or heavier menstrual periods
• Reduced fertility in some cases

In infants and children, untreated hypothyroidism may affect growth and development. In older adults, symptoms may be less typical and can sometimes be mistaken for other health problems.

Causes and Risk Factors

Hypothyroidism can have several causes. One of the most common is an autoimmune condition in which the immune system mistakenly attacks the thyroid gland, reducing its ability to make hormones. Other possible causes include previous thyroid surgery, radiation treatment to the neck area, certain medical treatments, iodine imbalance, inflammation of the thyroid and disorders affecting the pituitary gland, which helps control thyroid hormone production.

Risk factors that may increase the likelihood of hypothyroidism include:

• Being female
• Older age
• A family history of thyroid disease or autoimmune disease
• Personal history of autoimmune conditions
• Previous thyroid surgery or neck radiation
• Pregnancy or the period after childbirth
• Use of certain medications that can affect thyroid function
• Previous abnormal thyroid blood tests

Having one or more risk factors does not mean a person will definitely develop hypothyroidism. However, it may help a doctor decide when thyroid testing is appropriate.

Diagnosis

Diagnosis is based on a medical evaluation and blood tests. A doctor will usually ask about symptoms, medical history, family history, pregnancy status, previous treatments and medications. A physical examination may include checking the neck for thyroid enlargement, assessing heart rate, skin changes, reflexes and other signs that may suggest thyroid hormone imbalance.

The main blood tests measure thyroid-stimulating hormone and thyroid hormone levels. Thyroid-stimulating hormone is produced by the pituitary gland and signals the thyroid to work. In many cases of hypothyroidism, thyroid-stimulating hormone is higher than expected because the body is trying to encourage the thyroid to produce more hormone. The doctor may also request thyroid antibody tests to look for autoimmune thyroid disease.

Sometimes results are borderline or show “subclinical” hypothyroidism, meaning blood tests are abnormal but symptoms may be mild or absent. In these cases, the doctor may repeat testing and consider age, symptoms, pregnancy plans, heart health and other factors before recommending management.

Treatment Options

Treatment depends on the cause, severity, symptoms, age, pregnancy status and other medical conditions. The most common treatment is thyroid hormone replacement, taken as prescribed by a doctor. The goal is to bring thyroid hormone levels back into the appropriate range for the individual patient.

Blood tests are used to monitor response to treatment and to adjust the amount if needed. It may take time to find the most suitable level, and regular follow-up is important. Taking more thyroid hormone than needed can cause problems such as palpitations, nervousness, sleep disturbance or effects on bone and heart health, so treatment should be supervised by a healthcare professional.

Some people may not need immediate hormone replacement, especially if the condition is mild and there are no symptoms. In such cases, careful monitoring may be recommended. Pregnant patients, people planning pregnancy, children and individuals with heart disease may require more specific assessment and follow-up by an endocrinologist or other qualified physician.

Lifestyle measures such as a balanced diet, regular activity, adequate sleep and management of other health conditions can support general well-being, but they do not replace medical treatment when thyroid hormone replacement is needed. Supplements or high-iodine products should not be used without medical advice, as they may worsen some thyroid conditions.

When to See a Doctor

Medical advice should be sought if symptoms such as ongoing fatigue, unexplained weight changes, cold intolerance, constipation, hair thinning, menstrual changes, low mood or neck swelling are present, especially if they persist or worsen.

People with a family history of thyroid disease, autoimmune disease, previous thyroid treatment, pregnancy or plans for pregnancy should discuss whether thyroid testing is appropriate. Anyone already diagnosed with hypothyroidism should attend regular follow-up appointments and report new symptoms, pregnancy, major weight changes or changes in other medications.

Urgent medical care is needed if a person with known or suspected severe hypothyroidism develops extreme drowsiness, confusion, very low body temperature, breathing difficulty, severe weakness or loss of consciousness. These symptoms are uncommon but may indicate a serious medical emergency.