What is Secondary Hypothyroidism | Difference between Primary & Secondary Hypothyroid

Hi, the inquiring minds who are here to learn about this Secondary Hypothyroid. The name itself sounds like a bit wobbly, huh? Guess what, The reason behind this name is also a bit confusing. So, to understand the concept of secondary hypothyroidism completely, pay serious attention. Anyway, before delving into the concept of studying about secondary hypothyroid; it is of utmost importance that you know about Thyroid gland, then comes the matter of acknowledging the key facts about What is hypothyroidism. This flow of a process to read regarding the secondary hypothyroid makes it a lot easier for you to understand; even without the prior knowledge of medical terms and concepts. But if you think you know about these then wait no more and scroll directly to the topic of secondary hypothyroid.

Brief Introduction About Thyroid Gland

The thyroid gland is one of the major glands in the endocrine system (hormone-producing system). This gland looks after the production of thyroid hormones namely T3(Triiodothyronine) and T4(Thyroxine) which are in turn responsible for the metabolic activities in our body. The thyroid gland is located near Adam’s apple in the front of our throat. The fun fact about thyroid gland is that it resembles the structure of a butterfly.

Difference Between Hypo Thyroid & Hyper Thyroid Mechanism

Generally, We can say that the person is a victim of hypothyroid when the T3 & T4 Hormone Levels are low and TSH is very High.

 In contrast, Hyperthyroid Patients diagnose with high T3 & T4 Levels and Low TSH (Thyroid Stimulating Hormone).

It is easy to diagnose hyper and hypothyroid with blood tests based on the T4 & TSH Levels. Here comes the strange condition which is known as Secondary Hypothyroidism. Let’s see the mechanism in the below sections.

Mechanism Involved In Secondary Hypothyroid

As already said the thyroid hormones are released by the thyroid gland; but the mechanism involved to release these hormones timely and in sufficient amounts is a negative feedback mechanism. This involves a simple fact.

  • When the levels of T3 and T4 are low, Hypothalamus releases TRH which activates the pituitary gland to release the TSH.
  • This TSH acts on the thyroid gland in the production of thyroid hormones.
  • When the levels of thyroid hormones are balanced it sends a negative feedback message to the pituitary gland; which then follows his by sending it to the hypothalamus thus stopping the secretion of TRH.
  • This well-structured mechanism maintains the balance of thyroid hormones required for the body to continue its process of metabolism i.e, breaking down of food into energy.

Hence In secondary Hypothyroid, we can observe that the T3,T4 levels are low along with low TSH (Thyroid stimulating Hormone).

[MUST READ] Information about the TSH levels and range

What is Primary Hypothyroidism?

When the levels of required thyroid hormones are not met, the body fails to do its metabolic activities in its full state. This phenomenon or condition is known as primary hypothyroidism. So, the energy produced is less; (meaning body suffers from fatigue) and also the calories are not efficiently converted into the energy; which means the fats are stored in the body leading to weight gain. These are a part of the hypothyroid symptoms, not the whole list.

[ALSO READ] General Symptoms of Hypothyroidism

What is Secondary Hypothyroidism?

Generally, hypothyroidism is diagnosed with high TSH levels but with secondary hypothyroidism, it is different over the exact opposite.

Difference Between Primary & Secondary Hypothyroidism

Yes, the underactive thyroid test or secondary hypothyroid shows that low TSH levels are found with low levels of T3 and T4 as well.

Where as Primary Hypothyroidism shows low T3 and T4 Hormones and High TSH Levels.

It is a highly well-known fact that the release and production of thyroid hormones is dependant on many factors; such as thyroid gland, hypothalamus, and also the pituitary gland. When the thyroid levels are abnormal then it means that either of the gland involved is malfunctioning; which includes thyroid gland but not limited to it. When this happens, the person faces the thyroid disorders. 

(Quick Note) Causes of Secondary Hypothyroidism

  • So, if the person is showing the symptoms of hypothyroidism and the TSH levels are high, it is a case of primary hypothyroidism; as it is a result of the mistake of the thyroid gland.
  • But, if a person is diagnosed with low thyroid symptoms; and the lab test shows that the TSH levels low apart from the low T3 and T4, then he/she is a victim of secondary hypothyroidism; which is a type of hypothyroidism arisen due to the inability of the pituitary or hypothalamus to produce enough or sufficient signaling hormones such as TSH and TRH.
  • This might owe to the failure of less TSH from pituitary gland because of a tumor. 
  • The people who are most affected or the people who will be affected the worst are the ones with a history of pituitary or hypothalamus disorder.
  • The other risk factors for secondary hypothyroid include old age, gender etc.
  • Finally, whatever the cause is or whatever type of hypothyroidism is the reason; one point that everyone needs to learn is to get early detection and treatment. 

[Know More] What is Myxedema Coma?

Hyperthyroidism Vs Secondary Hypothyroid

Wait there’s more, you need to know what is that small difference that makes hyperthyroidism different from secondary hypothyroidism; as both have and show the low levels of TSH in the laboratory tests. This difference all lies in the fact that, when the person has low TSH levels in the blood but the free T3 & T4 or general T3 and T4 are in increased amount; then the person is diagnosed with hyperthyroidism. This doubt arises because of the fact that both secondary hypothyroid and hyperthyroidism are diagnosed with low TSH levels in the serum of blood. 

[Also Check] What is Hyperthyroidism?

Secondary Hypothyroidism Treatment

Many specialists suggest for thyroid hormone replacement therapy with Thyroxine. Also, there is an availability of thyroid hormone preparations in this medicine world. So your doctor may give you the synthetic preparations of hormones that include T4 (l-thyroxine), T3 (liothyronine), and the combinations of the 2 synthetic hormones. So, If you are diagnosed with secondary hypothyroidism, then you will be treated with Levothyroxine.

However, the dosage may be given to you depending on your age, body mass, and other factors taking into consideration. Most of the young and middle-aged patients were given the dosage of thyroxine that is higher when compared to the patients who are with cardiovascular diseases and older in age. However, the dosage will be changed until your thyroid gland achieves the balancing levels of hormones. So this is how the patients who are diagnosed with secondary hypothyroidism will be treated.

Final Note

So, guys, I hope it is very clear and explicit about secondary hypothyroid and the consequences it has. I think if you have read the entire topic, then it would be more obvious about the difference between primary hypothyroid and secondary hypothyroid and also how they are different. Now that this particular discussion has come to an end; I request you guys to share any information regarding secondary hypothyroid that you know of. If not, then feel free to visit My Thyroid Problems to know or read about the thyroid gland, its functions and the different types of thyroid disorders or thyroid problems associated with the production of thyroid hormone.

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