Subclinical Hypothyroidism Symptoms, Causes, and Treatment 2023

 

What is Subclinical Hypothroidism?

Subclinical hypothyroidism is a mild and premature form of hypothyroidism, in which TSH (Thyroid-stimulating hormones) detects with elevated and normal T3 and T4 values.

Hypothyroidism is a medical condition that happens when the human body doesn’t produce enough thyroid hormone. Subclinical hypothyroidism has the potential to develop hypothyroidism called overt hypothyroidism in contrast.

Studies showed that women are more likely to develop subclinical hypothyroidism condition.

Diagnosis requires laboratory tests, especially TPT (Thyroid Profile Test).

Treatment is scheduled according to the patient’s condition which the health provider decides but generally, synthetic thyroid hormones are given orally.

Generally, Women are more likely to develop subclinical hypothyroidism condition.

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Subclinical Hypothyroidism and Hypothyroidism
 

Biochemically subclinical Hypothyroidism is defined as, a normal free serum thyroxin (T4), with an elevated serum TSH (Thyroid stimulation hormone), concentration.

It’s called subclinical hypothyroidism due to the serum level of TSH, released from the front of the pituitary gland being elevated. Whereas, the thyroid hormones released from the thyroid gland are still contained within the laboratory’s normal range.

Thyroid hormones assist support metabolic functions, the brain, and the heart. When these hormones are not working properly, this affects normal body functions.

According to the studies, subclinical hypothyroidism can progress to full-blown hypothyroidism within six years of initial diagnosis.

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Causes of Subclinical Hypothyroidism and Hypothyroidism

Underside the brain a gland present called the pituitary gland releases several hormones, comprising, a chemical called thyroid-stimulating hormones (TSH). This TSH activates the thyroid (a butterfly-shaped gland located at the front of the neck), to produce T3 (20%), and T4 (80%) hormones. In subclinical hypothyroidism conditions, TSH increased slightly but T3 and T4 are normal.

Both full-blown hypothyroidism and hypothyroidism share the same causes, comprising;

Subclinical hypothyroidism and full-blown hypothyroidism share the same causes. These include:

• Surgery of the thyroid gland, for example, due to some abnormal thyroid tissue, removal during the neck and head surgery.
• Having medicines contains Iodine or lithium.
• A family history of autoimmune disease, of the thyroid such as Hashimoto’s thyroiditis, this disease harms the thyroid cells due to an autoimmune condition.
• Due to Radioactive Iodine therapy (a treatment for hyperthyroidism), in this condition thyroid hormones releases too much within the Laboratory’s normal values.

Subclinical Hypothyroidism Symptoms

When TSH is only mildly increased, subclinical hypothyroidism most of the time has no symptoms. When symptoms do arise, conversely, they are inclined to be general and unclear and comprise

• Fatigue
• Constipation
• Depression
• Hair loss
• Dryness of skin and hairs
• Unexplained weight gain
• Intolerance to cold
• Hypertension (high blood pressure)
• Frequent and heavy menstrual bleeding in women
• Goiter (enlarged thyroid hormone)

These symptoms can be present in human beings with normal thyroid function and are not related to subclinical hypothyroidism specifically.

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Diagnosis

Diagnosis of subclinical hypothyroidism entirely depends on thyroid function blood test.

Normal range of TSH for non-pregnant adults

The normal range of thyroid stimulating hormones (TSH) for nor-pregnant adults is 0.4-4.5 milli international units per liter of blood (mIU/L).

Normal range of TSH for pregnant women

For pregnant women, the normal range of TSH varies by trimester.

If the thyroid function test indicates a TSH value from 5 to 10 mIU/L and thyroxin (T3 and T4) normal, it means the person has a subclinical hypothyroidism condition.

Grade 1 and Grade 2 Subclinical hypothyroidism

Subclinical hypothyroidism can be classified as grade 1 and grade 2, subclinical hypothyroidism.

When blood tests show 4.5-9.9 mIU/L TSH values it’s called grade 1 subclinical hypothyroidism, whereas when TSH values show the range of 10 mIU/L or more, it is an indication of grade 2 subclinical hypothyroidism. More or less, 90% of individuals with subclinical hypothyroidism have lower than 10 mIU/L TSH values.   

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Subclinical Hypothyroidism Treatment 

and Management

Does subclinical hypothyroidism need to be treated?

For the treatment of subclinical hypothyroidism, most health providers disagreed on whether it needs treatment because of inconsistent studies demonstrating, its effectiveness.

