Hypothyroidism — Underactive Thyroid Symptoms and Treatment

What Is Hypothyroidism?

Hypothyroidism, also known as underactive thyroid, is a condition where the thyroid gland does not produce enough thyroid hormones — T3 and T4 — leading to a generalised slowing down of metabolic processes throughout the body.

The thyroid is a butterfly-shaped gland in the lower front of the neck. Its hormones are carried in the blood to every tissue, where they set the pace at which cells use energy. When production falls, that pace drops everywhere at once: the heart beats more slowly, the gut moves more sluggishly, heat production falls, and mental processing slows.

This is one of the most common endocrine conditions, and one of the most treatable. It is also one where symptoms accumulate so gradually that people frequently attribute years of fatigue and weight gain to age, stress or workload before the diagnosis is made.

Symptoms

Symptoms vary between individuals depending on the magnitude of the hormone deficiency and how long it has been present. Common features include:

• Constipation
• Fatigue and weakness — not relieved by rest
• Weight gain
• Hair loss
• Dry skin
• Intolerance to cold
• Menstrual disturbances
• Depression and low mood

Untreated long-term cases can also present with a goitre — a swelling in the front of the neck as the gland enlarges under continuous stimulation.

The symptoms people miss — voice, swallowing and hearing

Three further symptoms deserve particular emphasis, because they are common, frequently overlooked, and often the reason a patient arrives at an ENT clinic rather than a physician's:

Hoarseness of voice. When thyroid hormone levels are very low and left uncorrected, the vocal folds develop a gelatinous thickening of their vibrating layer — a state called myxoedema. Thickened vocal folds cannot vibrate as freely, producing a low, harsh, "smoker's voice" quality. It develops gradually, and patients often do not notice until someone else remarks on it. In most cases it improves once hormone levels are corrected, though severe long-standing cases occasionally need further intervention.

Oedema and swallowing difficulty. The same tissue changes cause generalised puffiness, particularly around the face and eyes. Where hypothyroidism is accompanied by a goitre, the enlarged gland can press backward on the oesophagus and produce genuine difficulty swallowing, or a persistent sensation of a lump in the throat.

Hearing difficulty. Fluid and tissue changes can affect the middle ear and eustachian tube, causing a blocked sensation and mild hearing loss that resolves once thyroid function is restored.

Because these overlap with reflux, globus sensation and other throat conditions, thyroid function testing is a reasonable step in anyone presenting with unexplained hoarseness or throat discomfort.

Causes

Some of the causative factors of hypothyroidism are:

• A family history of autoimmune thyroid disease, such as Hashimoto's thyroiditis — an autoimmune condition that harms thyroid cells. This is the most common cause where iodine intake is adequate
• An injury to the thyroid, or surgical removal of the gland — see thyroidectomy
• The use of radioactive iodine therapy, a treatment for hyperthyroidism
• Inflammation of the thyroid gland
• Medications containing lithium or iodine

Who Is at Risk

A number of factors increase the risk of developing hypothyroidism:

• Being female
• Being of an older age
• Family history of Hashimoto's thyroiditis or any other autoimmune disease
• Personal history of an autoimmune disease — adrenal insufficiency, rheumatoid arthritis, or type 1 diabetes
• Being pregnant or postpartum
• Too much or too little iodine consumption
• Having received radiation to the neck or upper chest
• Treatment with certain medications, for example lithium for bipolar disorder

How Hypothyroidism Is Diagnosed

Hypothyroidism is diagnosed with a blood test. People with a TSH level above the normal range, together with lowered levels of thyroid gland hormones, are considered to have hypothyroidism.

The logic is worth understanding, because it explains why TSH is the headline number on your report. The pituitary gland monitors circulating thyroid hormone continuously. When it detects a fall in T4, it increases its output of thyroid-stimulating hormone (TSH) to drive the thyroid harder. So a rising TSH is the earliest signal that the thyroid is struggling — often before T4 has fallen below the normal range at all.

