Focus on hypothyroidism
What does hypothyroidism mean?
In Europe, hypothyroidism affects between 0.2% and 5.3% of the general population and it is more common in women, particularly after the menopause. It occurs when the thyroid is no longer able to produce sufficient quantities of thyroid hormones – thyroxine (T4) and triiodiothyronine (T3) – which are fundamental for regulating metabolism and other important functions of our body, such as growth and fertility.
What are the symptoms of hypothyroidism?
The initial symptoms of hypothyroidism can appear very gradually, they are often mild or non-specific, but in time they become increasingly persistent and can consist in:
- weight gain
- tiredness
- muscle fatigue and weakness
- reduced tolerance of physical exertion
- intolerance towards the cold
- dry skin
- hair loss
- brittle nails
- drowsiness and depression
- menstrual cycle irregularities
- fertility disorders
- sexual dysfunctions
- cramps and stiff or swollen joints
- slow or irregular heart rate
- hoarseness, lowered tone of voice
- memory loss
- concentration difficulties
- increase in cholesterol values
- constipation
- fluid retention
The causes of hypothyroidism
Hypothyroidism can be classified into two main categories based on its causes:
Primary hypothyroidism, the most common form, occurs when the thyroid gland is damaged or does not work perfectly and as a consequence does not produce sufficient quantities of thyroid hormones. It can be the result of a congenital thyroid disorder, i.e. one present from birth (congenital hypothyroidism), or acquired (acquired hypothyroidism) as a result of an autoimmune disease (e.g. Hashimoto’s thyroiditis) or a surgical procedure (for example removal of the thyroid gland) or radiotherapy, therapy with Iodine-131, the use of certain medicines or iodine deficiency.
Secondary hypothyroidism, on the other hand, occurs when the pituitary gland, which is located at the base of the skull, does not work properly and does not produce enough TSH, the hormone that, in turn, stimulates the thyroid to produce the thyroid hormones. This condition can be caused by a lesion or tumour that damages the pituitary gland, by a surgical procedure or by radiotherapy to the brain, or by certain genetic diseases.
How do I know if I have hypothyroidism?
Following a general physical examination, in which he/she will assess any symptoms and will palpate your neck, your doctor will prescribe a simple blood test to assess your thyroid function that, in the case of hypothyroidism, will show high levels of TSH (the hormone produced by the pituitary gland that controls the production of the thyroid hormones) and low levels of T3 and T4. This is called overt hypothyroidism.
There is also another form of hypothyroidism, known as subclinical hypothyroidism, in which the TSH levels are outside the normal range, but the thyroid hormones remain normal. In this case, the patient does not usually have any symptoms.
Once hypothyroidism has been confirmed, other tests will be prescribed (for example to detect anti-thyroid antibodies – anti-thyroid peroxidase antibodies (AbTPO), anti-thyroglobulin antibodies (AbTG), and anti-TSH receptor antibodies (AbTR) –, an ultrasound scan, etc.) to analyse the cause and severity of the disease.
What is the treatment for hypothyroidism?
The pharmacological treatment of hypothyroidism consists in replacement therapy with a synthetic thyroid hormone (levothyroxine), which substitutes the hormones the thyroid is no longer able to produce in sufficient quantities. The therapy must be taken orally every day, in most cases in the morning, on an empty stomach, and it is generally well tolerated.
Obviously it will be your doctor who establishes the dose depending on the severity of your illness, TSH and thyroid hormone levels, weight, and medical history. Once the appropriate “target” TSH value has been achieved, the chosen daily dose will be kept constant and, in the absence of complications, it will be sufficient to have laboratory tests once a year.
What are the possible consequences of not treating hypothyroidism?
If hypothyroidism is not diagnosed and treated, it can deteriorate and give rise to various complications, such as, in adults, the formation of a goitre, i.e. an increase in the volume of the thyroid, heart failure, increase in diastolic pressure, peripheral neuropathy or myxoedema (a subcutaneous build-up of fluid that occurs predominantly as a result of severe hypothyroidism). There is also a relationship between untreated hypothyroidism and decreased female fertility, as well as an increase in possible congenital malformations and damage in neonates born to a mother with hypothyroidism.
During foetal life, untreated “congenital” hypothyroidism, i.e. that is present at birth, is responsible for serious physical and cognitive development abnormalities, whereas during childhood (acquired hypothyroidism), it can also cause delays in sexual development. If, on the other hand, diagnosis is early and treatment is adequate, it is possible to compensate for the lack of thyroid hormones, thus effectively controlling the illness and ensuring a good quality of life.
REFERENCES
- Global epidemiology of hyperthyroidism and hypothyroidism. Nat Rev Endocrinol. 2018 May;14(5):301-316.
- Hypothyroidism. Lancet. 2017 Sep 23;390(10101):1550-1562.
- Chaker L, Razvi S, Bensenor IM, Azizi F, Pearce EN, Peeters RP. Nat Rev Dis Primers. 2022 May 19;8(1):30. doi: 10.1038/s41572-022-00357-7. Erratum in: Nat Rev Dis Primers. 2022 Jun 10;8(1):39. PMID: 35589725.
The information provided on the website www.feelthyroid.com is not intended as a substitute for doctor-patient relations or specialist consultations. It is advisable to always consult your doctor and/or a specialist regarding the information and guidance provided.