Reasons for not treating subclinical hypothyroidism because it is synthetic (thyroxin hormone), and can potentially cause thyrotoxicosis, which means too much amount of thyroxin hormone in the body. This condition is mostly happened, at ages especially 65 years or older. Additionally, most of the individuals don’t have symptoms. 

According to a theory, subclinical hypothyroidism treatment would possibly prevent from progressing to overt hypothyroidism and decrease the risks of cardiovascular problems. 

Health providers most of the time, recommend that persons who have subclinical hypothyroidism, take a “wait and watch” approach, and decide to not start the treatment to see if the subclinical hypothyroidism resolves on its own.

Though, healthcare providers can suggest treatment in the following cases,

• Middle-aged and young individuals who have mild hypothyroidism symptoms
• People who have TSH values of 10 mIU/L or above.
• Young and middle-aged, individuals who have a risk of cardiovascular diseases

Subclinical hypothyroidism treatment for fertility

TAT (The American Thyroid Association) suggests that individuals allocate female at birth have subclinical hypothyroidism and are having ICSI (Intracytoplasmic sperm injection) or IVF (In Vitro Fertilization), be treated with levothyroxine to gain a TSH (Thyroid stimulation hormones) values of 2.5 mIU/L.

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Treatment

The health provider suggests treatment for subclinical hypothyroidism and prescribes a synthetic hormone medication known as levothyroxine (Levoxyl, Synthroid), which is usually well tolerated and present in the form of pills. 

Before starting levothyroxine therapy, the physician may order another blood test to check the person’s TSH level within three months of the first abnormal blood report. This practice follows because in 60% of individuals who have subclinical hypothyroidism TSH values normalize within three months.

The Health providers likely want to get the person’s blood reports to make sure thyroid levels are in the healthy range while he taking medication. It can cause hyperthyroidism if the levothyroxine dose is too high.   

According to the studies, the facts are most uncertain those with TSH values between 5.1 and 10 mIU/L will get treatment benefits.

In deciding person should be treated or not health provider will take into consideration facts such as 

A person has antithyroid antibodies in the blood and a goiter, because these conditions may indicate the progression to hypothyroidism.

Symptoms, because different people show different symptoms and their lives affect by different intensities of the condition.

• Person’s TSH levels
• Individual’s age
• Individual’s medical family history

Many factors and most of them are individuals out of control elevate the chances of developing subclinical hypothyroidism. These factors are following

Age of an individual;

TSH (Thyroid stimulation hormones) be inclined to rise as age increase, making subclinical hypothyroidism more prevent in elder adults.  

Gender

According to different studies, women are more prone to develop subclinical hypothyroidism as compared to men. There are no, clear-cut reasons behind this fact, but health experts guess, the female hormone estrogen might play an important role.

 Iodine intake

Subclinical hypothyroidism has a tendency to be more established in people that intake enough or surplus iodine, a trace mineral crucial for proper thyroid function. It may help to be known the signs and symptoms of an iodine deficiency.

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Is it possible to get rid of Subclinical 

Hypothyroidism?

Although it is not impossible to get rid of subclinical hypothyroidism by yourselves, it happens often, not always to go away, on its own with time.

Otherwise by medication treatment can be possible, but health specialists don’t always suggest treatment.

Complications may be associated with subclinical hypothyroidism

• Heart complications
• The Association between cardiovascular diseases with hypothyroidism is still being debated. According to several studies, health experts suggest that increased values of TSH may contribute to progressing the following health issues if it’s left untreated,
• High cholesterol levels
• Hypertension (High blood pressure)

In a study, coming across with women and older men, those with a blood TSH value of 7 mIU/L and more, were at twofold the risk or more for having congestive heart failure compared to the group of people who have normal TSH values in the blood. But other studies, could not confirm that fact.

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Pregnancy Loss

For the first trimester, more than 2.5 mIU/L of TSH value is considered to be elevated and 3.0 mIU/L in the second and third trimesters of pregnancy to diagnose subclinical as well as overt hypothyroidism.

A systematic review in 2017, that found the risk of pregnancy complications was noticeable in TPO-positive women with a TSH value greater than 2.5 mIU/L. This risk was not consistently obvious in TPO-negative women until their TSH value elevated 5-10 mIU/L.

According to a study, pregnant women with subclinical hypothyroidism as well as having antithyroid peroxidase (TPO) antibodies have a tendency to highest risk of adverse pregnancy consequences happened if a woman at a lower TSH level than a woman without TPO antibodies, so it is essential to evaluate the status of antithyroid antibodies.

