What Causes Hypothyroidism?

Hypothyroidism, otherwise labeled as an underactive thyroid, is a state wherein the thyroid gland does not put out a sufficient amount of hormones. Hypothyroidism can be the result of Hashimoto thyroiditis, a type of autoimmune condition, exposure to radiation or the removal of the thyroid gland in surgical procedures, or medications that limit the amount of thyroid hormones produced.

Individuals of any age can experience hypothyroidism, however it is more likely for older individuals over the age of 50 years and females than males. Only a limited amount of people have obviously expressed hypothyroidism. The amount of people in the general public that have visible hypothyroidism in the United States ranges from 0.3% to 3.7%. A large number of individuals have a moderate form of insufficient thyroid hormone (subclinical hypothyroidism).

Types of Hypothyroidism in Children

There are several different types of hypothyroidism, including:

Congenital Hypothyroidism

CH is a condition that arises when the thyroid gland is either not present or is not operating in an expected way before birth. This issue is quite common, happening to somewhere between 2,500 and 3,000 newborns. In the USA, each state is required to carry out a CH test as part of their routine check for newborn babies.

Several elements, for example your family history, your infant’s physical examination, the level of hypothyroidism at the time of detection, and the treatment during the initial two to three years of life, will assist your infant’s specialist to find out if the cause is inherited (passed down through your family), and if treatment is needed.

Autoimmune Hypothyroidism: Chronic Lymphocytic Thyroiditis

Chronic lymphocytic thyroiditis (CLT), an autoimmune disorder, is the most common source of acquired hypothyroidism. In this condition, the child’s defensive system combats the thyroid gland, resulting in harm and weakened functioning. This ailment was initially documented by the Japanese doctor Hakaru Hashimoto, consequently it is mostly known as Hashimoto’s thyroiditis.

Girls are more likely to experience CLT than boys, and teenagers more commonly than younger people. Individuals suffering from different autoimmune conditions, primarily type 1 diabetes, are more likely to acquire CLT. Around a quarter to a third of individuals with diabetes develop CLT. Therefore, CLT testing is done on a yearly basis as part of managing diabetes.

Iatrogenic Hypothyroidism

A form of hypothyroidism acquired by children resulting from medical or surgical removal of the thyroid gland is known as iatrogenic hypothyroidism. The consequence of taking out the thyroid gland is that the body cannot produce thyroid hormone, resulting in a condition called iatrogenic hypothyroidism.

Central Hypothyroidism

Central hypothyroidism is a condition in which the brain is unable to generate thyroid-stimulating hormone (TSH), which is the signal that instructs the thyroid gland to produce hormones. Disorders related to an abnormal thyroid gland are far more frequent than this specific condition. In central hypothyroidism, the majority of individuals have an ordinary thyroid gland.

In addition to a low TSH, central hypothyroidism may be associated with deficiencies of other hormones, including:

Growth hormone
Adrenocorticotropic hormone, which stimulates the adrenal gland during stress
Luteinizing and follicle-stimulating hormone, which control ovary and testicular function
Prolactin, which helps females produce milk
Oxytocin, which is important for childbirth and lactation
Antidiuretic hormone, which controls urine production

The cause of central hypothyroidism might be hazardous growth of the hypothalamus or pituitary glands (the region in the brain where TSH is generated), trauma, a tumor, or treatment for said tumor (surgery or radiation, for example). This condition of the thyroid which is located in the center of the body may run in families, and male and female individuals are equally susceptible to it.

Symptoms

Hypothyroidism can cause a wide range of differing symptoms, however they won’t show up immediately and can take quite a while to become noticeable. Signs and symptoms that appear inconsistently and can change frequently over a period of time are generally not related to thyroid hormone irregularities.

Common symptoms of hypothyroidism may include:

Dry, pale skin
Thin, brittle hair and fingernails
Increased sensitivity to cold
Feeling tired
Constipation
Slow thinking
Depression
Muscle and joint pain
Slow heart rate
Heavier menstrual periods
Hoarse voice
Enlarged tongue
Weight gain or difficulty losing weight
Fertility problems

Symptoms in Infants and Children

Almost all babies born in the US are tested for hypothyroidism to stop cognitive growth issues from happening if attention is not given soon enough. The manifestations of hypothyroidism in youngsters rely on when the disorder begins.

A majority of newborns with a disorder leading to inheritable hypothyroidism do not exhibit noticeable signs at first. Occasionally, newborns may exhibit the following symptoms: yellow skin, loud respiration, and a larger than usual tongue.

Signs of hypothyroidism that have gone unnoticed and have not been treated in babies include difficulty feeding, slow growth, stopped up bowels, raspy voice, and drowsiness.

