what are signs & symptoms of hyperthyroidism ?What is normal function of thyroid hormones? What is it’s effect on metabolism?what are risk factors for hyperthyroidism?
We will answer all this questions and more in this article.
Physiological Effects of Thyroid Hormones
- The thyroid gland secretes two biologically active hormones thyroxine (T4) and triiodothyronine (T3).
- The variuos functions of thyroid hormone in the body are:
Effects on body Metabolism:
- Thyroid hormones affects almost all the cells in the body.
- Thyroid hormone will cause increase in the basal metabolic rate of the cells.
- Which means that the amount of energy that is used up by the body to sustain life function without any physical activity.
- There is increase in oxygen consumption and increased breakdown of ATP for energy.
- When there is increase in metabolism along with this there also occurs increased heat production by the body.
1. ROLE OF THYROID HORMONE IN CARBOHYDRATE METABOLISM
- Increases gluconeogenesis (synthesis of glucose).
- Increases glycogenolysis (breakdown of glycogen to form glucose).
- Increases the insulin dependent glucose entry inside the cells
2. ROLE OF THYROID HORMONE IN FAT METABOLISM
- Thyroid hormone causes the fat to move from adipose tissues into the blood stream, this is called as fat mobilization.
- It causes increased fatty acid degradation and de novo fatty acid synthesis in liver.
- Thyroid hormone also plays a role in fatty acid oxidation.
- One more most important effect it has on cholesterol is that the serum cholesterol rises when there is decrease in thyroid hormone like in hypothyroidism.
- This is also called as reverse cholesterol transport.
- Increases lipoprotein lipase activity.
3. THYROID ALSO HAS A ROLE IN METABOLISM OF VITAMINS IN OUR BODY
4. ROLE OF THYROID HORMONE IN GROWTH AND DEVELOPMENT
- Thyroid is necessary for normal growth and development of children.
- If there is deficiency in thyroid hormone it may result in growth retardation and may also result in mental retardation in children.
EFFECT OF THYROID HORMONE ON VARIOUS ORGAN SYSTEMS
1. Cardiovascular system:
- Increases heart rate (positive inotropic effect ).
- Increase cardiac output.
- Increases contractility of heart (positive chronotropic effect).
- Causes peripheral vasodilatation.
2. Central nervous system:
- Thyroid hormone are said to have an important role in development of nervous system (neural growth and differentiation) in the fetal life and also maintainance of the normal brain function.
- Thyroid hormone is thought to play a role in differentiation of brain cells and myelination of nerves.
3. Skeletal system:
- Thyroid hormone is required for growth of long bones.
- It regulates the process of bone formation and bone resorption
4. Reproductive system:
- Thyroid hormone regulates the growth, differentiation and metabolism of various organs in the body including the ovaries, uterine tubes, placenta .
- It is not clearly known but thyroid hormone may have some role in spermatogenesis.
What are the signs and symptoms of hyperthyroidism?
When there is increase in the thyroid hormone in the body the effect of the thyroid hormone on the body increases .
Therefore the signs and symptoms of hyperthyroidism are nothing but exaggeration of all the functions of the thyroid hormone on the body.
The main function of thyroid hormone is it increases basal metabolic rate.
In hyperthyroidism there is increased amount of thyroid hormone production which causes increase in the metabolism this is called as hypermetabolic state.
Most prominent symptoms which are seen in hyperthyroidism are due to its hypermetabolic state.
Symptoms of hyperthyroidism include:
General signs and symptoms of hyperthyroidism are:
- Fatigue And weakness: this occurs because there is increased metabolic rate so the ATP which is required for energy is all used up resulting in patient feeling tired and weak.
- Losing weight suddenly, without trying: people with hyperthyroid loose weight even with an increased appetite. This occurs because the excess amount of thyroid in the blood causes the breakdown of the calories from the food as well as causes rise in the metabolic rate of the body.
- Sensitivity to heat.
- Difficulty sleeping.
- shortness of breath with exertion.
