Hyperthyroidism: Symptoms, Causes, Diagnosis, and Treatment
Apr 27, 2023
Hyperthyroidism is a condition in which there is an increased function of the thyroid gland. It is also known as overactive thyroid, because of excessive releases of thyroid hormone. This condition can speed up the metabolism of the body. The main hormones which are released by the thyroid gland include triiodothyronine (T3) and thyroxine (T4). Symptoms, such as weight loss, hand tremors, and rapid or irregular heartbeat (palpitations) can be seen in patients suffering from hyperthyroidism.
There can be primary or secondary causes of hyperthyroidism. Primary causes are the causes which are directly related to overworking of thyroid gland i.e. excessive production of the hormones by thyroid gland whereas secondary causes are related to pituitary abnormalities.
Most common cause of Primary Hyperthyroidism - Grave’s disease.
Cause of Secondary Hyperthyroidism-Due to Pituitary adenoma
Toxic multinodular Goitre/toxic adenoma/activating mutation of TSH receptor
Gestational Trophoblastic Neoplasia (HCG and TSH are similar in structure, thus HCG can bind to TSH receptor and stimulate them)
In Grave’s disease the antibodies are formed against the body knowns as Lats (Long Acting Thyroid Stimulating Antibodies) also known as TSI (Thyroid Stimulating Antibody) or TBII (Thyrotropin Binding Inhibiting Immunoglobulin Assay). These antibodies behave like TSH and they stimulate the gland to release more hormones leading to over exertion of the thyroid gland.
Pituitary adenoma is the tumor of the adrenal gland. It can be micronodular or macronodular. It causes excessive release of TSH thus resulting in excessive production of T3 and T4.
Toxic Multinodular Goitre
Toxic multinodular goitre also known as toxic adenoma. There is mutation of TSH receptors releading to overproduction of thyroid hormones.
Jod Basedow Effect
Due to excessive consumption of iodine on a dietary basis there is an increase in trapping of iodine in the body which leads to an increase in T4 levels in the body. There is no dysfunction of the gland in this effect; it is just due to dietary consumption of iodine for many years.
It is most likely in the countries where there is excessive consumption of beef and cattle. In case if the the thyroid gland of the animal is diseased and is accidently consumed by the person it causes exogenous response in the body of the person who consumed it leading to increase in production of hormones in the body.
Struma ovarii is the tumor of the ovarian gland. It causes stimulation of release of thyroid hormones resulting in excessive levels of the thyroid hormones in the body.
Gestational Trophoblastic Neoplasia
Gestational Trophoblastic Neoplasia is a condition in which tumors develop during the early phase of Pregnancy leading to excessive release of beta HCG levels in the body. The beta HCG levels mimic the structure of TSH thus when the levels of beta HCG are increased they bind to TSH receptors thus leading to excessive release in level of thyroid hormones.
What are the risk factors of hyperthyroidism?
Following are the risk factors for hyperthyroidism
Family history of thyroid disease.
Certain chronic illnesses that include pernicious anemia & primary adrenal insufficiency.
Pregnancy raises the risk of thyroiditis which can lead to hyperthyroidism.
What are the symptoms of Hyperthyroidism?
There are various symptoms of hyperthyroidism that can impact the entire body. You can experience certain symptoms whereas some may not be experienced. Symptoms of hyperthyroidism include:
Hyperactivity and irritability
Palpitations- due to beta 1 receptor stimulation
Fine tremors - due to beta 2 receptor stimulation
BMR increased → Resulting in weight loss
Calorigenesis increased → Causes heat intolerance
Examination of Hyperthyroidism
Sleeping Pulse Rate increased → Most reliable sign to diagnose thyrotoxicosis (resting tachycardia)
Arrhythmias: Atrial fibrillation
CVS → Loud S1, Ejection systolic murmur, Means Lerman Scratch [due to hyperdynamic circulation]
Pretibial Myxoedema, orange discoloration on shin initially
Myxoedema is non pitting in nature
Lid retraction is present due to contraction of Muller’s muscle [ due to sympathetic overactivity]
Lid-lag sign/ star sign
Inability of upper eyelid to follow the object from top to bottom
“Inferior Rectus" is most common extra ocular muscle involved
Due to pressure on optic nerve
Manifestations of grave’s ophthalmopathy
0 = No signs or symptoms
1 = lid retraction or lag present but no symptoms
2 = Soft tissue involvement (periorbital edema)
3 = Proptosis (>22 mm)
4 = Extraocular muscle involvement (diplopia)
5 = Corneal involvement
6 = Sight loss
Smoker with grave’s ophthalmopathy
Treatment with radioiodine cause thyroid storm
Endocrinological cause of Clubbing/Acropachy: Grave’s disease.
