ConditionHormones & metabolism
Thyroid Disorders
Thyroid disorders are conditions that affect the thyroid, the butterfly-shaped gland in the front of the neck that controls metabolism. The most common are hypothyroidism (underactive thyroid, usually from Hashimoto's disease), causing tiredness, weight gain and feeling cold, and hyperthyroidism (overactive thyroid, usually from Graves' disease), causing weight loss, a racing heart and anxiety. Others include goiter, thyroid nodules, thyroiditis and thyroid cancer. They are common, especially in women, and a simple TSH blood test detects most of them.
Also called: Thyroid disease, thyroid dysfunction, thyroid problems
At a glance
- What they are
- Conditions affecting thyroid hormone levels or thyroid structure.
- Most common
- Hypothyroidism (often Hashimoto's) and hyperthyroidism (often Graves' disease).
- Structural problems
- Goiter, nodules (very common, mostly benign), thyroid cancer.
- Who is at risk
- Women (5 to 8 times more often than men), people over 60, after pregnancy, family history, autoimmune disease.
- Diagnosis
- TSH and free T4 blood tests; antibodies; ultrasound and biopsy for nodules.
- Treatment
- Levothyroxine for underactivity; antithyroid drugs, radioactive iodine or surgery for overactivity; surgery for cancer.
When to get help
Call 911 or go to the ER
- Fever, very fast or irregular heartbeat, agitation, confusion, vomiting or diarrhea in someone with an overactive thyroid (possible thyroid storm)
- Extreme drowsiness, confusion, low body temperature and slow breathing in someone with an underactive thyroid (possible myxedema coma)
- A rapidly growing neck swelling with difficulty breathing or swallowing
See a doctor within a day or two
- A racing or irregular heartbeat with weight loss, tremor and heat intolerance
- Bulging, red, painful eyes or double vision with thyroid symptoms
- A painful, tender thyroid with fever after a viral illness
- A neck lump with hoarseness or swollen lymph nodes
Book a routine appointment
- Tiredness, weight gain, constipation, dry skin and feeling cold for weeks
- A lump or swelling at the front of the neck
- Irregular periods, trouble getting pregnant, or mood changes in the year after giving birth
- Taking thyroid medicine and planning pregnancy (doses usually need adjusting)
What the thyroid does
The thyroid makes two hormones, T4 (thyroxine) and T3 (triiodothyronine), using iodine from the diet. These hormones set the pace of metabolism, affecting heart rate, body temperature, energy, weight, digestion, mood, menstrual cycles and growth. The pituitary gland in the brain controls the thyroid with thyroid-stimulating hormone (TSH): when thyroid hormone is low, TSH rises; when it is high, TSH falls.
Hypothyroidism vs hyperthyroidism
| Hypothyroidism (underactive) | Hyperthyroidism (overactive) | |
|---|---|---|
| Common cause | Hashimoto's thyroiditis | Graves' disease |
| Energy | Tired, sluggish | Restless, tired but wired |
| Weight | Gain | Loss, despite increased appetite |
| Temperature | Feel cold | Feel hot, sweaty |
| Heart | Slow | Fast, palpitations, atrial fibrillation |
| Bowels | Constipation | Frequent stools |
| Skin and hair | Dry skin, thinning hair | Warm, moist skin, fine hair |
| Mood | Low mood, slowed thinking | Anxiety, irritability |
| Periods | Heavy | Light or infrequent |
| TSH | High | Low |
Other thyroid disorders
- Goiter: an enlarged thyroid, from iodine deficiency, Hashimoto's, Graves' or multiple nodules.
- Thyroid nodules: lumps in the thyroid, found in up to half of adults on ultrasound; about 9 in 10 are benign.
- Thyroiditis: inflammation of the thyroid. Subacute thyroiditis causes a painful thyroid after a viral illness; postpartum thyroiditis occurs in the year after pregnancy, often with a brief overactive phase followed by underactivity.
- Thyroid cancer: usually presents as a nodule; most types (papillary and follicular) have excellent outcomes.
- Thyroid eye disease: bulging, irritated eyes linked to Graves' disease.
Risk factors
- female sex
- age over 60
- family history of thyroid disease
- other autoimmune conditions such as type 1 diabetes, celiac disease, vitiligo or rheumatoid arthritis
- pregnancy and the first year after birth
- previous thyroid surgery, radioactive iodine or neck radiation
- medicines such as amiodarone, lithium and immune checkpoint inhibitors
- too little or too much iodine
Diagnosis
- TSH: the best first test for most thyroid function problems
- free T4 (and sometimes T3) to confirm and grade the problem
- antibodies: TPO antibodies for Hashimoto's; TSH receptor antibodies for Graves'
- thyroid ultrasound for goiter and nodules
- fine-needle aspiration biopsy for suspicious nodules
- radioactive iodine uptake scan to identify the cause of hyperthyroidism
Biotin (vitamin B7) supplements can distort some thyroid test results; stop them for a few days before testing if advised.
Treatment
- Hypothyroidism: daily levothyroxine, a synthetic T4, adjusted using TSH tests
- Hyperthyroidism: - antithyroid medicines (methimazole; propylthiouracil in early pregnancy) - beta blockers to control heart rate and tremor - radioactive iodine to shrink overactive thyroid tissue - thyroidectomy (surgery)
- Nodules: monitoring with ultrasound for most; surgery or other procedures for suspicious, cancerous or large nodules
- Thyroid cancer: surgery, sometimes radioactive iodine, and long-term monitoring
- Thyroiditis: often temporary; symptom treatment with beta blockers or anti-inflammatories, and levothyroxine if underactivity persists
Thyroid problems and pregnancy
Both underactive and overactive thyroid during pregnancy can affect the baby's development and pregnancy outcomes. People taking levothyroxine usually need a dose increase as soon as pregnancy is confirmed. Thyroid function should be checked when planning pregnancy if you have thyroid disease.
Frequently asked questions
What are the most common thyroid disorders?
The most common are hypothyroidism (underactive thyroid), often from Hashimoto's thyroiditis, and hyperthyroidism (overactive thyroid), often from Graves' disease. Thyroid nodules and goiter are also very common.
What are the early signs of thyroid problems?
An underactive thyroid causes tiredness, weight gain, feeling cold, constipation and dry skin. An overactive thyroid causes weight loss, a racing heart, anxiety, heat intolerance and tremor. A swelling in the neck can also be an early sign.
What blood test checks the thyroid?
The TSH (thyroid-stimulating hormone) test is the main screening test. A high TSH suggests an underactive thyroid, and a low TSH suggests an overactive one. Free T4 and antibody tests help confirm the cause.
Why are thyroid problems more common in women?
Autoimmune thyroid diseases such as Hashimoto's and Graves' are much more common in women, likely due to hormonal and immune differences. Pregnancy and the postpartum period also trigger thyroid problems in some women.
Can thyroid disorders be cured?
Some can. Graves' disease may go into remission, and thyroiditis is often temporary. Hypothyroidism is usually lifelong but easily controlled with daily medicine. Most thyroid cancers are curable with treatment.
Sources
This guide was written from current patient and clinical guidance, including:
- American Thyroid Association: Thyroid Information for Patients
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): Thyroid Tests; Hypothyroidism; Hyperthyroidism
- American Thyroid Association: 2016 Guidelines for Diagnosis and Management of Hyperthyroidism
- American Thyroid Association: 2015 Guidelines for Thyroid Nodules and Differentiated Thyroid Cancer
- MedlinePlus: Thyroid Diseases