In kids who have not had treatment, later signs include a bulging tummy; scaly, dry skin; and later development of teeth. In more severe instances, yellow lumps that are elevated to the touch (known as xanthomas) might be visible on the skin, created by the collection of cholesterol.

If kids with hypothyroidism don’t get the necessary therapy timely, they might end up being taller than their age range; have a puffiness, bloated look; as well as have learning issues. A child that is not growing at a normal rate should be tested for hypothyroidism.

Causes

There are a variety of long-term or short-term circumstances that can lessen the production of thyroid hormones, leading to hypothyroidism. The majority of cases of hypothyroidism stem from issues originating in the thyroid gland. In such cases, the disorder is called primary hypothyroidism. Disorders of the pituitary gland are the cause of secondary hypothyroidism, whereas disorders of the hypothalamus are the cause of tertiary hypothyroidism.

The two most common causes of primary hypothyroidism are:

Hashimoto thyroiditis. This is an autoimmune condition (chronic lymphocytic thyroiditis) in which the body’s immune system attacks its own thyroid cells.
Overtreatment of hyperthyroidism (an overactive thyroid).

Complications

Hypothyroidism increases the risk for physical and mental problems.

Emergency Conditions

Myxedema Coma

A rare, life-threatening complication of untreated hypothyroidism. Symptoms include:

Constipation
Delirium
Fluid buildup
Reduced lung function
Seizures

Myxedema coma is rare; however, it can happen in people who are enduring intense stress, for example, people with a sickness or strong cold, or after a medical procedure. There is a potential danger associated with utilizing certain medications, including sedatives, painkillers, narcotics, amiodarone, and lithium. Emergency treatment is required.

Suppurative Thyroiditis

A life-threatening infection of the thyroid gland. It is highly uncommon for the thyroid to become infected, as it typically has a strong resistance to infection. Individuals who were previously diagnosed with a thyroid disorder, such as Hashimoto thyroiditis, might be more vulnerable to suppurative thyroiditis than the typical population. It often begins with an upper respiratory infection. Symptoms include:

Difficulty swallowing and speaking
Fever
Neck pain
Rash
Immediate treatment is required.

Heart Problems

Triiodothyronine (T3) is a type of thyroid hormone that influences both the heart directly and obliquely. The two are firmly connected to pulse and the amount of blood that the heart pumps. T3 has the effect of calming the muscles of the arteries, thus providing advantages. This promotes a steady circulation of blood through the arteries and veins.

Hypothyroidism is associated with:

Unhealthy cholesterol levels. Hypothyroidism raises levels of total cholesterol, LDL (bad) cholesterol, triglycerides, and other lipids associated with heart disease. Treating the thyroid condition with thyroid replacement therapy can significantly reduce these levels.
High blood pressure. Hypothyroidism can slow the heart rate, reduce the heart’s pumping capacity, and increase the stiffness of blood vessel walls. These effects can lead to high blood pressure. Everyone with chronic hypothyroidism, especially pregnant women, should have their blood pressure checked regularly.
Heart failure. Hypothyroidism can affect the heart muscle’s contraction and increase the risk of heart failure in people with heart disease.
Pericardial effusion. Hypothyroidism sometimes leads to the buildup of fluid in the sac that surrounds the heart, known as a pericardial effusion.
The evidence for effects of subclinical hypothyroidism on heart disease is mixed. Some studies, but not all, indicate that subclinical hypothyroidism increases the risks for coronary artery disease, heart failure, and even stroke. However, many researchers believe that treatment of subclinical hypothyroidism will not help prevent or improve these problems.

Mental Health Effects

Common in hypothyroidism and can be severe. Hypothyroidism should be taken into account when attributing any long-term sadness, especially for older female individuals.

If left without proper treatment, hypothyroidism can have long lasting negative impacts on mental health and behaviour, and can even lead to dementia over time. It is not clear if therapy can completely turn around memory and attention issues, though studies point out that solely the intellectual disability which happens at birth in hypothyroidism is permanent.

Hypothyroidism and Obesity

Severe thyroid deficiency can result in a slowed rate of metabolic activity leading to a decrease in the consumption of calories. Nevertheless, weight gain or obesity are almost never related to hypothyroidism.

Despite current conditions, medical personnel commonly request thyroid assessments when conducting general examinations in obese patients. This is a reasonable practice. Along with it, thyroid activity tests should be done simultaneously with exams for enlarged cholesterol because hypothyroidism is related to raised LDL quantities (“bad” cholesterol) owing to a diminished metabolism of LDL.

Having an above average body mass index (BMI) is linked with slightly increased levels of thyroid-stimulating hormone (TSH), although this is not indicative of thyroid disease but rather a consequence of being overweight. Put differently, it is more typical for an individual to experience a slight raise in TSH due to being overweight instead of a mild rise in TSH causing a major gain in weight.

