Ultra-light (barely 15 g), the thyroid nevertheless weighs in the balance. It produces hormones, thyroxine (T4) and triiodothyronine (T3) which regulate almost all of the body’s vital functions. Weight gain, age, pregnancy, menopause… Just a little thing is enough to disrupt this little butterfly-shaped gland located at the base of the neck.. Fortunately, its exploration has never been so easy: a palpation, a blood test for thyroid-stimulating hormone (TSH) – this is also a hormone secreted in the brain by the pituitary gland to regulate thyroid hormones – or even an ultrasound is enough. to highlight the presence of hypertrophy (goiter), a nodule or dysfunction (hypo or hyperthyroidism). 2% of the population is affected by thyroid disease. The main one, hypothyroidism, affects 1 to 2% of the population, and hyperthyroidism, around 0.4%*.
However, do we need to treat all of these cases? The change in the formula of Levothyrox in 2017 opened the debate. Side effects caused by the new formulation have in fact led many patients to stop the medication, without suffering from this therapeutic withdrawal. Proof that support was ultimately not necessary… This surprising observation pushed the High Authority for Health (HAS) to issue new recommendations. Objectives: to harmonize medical practices and not multiply unnecessary examinations and treatments. Here are the highlights.
*Source: HAS 2023
Hypothyroidism, to be assessed on a case-by-case basis
Hypothyroidism is characterized by a reduction in the secretion of thyroid hormones and a slowdown in the body’s vital functions. The majority of them, including the most common, Hashimoto’s thyroiditis, are of autoimmune origin: the body wrongly produces antibodies which attack the thyroid.
People at risk. Hypothyroidism occurs mainly among women, with an incidence increasing between 35 and 60 years of age. The risks are increased in the event of a family history of dysthyroidism, autoimmune diseases (type 1 diabetes, Crohn’s disease, etc.), pregnancy or taking certain medications.
Symptoms. Of varying intensity, they are very numerous and non-specific: fatigue, nervousness, depressive symptoms, hair loss, menstrual cycle disorders, etc.
The diagnosis. “It is based on a simple blood test in the event of suggestive symptoms, but also before or at the start of pregnancy in women at risk of developing hypothyroidism or difficulty conceiving “, explains Professor Jean-Michel Petit, diabetologist endocrinologist at Dijon University Hospital. The doctor then draws up a prescription, in which he lists the different dosages to be carried out in cascade. The first is that of TSH. A high level signals hypothyroidism : it indicates that the pituitary gland must secrete more TSH to force the thyroid to produce more hormones. The information is not necessarily worrying in itself, but it forces the biologist to continue his investigations: from the same blood sample, he measures the most abundant thyroid hormone, free tetra-iodothyronine (T4L). , to determine whether it is gross hypothyroidism (normal T4L) or proven hypothyroidism (T4L below normal). The determination of antithyroperoxidase antibodies (anti-TPO) will confirm the autoimmune nature of hypothyroidism in cases of low T4L.
The treatment. Proven hypothyroidism, and certain crude hypothyroidism, is treated by taking a replacement hormone: levothyroxine. Treatment monitoring is based on annual TSH testing. In case of pregnancy, levothyroxine doses should be increased by 25% to 30%.
Hyperthyroidism, no systematic treatment
This dysthyroidism is characterized by an increase in hormonal secretions and an acceleration of the body’s vital functions.
People at risk. Hyperthyroidism generally appears between the ages of 40 and 60 and mainly affects women. In 70% of cases, it is caused by an autoimmune disease, Graves’ disease. It can also be caused by a nodule that secretes too much thyroid hormone (toxic nodule) or by taking certain medications.
Symptoms. Here again, they are numerous and not very specific: palpitations, tachycardia, irritability, anxiety, weight loss, heat intolerance, etc.
The diagnosis. The TSH dosage is sufficient to diagnose hyperthyroidism. As with hypothyroidism, the doctor will prescribe biological tests to be carried out in sequence from the same blood test, to complete the diagnosis (frust or proven hyperthyroidism) or determine the cause of the disease.