- Swelling in the neck. This occur when there is enlargement of the hyperactive thyroid gland.
This swelling in the neck is called goiter. It could be a single lobe that may enlarge or the whole lobe may enlarge.
Sometimes the enlarged gland may have a nodular surface in this case it is called as multinodular goiter.
Sometimes a solitary nodule may be seen o palpable in the thyroid gland.
Pressure effects due enlarged thyroid gland are:
- Pressure on esophagus causes difficulty in swallowing
- pressure over the trachea or larynx causes stridor (noisy breathing) and later on can cause difficulty in breathing (dyspnoea).
- pressure over the recurrent laryngeal nerve causes hoarseness of voice.
Signs and symptoms of hyperthyroidism on Skin and adnexa
- hot and moist skin
- Thinning and/or smooth velvety skin: this is because the adipose tissue or the subcutaneous fat gets metabolized by the increased metabolic rate of the body.
- Thyroid acropachy (clubbing of fingers).
- Hair loss.
- Plummer nails
- Fine, brittle hair
Signs and symptoms of hyperthyroidism on Gastrointestinal symptoms
- Nausea and vomiting.
- Increased appetite: this is because there is increased basal metabolic rate where in the body utilises the glucose requires more and more energy so the person feels hunger frequently.
- Increased bowel movements or diarrhea: thyroid hormones increases the gastric motility and therefore reduces the time the food stays in the intestines.
Signs and symptoms of hyperthyroidism on Cardiovascular symptoms
- Fast or uneven irregular heartbeat or palpitations.
- Can even cause atrial fibrillation. Atrial fibrillation can lead to strokes, and also congestive heart failure.
- Soft systolic murmur which occurs due to increased pulse pressure.
- Angina, cardiomyopathy.
- High output cardiac failure, in some patients diastolic dysfunction can occur resulting in high output cardiac failure also known as thyrotoxic dilated cardiomyopathy.
Central nervous system
- anxiety, crankiness.
- Mood swings, emotional liability.
- Inability to concentrate.
- Shaking in your hands and fingers (tremors).
- Restlessness, agitation,
- Hypokalemic periodic paralysis
Signs and symptoms of hyperthyroidism on Visual changes
- Sensitivity to light (photophobia).
- Irritation of eye and excessive tears. this can lead to corneal ulceration.
- Double vision or diplopia: due to involvement of lateral rectus muscle of the eye.
- Forward protrusion of eyeball called as exophthalmos. This occurs due to deposition of GAG (glycose amino glycans ) behind the eye ball.
- Chemosis (redness of eye).
Signs and symptoms of hyperthyroidism which are seen in the eye
Dalrymple sign – retraction of upper eyelid which makes the upper sclera visible.
Von Graefe sign – upper eyelid lags behind the eyeball when patient looks down.
Kocher sign – wide stare.
Stellwag sign – decreased blinking .
Moebius sign – inability of convergence of eyeball.
Joffroys sign – lack of wrinkling on the forehead while looking up.
- Muscles weakness.
- Proximal myopathy.
- Osteoporosis due to decreased calcium levels (hypocalcemia).
Signs and symptoms of hyperthyroidism on Reproductive system
- Changes in menstrual cycle that is,they have irregular and scant periods.
- Spontaneous abortions.
- Male impotence.
- Loss of libido.
other Signs and symptoms of hyperthyroidism
- Breast development in men.
Risk factors for hyperthyroidism
- Age: it is more common in older individual aged more than 60 years of age.
- Though it can happen at any age group.
- Gender: females are more frequently affected than males.
- Some medical conditions/or certain type of viral infection can cause increase in thyroid.
- If had a history of any autoimmune condition.
- Personal or family history of thyroid disorders
- Pregnant female may develop thyroiditis after delivery of the baby.
- Patient taking iodine supplements
- Japanese people
- People who eat diet containing saltwater fish ( these fish are rich source of iodine).
- Patients on amiodarone or iodine containing drugs
- Trauma to thyroid gland
- Excessive stress for a long time
- Vitamin D deficiency, selenium deficiency