This sign is used to detect obstruction in patients with goitre
On Raising arms, there will be Facial congestion due to compression of Superior Vena Cava by retrosternal goiter.
It tells about the retrosternal extension of goiter.
What is the Diagnosis of Hyperthyroidism?
Hyperthyroidism can be diagnosed with a medical history of the person, physical exam and certain blood tests.
Blood test: Blood tests measure the levels of hormones i.e T4 and T-3 and thyroid-stimulating hormone (TSH) that can help to confirm a diagnosis of hyperthyroidism. A high level of T-4 and a low level of TSH can be commonly found in people suffering from hyperthyroidism’.
Thyroid ultrasound: It uses high-frequency sound waves which make images of the thyroid gland. Ultrasound is better in finding nodules of the thyroid gland. There's no exposure to radiation to patients in this test, so it can be used on pregnant or breastfeeding females or other patients who can't take the radioiodine test.
What is the treatment of Hyperthyroidism?
There are various types of treatments which are available for hyperthyroidism. The underlying cause of hyperthyroidism and how severe it is can help us to decide the treatment as well. Based on your condition your healthcare worker can help you to provide the best treatment option. Treatment may include:
Anti-thyroid medicine: These medications help in resolving the symptoms of hyperthyroidism as they prevent the thyroid gland from producing excessive amounts of hormones. Anti-thyroid medications include PTU (Propylthiouracil) . This drug is safe in pregnancy i.e. in the first trimester and in breastfeeding as it has high protein binding. Carbimazole and Methimazole are Safe in the 2nd Trimester. It is also Drug of choice. Anti-thyroid medicine treatment lasts from 12 to 18 months approximately. After this certain period of time the dose can be decreased slowly or it can also be stopped if symptoms disappear and blood test analysis indicates that thyroid hormone levels have now come into the standard range. In some people, anti-thyroid medicine can help in causing hyperthyroidism into long-term remission but in some people hyperthyroidism can come back even after treatment.
Beta blockers: These medicines help in reducing symptoms of hyperthyroidism, such as tremors and rapid heart rate (tachycardia) and heart palpitations. Sometimes these drugs are provided by health care to reduce the symptoms until thyroid hormones come back into normal levels. Side effects of these include fatigue and certain sexual problems.
Radioiodine therapy: The thyroid gland takes up radioiodine and thus causes the thyroid gland to reduce in size. Radioiodine is taken orally i.e. through mouth. symptoms typically reduce within several months by this method. This method helps in causing thyroid gland activity to slow down and thus makes the thyroid gland underactive and this condition is known as hypothyroidism.
Thyroidectomy: In this surgery we try to remove some part or the whole thyroid gland. This method is not preferred to treat patients of hyperthyroidism but it can be an option for pregnant patients as antithyroid drugs are not preferred through the whole pregnancy period. There are certain risks of this surgery as it can cause damage to the vocal cords and parathyroid glands. The parathyroid glands are present on the back of the thyroid gland and these glands help to control the level of calcium in the blood
What are the complications of hyperthyroidism?
It is the complication of Graves’ disease which is one of the causes of hyperthyroidism. It is also known as Graves’ eye. Certain complications of Graves’ eye disease are:
Bulging of eyes.
Loss of vision
Diplopia (Double vision).
Sensitivity to light.
What happens if hyperthyroidism is left untreated?
As hyperthyroidism can impact different parts of our body so many different systems can be affected due to increased level of hormones including vascular system (heart) to your skeletal system (bones)
Complications of untreated hyperthyroidism include:
Congestive heart failure
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