Where the cause needs clarifying, thyroid antibody testing identifies Hashimoto's thyroiditis, and an ultrasound assesses the size and texture of the gland — particularly if a lump is felt during neck examination, in which case thyroid nodule evaluation follows its own pathway.

Treatment

Synthetic thyroxine (T4) supplementation is the treatment of choice. The goal of treatment is to supplement thyroid hormone and normalise TSH levels in the body.

The dosage of thyroxine depends on:

• Age
• The individual requirement
• The severity of the deficiency
• The duration of hypothyroidism

TSH should be measured every 2–3 months to assess the adequacy of supplementation, until a stable dose is established. After that, monitoring typically moves to annual or six-monthly checks, with more frequent testing during pregnancy or after significant weight change.

Two practical points make a substantial difference to how well treatment works:

Take it on an empty stomach. Thyroxine is absorbed poorly in the presence of food. Take it first thing in the morning with plain water, and wait 30–60 minutes before eating or drinking tea or coffee.

Separate it from calcium and iron. These bind thyroxine in the gut and block absorption. Leave a gap of at least four hours between your thyroxine and any calcium or iron supplement.

Treatment is generally lifelong. A normal TSH means the current dose is working — not that the condition has resolved — so stopping medication causes symptoms to return.

What Is the Best Diet to Follow?

There is not much scientific evidence that eating or avoiding particular foods will definitively treat hypothyroidism. It is important, however, to get an optimal amount of iodine in your diet, since too little iodine can itself cause hypothyroidism. Good sources include iodised table salt, saltwater fish, dairy products and eggs.

The single best thing you can do for your thyroid function is to eat a well-balanced, nutrient-rich diet. Our detailed guide to food and thyroid health covers iodine, selenium, zinc, goitrogens, soy and the local iron-rich foods that help with the anaemia and constipation that often accompany an underactive thyroid.

Diet supports treatment. It does not replace thyroxine.

What Happens If Hypothyroidism Is Left Untreated?

Hypothyroidism is a common condition that responds well to thyroid supplementation. But if left untreated, it can lead to a number of health problems.

Goitre. The thyroid gland, under continuous stress to produce hormone, enlarges — leading to an externally visible swelling in the front of the neck.

Cardiovascular consequences. Untreated hypothyroidism leads to unchecked weight gain and obesity, which badly affects cardiovascular function. Patients also face an increased risk of developing atherosclerosis, driven partly by the rise in cholesterol that occurs when thyroid hormone is deficient.

Mental health. Hypothyroidism is often associated with low mood and depression. Left untreated, it may contribute to ongoing mental health difficulties — and because the symptoms overlap so closely with primary depression, thyroid testing is a standard part of assessing unexplained low mood.

Fertility. Hypothyroidism may be a cause of infertility and can contribute to difficulties in conception in women. It also carries risks in pregnancy, which is why thyroid function is checked and monitored closely in pregnant patients.

Myxoedema. In extreme cases, when hypothyroidism is left untreated for a long time, a life-threatening condition called myxoedema may occur. In this condition metabolism slows to such an extreme degree that the patient may fall into a coma. Myxoedema can be life-threatening and fatal, and requires emergency intensive care.

These outcomes are the reason the condition is worth diagnosing early. All of them are avoidable with a daily tablet and periodic blood tests.

Thyroid Care at THANC

Thyroid conditions at THANC are managed through the thyroid and parathyroid surgery service.

Most hypothyroidism is managed medically with thyroxine and does not require surgical input. Specialist referral becomes relevant when there is a compressive goitre affecting breathing or swallowing, a thyroid nodule needing evaluation, or where hypothyroidism follows thyroid surgery or radioactive iodine treatment.

Because THANC is a head and neck hospital, we are particularly well placed to assess the ENT consequences of thyroid disease — the voice changes, swallowing difficulty and airway symptoms that often bring patients in before the underlying thyroid problem has been identified.

Book a consultation if you have symptoms of an underactive thyroid, or a neck swelling that needs assessment.