Last summer, a drug hitherto unknown to the general public made headlines. Following a formulation change by the manufacturer, Levothyrox® has caused unpleasant side effects in some patients. On this occasion, we learned that 3 million French people take this drug daily. But what is it for? Levothyrox® is one of the trade names for levothyroxine, the synthetic hormone and copy of thyroxine, one of the hormones produced naturally by the thyroid. It is a replacement therapy mainly used to alleviate hypothyroidism, that is to say the slowing down of the functioning of thyroid.
A vital gland
This small gland of about twenty grams located in the throat, just under the Adam’s apple, may be discreet, it is nonetheless vital. From the iodine in the diet, it makes hormones (thyroxine, or T4, and triiodothyronine, or T3) that help regulate heart rate, body temperature, blood sugar, the sleep, the mood or the weight. At the pregnant woman, it plays an essential role in the brain development of the baby. In children, it participates in growth and, in adolescents, it is involved in the onset of puberty.
Ultra-precise dosages
If the quantity of T3 and T4 hormones can be measured by a simple blood test, the TSH test, produced by the pituitary gland, is the most common test. This hormone reflects the functioning of the gland (see opposite) and is more reliable in spotting possible disturbances. Normally, TSH fluctuates between 0.4 and 4 mIU / L (milli-international units per liter of blood), but this range is only indicative, as it can vary from person to person and even from day to day. to the other in the same person. It is also important to make sure that the disease is linked to the thyroid, and not to the pituitary gland.
herself. These precautions taken, it is considered that, if the TSH level is above average, the thyroid is weak. If it is below (and even sometimes undetectable), it is on the contrary that the thyroid is racing.
Regulation of thyroid hormones
A loop system
the thyroid function is under the control of a gland located at the base of the skull, the pituitary gland, itself regulated by a gland in the brain, the hypothalamus. Normally everything works in harmony. But when an imbalance sets in, more or less, clinical signs appear.
1. Stimulation
When the level of thyroid hormones in the blood drops, the pituitary gland sends out a thyroid stimulating hormone called thyroid stimulating hormone (TSH).
2. Production
The gland makes thyroid hormones. For that, she needs iodine.
3. Decrease
When hormone levels are good, the thyroid sends a signal to the brain to calm TSH production.
The two frequent imbalances
Hypothyroidism, the gland works in slow motion
Symptoms
•Tired
• Chilliness
• Moderate weight gain
• Signs of depression
• Slow heart rate
•Constipation
•Cramps
•Dizziness
• Decreased thirst
• Decrease in libido
•Infertility
What treatments?
• Levothyroxine
To compensate for the lack of thyroid hormones, and in particular that of thyroxine, it is necessary to take levothyroxine (this is the famous Levothyrox® …). It will then be transformed into T3 by the body itself, according to its needs.
Hyperthyroidism; the gland is over-revving
Symptoms
• Weight loss despite increased appetite
•Muscle wasting
• Increased heart rate
• Feeling of always being hot
• Heavy sweating
•Irritability
•Diarrhea
• Bulging eyes
• Tremor of the fingers
• Extreme intolerance to stress
What treatments?
• Synthetic antithyroid drugs. These drugs are sometimes combined with beta blockers to slow the heart rate. The treatment is spread over a period that varies from 6 to 18 months.
•Radioactive iodine
It can be prescribed in case of contraindication to drugs or in certain forms of hyperthyroidism. Captured by the cells of the gland, iodine “deceives” the thyroid, which then stops production.
• Thyroid removal
It is considered in the event of recurrent hyperthyroidism or large goiter. It then requires taking thyroid hormones for life.
Practical information
Keeping your thyroid in good shape …
With foods rich in iodine
According to the Inca2 study on the nutritional habits of the French, the average iodine consumption is 126 µg / day, slightly below the recommended daily intake (150 µg / day). Posted online by ANSES (National Health Security Agency), the Ciqual * table allows you to find out which foods contain the most. For iodine, it is the dehydrated algae that comes first. Unsurprisingly, they are followed by other seafood: iodized salt, cod liver, squid and fish such as salmon, mackerel, haddock and haddock.
* Food quality information center: pro.anses.fr/TableCIQUAL
By quitting the cigarette
Smoke from tobacco contains thiocyanates, molecules that disrupt the functioning of the thyroid. Hyperthyroidism is therefore more common in smokers, and its symptoms are more marked: the risk of presenting an exophthalmos (bulging eyes) is also higher in them.
Smoking can also interfere with the action of medications prescribed for thyroid disorders. Better to quit smoking. To achieve this, do not hesitate to seek help from your pharmacist, doctor or addictologist in an anti-smoking consultation.
Who should be consulted?
• A general practitioner
Palpation of a lump in the throat, fatigue, change in intestinal transit or appetite, loss of weight or weight gain, chilliness or difficulty in withstanding the heat, depression or irritability … this may be the sign a thyroid disorder. Talk to your doctor, who will prescribe a thyroid checkup if necessary.
• An endocrinologist
He’s the hormone specialist. The general practitioner refers his patient to him if he deems it necessary.
• A cardiologist
If thyroid disorders have consequences on the heart: palpitations, slow heartbeat …
• An ophthalmologist
In case of hyperthyroidism accompanied by eye problems.
Useful contacts
• A toll-free number: 0 800 97 16 53
Dedicated to Levothyrox®, it responds to patients who wonder about the risk of side effects due to the new formula. Monday to Friday, 9 a.m. to 7 p.m. (free call).
• solidarites-sante.gouv.fr/soins-et-maladies/signalement-sante-gouv-fr
At this address, you can report an undesirable effect related to taking medication (Levothyrox® or other), whether you are a
individual or health professional.
The Medicines Agency website ensures regular monitoring of health products and devotes a section to Levothyrox®.
• www.asso-malades-thyroide.fr
The French Association of Thyroid Patients takes stock of the treatments and gives the floor to specialists.
This open and free discussion forum (more than 18,000 registered users) gave birth to the association Vivre sans thyroïde.
Two practical guides
• Answers from a specialist
Everything you need to know about thyroid diseases and their influence on the social life of patients: origin, symptoms and especially treatments, not always easy to control.
“The thyroid makes us see all the colors”, Dr Valérie Foussier, ed. Josette Lyon, € 17.
Pollution, stress, tobacco … advice on taking care of your thyroid on a daily basis, with a coaching program, adapted recipes and personalized menus.
“Protect and treat your thyroid”, Dr Pierre Nys, ed. Leduc.s, € 18.
A free app
e-thyroid
Designed by the association Living without thyroid, with the support of the Bayer laboratories, this application is a real logbook allowing to record its results of analyzes (T3, T4, TSH …), to program alerts to properly take their treatments and note their medical appointments. Available on the App Store and Google Play.
Read also:
Phthalates disrupt the thyroid of little girls
Boost your thyroid without medication
What are the treatments for hypothyroidism?