According to another study (The BMJT) that pregnant women with a TSH value between 4.1 and 10 mIU/L who were consequently treated were less possible to have a miscarriage than their corresponding women who were not treated.

Can Subclinical Hypothyroidism be prevented?

In most of cases, nothing is needed to prevent subclinical hypothyroidism or overt hypothyroidism.

However, iodine deficiency can develop or overt hypothyroidism. This happens because the thyroid needs iodine to make thyroid hormones. Iodine deficiency is the most common cause of hypothyroidism globally.

When should you see a doctor about Subclinical 

Hypothyroidism?
 

If, someone’s tests show, subclinical hypothyroidism, in most cases doctors get a “wait and watch” strategy.

If you experience hypothyroidism symptoms like unusual weight gain and fatigue, immediately get your doctor’s appointment and get your checkup done. They probably ask you to do more thyroid blood tests if you have overt hypothyroidism. 

What can you expect if you have Subclinical 

Hypothyroidism?

 

Every case of hypothyroidism is distinctive or unique. Approximately 60% of subclinical hypothyroidism cases within 3 months resolve, on their own.

The risk of subclinical hypothyroidism, moving to overt hypothyroidism is 2-6% per year.

Subclinical hypothyroidism is correlated with an augmented risk of

• Heart problems like congestive heart failure
• Fetal stroke
• Fetal and non-fetal CAD (coronary artery disease) events

If you are feared of these risks and other cardiovascular risk factors, talk to your doctor.

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Diet to Follow

There is not good enough scientific evidence that having or not having certain foods absolutely helps to hold off subclinical hypothyroidism or treat it if anybody has already been diagnosed. However, it is crucial to take the best possible amount of iodine in your diet.

The fact is that too little amount of iodine in the body can lead to hypothyroidism on the other hand too much amount can lead to either hyperthyroidism or hypothyroidism.

The National Institute of Health (NIH) suggests 150 micrograms/per day for adults and teenagers. One cup of low-fat plain yogurt and 1/4th teaspoon of iodized salt gives approximately 50% of the daily iodine required.

Good sources of iodine comprise eggs, dairy products, saltwater fish, and iodized table salt.

The best way to enhance thyroid functions is to eat a well-balanced, nutritious diet.

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Foods that contain Iodine and support 
Subclinical Hypothyroidism Treatment

RDI (Recommended Daily Intake) suggests 150 mcg/day for an adult, and for pregnant women, it needs higher, because the thyroid gland requires iodine to produce thyroid hormones, which play a vital role in the body. 

Eggs

• Egg yolk is an excellent source of iodine because it is supplementary to chicken supply. The amount of iodine in egg yolk varies due to the variation in chicken feed.
• Normally one large egg contains 24 mcg of iodine or, 16 percent of the daily requirement. But a significant amount of iodine comes from egg yolk.

Dairy & Dairy Products

• According to American diets, dairy products are the chief source of iodine.
• The amount of iodine in milk varies significantly based on the use of iodine-holding disinfectant for the period of milking.
• According to some research, 1 cup of milk can give 59 to 112 percent of recommended daily amount of iodine.
• Yogurt is also an excellent source of iodine. 1 cup of yogurt gives almost half of the daily recommended amount.
• Cheddar and cottage cheese also contain iodine but the amount of iodine varies depending on the type. For example, one ounce of cheddar cheese contains about 12mcg while cottage cheese provides 65 mcg.  

 

Iodized Table Salt

• Iodized salts have been sold in grocery stores for decades to help the occurrence of swelling of the thyroid glands or goiters.
• One-fourth teaspoon of iodized salt contains about 71 mcg of iodine, which is 47 percent of the daily recommended iodine intake.
• Due to insist of the chief Health organization to control daily sodium (present in salt) consumption to prevent and treat hypertension (High blood pressure). However salt only appears to elevate the BP (Blood pressure) in a salt-sensitive populations, which is approximately 25 percent. 

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Sea Weed

• Seaweed is a good source of iodine as well as antioxidants. 
• It is rich in vitamins, minerals, and antioxidants and it is low in calories also. Tough, the amount of iodine may vary considerably found on the preparation of seaweed, its type, and the region in which it grew.

There are three popular varieties of seaweed widely used, wakame, nori, and kombu.

Kombu Kelp

• It is a brown seaweed type, available in the marketplace as dried or a fine powder. Usually, kombu kelp is used to make a Japanese soup stock known as Dashi. 
• Kombu kelp may include equal to 2,984 mcg of iodine per seaweed sheet, which is equal to 1 gram. This amount provides nearly 2,000 percent of the recommended daily intake.
• In a survey-based study, seaweed samples taken from various Asian countries for the evaluation of their iodine content found that kombu kelp has, definitely, the highest amount of iodine as compared to other types of seaweed.
• As kombu kelp has the highest amount of iodine, the other fact is that excess iodine intake may lead to thyroid dysfunction but only for those who are sensitive or susceptible, whereas, the majority of the population is well-tolerated.

