Hypothyroidism or hyperthyroidism: how to tell the difference?

The thyroid is a butterfly-shaped gland, located in the neck below the Adam’s apple, which creates the thyroid hormones T3 and T4. « These hormones have an important role: they regulate many body functions and act on multiple organs in the body: on the heart, on the basal metabolism which is a bit like the ‘boiler’ of the body, on the digestive tract … » explains Dr. Jean-Michel Borys, endocrinologist. But also on bone growth, temperature regulation, stimulation of tissue oxygen consumption… And when there are not enough or too few hormones produced, the whole body is out of order.

« When the thyroid does not work enough, we speak of hypothyroidism: it is as if we pressed the slow motion button, and the whole body began to operate in slow motion », says Dr. Borys. Symptoms such as:

• A weight gain and one swellingt everywhere in the body;
• A great fatigue ;
• A slow heart rate : the heart beats slowly;
• A chilliness : « the famous ‘boiler’ of the body does not work enough so we are very cautious: we can be in the middle of August and be cold », he notes;
• A slowing hair growth ;
• A cerebral slowing : « it takes more energy and time to think, to achieve intellectual things »he says;
• A physical slowdown (we get out of breath more quickly, for example);
• The intestines also work slowly, which can induce constipation;
• A dry skin.

“Hyperthyroidism is the opposite: pressing the acceleration button, continues Dr. Borys. Result: the majority of body functions are accelerated. Symptoms such as:

• A weightloss despite a normal appetite;
• A big fatigue ;
• A increased heart rate : the heart beats quickly;
• A transit acceleration which can cause diarrhoea;
• We have all the time hot ;
• We are often agitated, nervous, anxious ;
• « In some forms of hyperthyroidism, you may see other signs, such as eyes that stick out (exophthalmos), for example, which is most often found in Graves’ disease », adds the endocrinologist.

One can also see a depressed state, a irritabilityand one delirium in the elderly.

« During hyperthyroidism, everything is accelerated, while with hypothyroidism, everything is slowed down. These two disorders are opposed cause very different symptomsas we have just seen, explains Dr. Borys. It is therefore very simple to distinguish between the two diseases. The only common point in terms of symptoms? « It’s here fatigue », he answers. “Whether it is hypothyroidism or hyperthyroidism, we are extremely tired in both cases”.

Another common point: in most cases, hypothyroidism and hyperthyroidism are both autoimmune diseases.

The Hashimoto’s disease Where youHashimoto’s hyroiditis is the most common cause in hypothyroidism. In this autoimmune disease, organism attacks thyroid cells. « The body, on a particular genetic ground, produces antibodies which attack the thyroid gland, which, attacked, ends up ‘dropping’ and no longer produces enough hormones », explains Dr. Borys.

The Graves disease is most often involved in hyperthyroidism. « Stress is a triggering factor: in the family, it triggers the production of anti-TSH receptor antibodies called TRAKwhich come to stimulate the thyroid gland to make it produce lots of hormones », he continues.

« Diagnosis is first clinical« , notes Dr. Borys. « Then we make a TSH test through a blood test. TSH is a hormone made by the pituitary gland, which is located in the brain, and controls virtually every gland in the body, including the thyroid gland. By secreting TSH (Thyroid Stimulating Hormone in English), the anterior pituitary gland of the brain regulates the levels of T3 and T4 hormones in the blood.

« If you lack thyroid hormone (hypothyroidism), the signal goes to the brain saying ‘there is not enough thyroid hormone’ and the brain increases the production of TSH. The TSH level is therefore high in case of hypothyroidism« , explains the endocrinologist.

« In case of hyperthyroidism, it’s the opposite: you have too much thyroid hormone, the signal goes to the brain saying ‘there is too much thyroid hormone’ and the brain lowers the production of TSH. The TSH level is therefore low in case of hyperthyroidism« .

Once the blood test is done, the TSH level in the blood is checked. « Below 0.1 mIU/L, It’s a sign of hyperthyroidism. » notes Dr. Borys.

Once the blood test is done, the TSH level in the blood is checked. « Above 4 mIU/L is a sign of hypothyroidism », he said.

« To treat hypothyroidism, we are going to bring hormones to the body thanks to a molecule called L-thyroxine Where Levothyroxine : it’s the drug we all know as Levothyrox », says the endocrinologist. L-thyroxine is the same molecule that the body makes« It is somehow a ‘natural’ drug because it reproduces exactly what our body produces – and substitutive, because it is not the chemistry that corrects something, but the molecule that replaces what is missing ».

To note :« Levothyrox itself does not cause any side effects. It was the drug coating (excipients) that caused them. These excipients poorly tolerated by some people and have been modified », adds Dr. Borys. Hypothyroidism, in the vast majority of cases, requires lifelong treatment.