Thyroid Problems and Fatigue

The thyroid in brief

The thyroid is a small gland in the neck that makes hormones affecting things like heart rate and body temperature. [1] Both too little thyroid hormone (underactive, or hypothyroidism) and too much (overactive, or hyperthyroidism) can be involved in tiredness. This page is educational; thyroid problems are diagnosed by blood tests, not by symptoms.

Underactive thyroid

NHS lists feeling extremely tired as one of the common symptoms, along with feeling cold, putting on weight, constipation, difficulty concentrating, low mood, dry skin and hair, a hoarse voice, and irregular or heavy periods. Symptoms may be mild, usually develop slowly, and are common in other conditions too. [2]

• How it is checked: a GP may ask about symptoms and family history, may examine the neck, and may order blood tests for thyroid-stimulating hormone (TSH) and thyroxine (T4). [2]
• Common cause: in the UK the main cause is an autoimmune condition called Hashimoto's disease. [2]
• Established care: it is usually treated with levothyroxine tablets, usually for life, with regular blood tests to check the dose. The wrong dose can cause side effects, including problems sleeping. [2]
• If untreated: risks include heart problems and bone problems, and in very rare cases a life-threatening condition called myxoedema coma, which is an emergency. [2]

Overactive thyroid

NHS lists nervousness, anxiety, irritability, mood swings, difficulty sleeping, persistent tiredness and weakness, heat sensitivity, a fast or irregular heartbeat, trembling and weight loss as possible symptoms. [1] Tiredness can therefore appear with either too little or too much thyroid hormone. The NHS tiredness page also lists restlessness, nervousness and muscle weakness with an overactive thyroid. [3]

Mild thyroid changes and tiredness

"Subclinical hypothyroidism" means TSH is raised while thyroxine is still normal. A secondary analysis of the TRUST randomized trial followed 638 adults aged 65 or older with persistent subclinical hypothyroidism. Among those with greater symptom burden at the start, levothyroxine did not improve hypothyroid symptoms or tiredness over one year compared with placebo. Evidence: one randomized-trial analysis, in older adults only. [4] This does not mean thyroid medicine fails in true hypothyroidism, which is a different situation. [2] Treatment decisions belong with your clinician. Do not stop or change thyroid medicine on your own.

Self-treating a "thyroid" problem

Tiredness with a normal thyroid test is not a reason to buy thyroid or "adrenal" supplements. For claims about "adrenal fatigue", see Cortisol, adrenal fatigue and what the science supports. The thyroid is just one of many contexts for fatigue; see Why am I so tired?.

Pregnancy and thyroid

If you have an underactive thyroid and are pregnant or planning pregnancy, NHS says to tell your GP, because more tests are needed and your levothyroxine dose is likely to change. [2]

When to get help

See a GP if you think you might have an underactive thyroid. [2] Also see one if you have an overactive-thyroid pattern such as a fast or irregular heartbeat, tremor and weight loss. [1] See Fatigue: when to get help. Before adding supplements while on thyroid medicine, read How interactions work.