Wakame

• It is another form of brown seaweed, generally used to make miso soup, and wakame’s taste is sweet.
• The amount of iodine totally depends on where it is grown. Wakame from Asia has high amounts of iodine compared to the wakame from New Zeeland and Australia
• The usual amount of iodine in wakame seaweed from different parts of the world is 66 percent mcg (microgram) per gram or 44 percent of the daily recommended iodine intake.

Nori

• It is a form of red seaweed and a source of iodine, commonly used in sushi rolls. Disparately brown seaweeds contain a lower amount of iodine.
• The amount of iodine in nori fluctuates between 16 to 43 mcg/gm (microgram per gram), or approximately 11 to 29 percent of the recommended daily intake.

Prunes

• Prunes are a source of iodine mostly present in vegetables, and they are plums that have been dried. 13 mcg of iodine or, about 9 percent of the daily recommended intake is provided by five dried prunes.
• Prunes are rich in different nutrients and vitamins, like vitamin A, vitamin K, iron, and potassium.
• Due to the packed nutrients, prunes provide heart support, colon, and weight management. For example, prunes help to decrease the risk of colon cancer and improve heart health and weight management by reducing appetite.
• Prunes also contain a high amount of sorbitol and fiber that’s why they are generally known for helping relieve constipation.

Cod

• Cod is a white fish, which is mild in flavor and subtle in texture. Comparatively, it is low in calories and fat but provides a large variety of nutrients and minerals including iodine.
• 85 grams (3 ounces) of cod has about 63 to 99 mcg or 42 to 66 percent of the daily proposed intake.
• As the Icelandic Food Content Database suggests, fish that is low in fat has the highest amount of iodine.

Tuna

• Tuna fish is a good source of iodine as well as potassium, iron, and vitamin B. It is high in fat and provides low content of iodine as compared to leaner fish varieties, such as cod.
• It is also a high-protein, low-calorie, and iodine-rich food, 3 ounces of tuna offers 17 mcg or 11 percent of the proposed daily intake of iodine.
• Tuna helps to decrease the risk of heart disease because it has omega-3 fatty acids.

Shrimp

• Shrimp is a good source of iodine-rich in protein and low in calories. It provides some significant nutrients such as selenium, vitamin B12, and phosphorus.
• Like other sea foods, shrimp absorb iodine naturally present in the seawater that’s why they are rich in iodine.
• 3 ounces of shrimp provide approximately 35 mcg or 23 percent of iodine of the daily proposed intake.

Lima Beans

• It is a good source of iodine from vegetables but also offers magnesium, fiber, and folate that make the heart healthy.
• Lima beans are generally linked with the famous Native American dish named, succotash, which mixes corn with lima beans.
• One cup of cooked lima beans provides 16 mcg or 10 percent of the daily intake value.
• Due to the fluctuation in irrigation water, soil, and fertilizer, the value of iodine may vary in vegetables and fruits.

Conclusion

Subclinical hypothyroidism turns out when a person gets high TSH (Thyroid stimulation hormones) and, normal T3 and T4 values in a blood test. Generally, it does not cause symptoms and it may or may not require treatment.

Technically subclinical hypothyroidism is not hypothyroidism, but it has the potential to develop into hypothyroidism.

A reason for the development of subclinical hypothyroidism is the reduction in the production of thyroid hormones named thyroxine and triiodothyronine secreted from the thyroid hormone.

Subclinical means a condition that’s not severe enough to cause specific symptoms.

TSH (Thyroid stimulation hormone) also known as thyrotropin, which is released from the pituitary gland, triggers the thyroid to release its hormones, thyroxin (T4) and triiodothyronine (T3). These two hormones are essential for maintaining normal body metabolism.

Subclinical hypothyroidism generally, affects adults, especially among pregnant females and old (more than 65 years old) people, and is diagnosed by thyroid function blood test.

If the healthcare provider suggests levothyroxine (thyroid replacement medication) given orally.

In some cases, iodine deficiency is the reason for subclinical hypothyroidism. Iodine is an important mineral required for the proper function of the thyroid gland.

Seaweed, shrimp, tuna, eggs, and dairy are iodine-rich foods. However, iodized table salt provides an easy way to add iodine to meals.

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