Your child’s doctor should evaluate their linear growth (height gain) to see if the extra weight is accompanied by regular or greater height, not a decrease in linear growth, which is often associated with hypothyroidism, in order to verify the link between being overweight and a slight rise in TSH.

The pediatrician of your kid may also direct laboratory screens for Hashimoto’s thyroiditis or high LDL and overall cholesterol levels to find out if the hypothyroidism should be treated.

Hypothyroidism and Pregnancy

During the first trimester of gestation, the unborn baby relies on the mother for thyroid hormones. The thyroid hormone has an indispensable role in the proper growth of the brain. Maternal hypothyroidism can cause irreversible harm to the fetus. Early investigations demonstrated that kids brought into the world to moms with hypothyroidism while pregnant had a lower intellect and hindered psychomotor advancement. If the levels of thyroid hormone are regulated properly, women with hypothyroidism are able to give birth to healthy babies that are not affected by the condition.

The advice right now is to find out if any female patients who have recently come in for a prenatal visit have had prior experience with thyroid-related issues or have taken thyroid hormone medicine. It is suggested that women who are at a heightened chance of having hypothyroidism have their thyroid functions and/or antibodies tested in a laboratory. Identifying and addressing maternal hypothyroidism in the early stages of pregnancy might stop any potentially damaging effects to the baby. Women who take thyroid hormone before becoming pregnant must have their thyroid functioning tested often during the pregnancy, since it is most likely that the hormone dosage needs to be raised. Women should seek more details and explanations from their usual healthcare providers regarding this important subject.

Testing and Diagnosis

A comprehensive medical history and physical exam of your child are the first steps of a diagnostic assessment. The most widespread source of congenital hypothyroidism is when the thyroid gland does not move to its appropriate location in the neck in the early stages of fetal growth.

Clinical experts use a variety of diagnostic tests to diagnose hypothyroidism, including:

Thyroid function screening, a blood test that measures thyroid hormone (thyroxine or T4) and serum TSH (thyroid-stimulating hormone) levels. Hypothyroidism is diagnosed when the TSH levels are above normal and T4 levels are below normal. A less severe or earlier form of hypothyroidism is reflected by an elevated TSH and a low-normal T4, a condition called “compensated” or “subclinical” hypothyroidism.
Anti-thyroid antibody level studies. Anti-thyroperoxidase (anti-TPO) and anti-thyroglobulin (TgAb) are elevated in autoimmune hypothyroidism. In contrast to the antibody found in Graves’ disease (a type of hyperthyroidism), these have no function. They only serve as an indicator of the diagnosis.
Thyroid ultrasound, which uses ultrasonic waves to image your child’s thyroid and lymph nodes. An ultrasound does not expose your child to radiation. In some forms of hypothyroidism, the thyroid tissue will have an irregular appearance and there may be areas that look like a thyroid nodule. Expert review of the images by an experienced pediatric endocrinologist will determine if the area warrants further investigation with fine needle aspiration (FNA) or if it can be followed with repeat thyroid ultrasound to determine if FNA is needed. Ultrasound can also be used to ensure a newborn with congenital hypothyroidism has a normal thyroid in the correct location.
Nuclear medicine uptake and scan, which helps determine how well your child’s thyroid tissue absorbs iodine, a key ingredient in making thyroid hormone. For the test, your child is give a very small amount of radioactive iodine — usually technetium 99m (TC-99m) or I-123 — then we measure how much iodine is absorbed (uptake) and the pattern of distribution of the radioiodine in the thyroid tissue (scan). This test can also be used to determine the location of thyroid tissue for newborns with congenital hypothyroidism.

Treatment for Hypothyroidism

In the majority of occurrences, hypothyroidism can be remedied by taking thyroid hormone replacement medication (levothyroxine). Levothyroxine is equivalent to the thyroxine (T4) that is normally present in our bodies. If used in the prescribed manner, it will help bring a child’s hormone levels of the thyroid back to normal. This medication can be administered to people of all ages, ranging from infants to grown-ups.

It is not regular, but it may be helpful for patients to take both levothyroxine (T4) and liothyronine (T3). We will investigate and discuss this option with you based upon your kid’s answer to T4-exclusive treatment, plus the follow-up thyroid hormone lab values.

If your infant is diagnosed with hypothyroidism and treatment is recommended, you can pulverize the pill and provide it to your baby via breastmilk, formula, or water.

Older children can swallow or chew the medicine. Eating something can hinder the intake of the pill, however, it is far more significant to build a habit of consuming it every day at roughly the same time (either morning or evening) rather than worrying too much about whether to have it on an empty stomach or not.

It is advisable not to administer thyroid replacement medication to your kid in conjunction with taking iron or calcium.