The treatment. In case severe hyperthyroidism (low THS and normal T4L), simple monitoring is most often sufficient. In case of proven hyperthyroidism (low HRT and T4L higher than normal), treatment with synthetic antithyroid drugs is essential. Once thyroid function is restored, this treatment can be stopped in Graves’ disease, but recurrences are common. The different therapeutic options are then discussed on a case-by-case basis: resumption of medical treatment, use of radioactive iodine (iritherapy) or surgery (thyroidectomy). These last two treatments are immediately proposed in the presence of toxic nodules.
Thyroid nodules, usually not touched
“Nodules are to the thyroid what moles are to the skin“, explains Dr Livia Lamartina, oncologist-endocrinologist at Gustave Roussy (Villejuif). The vast majority of them correspond to clusters of thyroid cells without any particular function (cold nodule) or simple balls of liquids (cysts). Some, more rare, secrete thyroid hormones (so-called hot or toxic nodules).
People at risk. Nodules are very common in the general population, particularly women, and their frequency increases with age. In their fifties, it is detected incidentally in more than 50% of women who have an ultrasound.
Symptoms. Most often painless, nodules do not cause symptoms and are discovered by chance, following a medical examination (palpation or imaging). When size (or number) matters, it can interfere with swallowing, breathing or speaking.
Exams. “In 90% of cases, thyroid nodules are benign and do not require exploration“, indicates Dr. Lamartina. Ultrasound is only performed in cases of doubt. It allows the characteristics of the lump to be analyzed and a score of 2 to 5 to be assigned to it, corresponding to an increasing risk of malignancy ( category 1 meaning an absence of nodule). If the nodule is suspicious and measures more than 1 cm, a fine aspiration is recommended. Microscopic study of the sample taken will clarify its nature.
Thyroid cancers, from simple monitoring to ablation
Slowly evolving, this cancer (more than 10,000 cases per year) is part of those who are best cured, without relapse. Not all require surgery.
People at risk. Thyroid cancer affects women 2 to 3 times more than men. Most often, no cause is found. However, certain factors are predisposing: exposure to irradiation in childhood (accidental or linked to radiotherapy), history of thyroid cancer in a family member, or certain rare genetic diseases.
Symptoms. Most of the time, this cancer does not manifest itself by any particular sign. Its discovery is fortuitous. The disease can nevertheless manifest itself by the appearance of a nodule in the thyroid, the rapid increase in the volume of a goiter, the appearance of a lymph node in the neck, difficulty swallowing, breathing or talk.
The diagnosis. Ultrasound and cytopuncture are the reference examinations. Others may be necessary to determine the extent of the cancer (laryngoscopy, scintigraphy, PET scan, etc.).
The treatment. It depends on the results of ultrasound, fine aspiration and the size of the nodule. If it is less than 1 cm, active surveillance will be put in place. “These micro-cancers remain stable for a very long time without evolving., reassures Dr Livia Lamartina. Beyond 1 cm, surgery is recommended. It is limited to partial removal of the thyroid (lobectomy) if the size of the nodule is less than 2 cmbut at a total ablation (with lymph node curettage) if it is greater at 2 cm. Generally speaking, the risks of recurrence are rare. If the pathological examination of the removed tissue confirms the malignancy of the nodule with a risk of relapse, the patient can undergo radiation therapy.
Which specialist to consult?
The general practitioner remains the primary care doctor. It is he who prescribes additional examinations (TSH dosage) and manages hypothyroidism. Consultation with an endocrinologist, specialist in hormonal imbalancesis recommended in certain cases of delicate diagnosis, dosages at the limits of normal values, pregnancy or the presence of suspicious nodules.
Medications, watch out for interactions
If taking levothyroxine, be wary of self-medication. Certain medications containing iron and calcium salts can indeed modify the absorption of this synthetic thyroid hormone. Same thing with vitamin cocktails, which are best taken 2 to 4 hours before or after the medication. Finally, in the case of hyperthyroidism, be careful with food supplements based on algae, which can increase the overload of the thyroid. It is in fact from the iodine contained in our food (fish, seafood, algae) that the thyroid produces its hormones.