What is the difference between euthyroid, clinical, and subclinical hypothyroidism?

Have you ever read your lab results, and in the comments you see the words “euthyroid”, “clinical” hypothyroidism or “subclinical” hypothyroidism and wondered what it means?

Understanding these terms are important, as it may impact the treatment approach your doctor takes.  Le’ts have a look at these terms, and what it means in term of the typical treatment approach: 

Clinical or overt hypothyroidism

This is when your TSH levels are above the lab’s reference range, and your Free T4 levels are below the lab’s reference range [1]. 

The allopathic doctor will place you on hormone replacement therapy, and the standard approach is to give you T4 hormones, called levothyroxine.  Brand names include Eltroxin and Euthyrox in South Africa, and may have different names (e.g. Synthroid) in other countries.

Subclinical hypothyroidism

This is when your TSH is elevated, but your Free T4 levels are still within the normal range [1].

Patients typically experience hypothyroid symptoms (such as weight gain, hair loss, low libido, exhaustion). The problem is that the allopathic medicine guidelines do not indicate hormone replacement therapy unless the T4 levels are below the lab’s reference range.

Therefore, many doctors will not give T4 hormone pills to patients, and doctors may actually tell patients to “wait and come back in a few months”, until the T4 levels are below the lab’s reference range. Only then are they likely to prescribe T4 hormone medication.

Euthyroid

This is the term used when the TSH level is back within the lab’s normal range, and therefore the thyroid hormone balance is restored within the body [2].

Interestingly, this term is based on the TSH level, and not based on measuring if there are actually sufficient Free T4 or Free T3 levels in your blood, or even if you are symptom-free.

And herein lies the problem. You can have a normal TSH, and still be hypothyroid. Hypothyroidism is more complex than just having a normal TSH.

Adele du Rand

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