The most common thyroid dysfunction, hypothyroidism, has “nonspecific” symptoms, caused by slowing physiological functions.
So small, but so important. It is the thyroid: a gland, about five centimeters in diameter and weighing between 10 and 50 grams, which through the production of hormones determines the rhythm of metabolism, regulates the growth of the organism and the development of the central nervous system.
Since hormones influence numerous physiological functions (cerebral, vascular, reproductive, respiratory and responsible for the production of red blood cells) the poor functioning of the thyroid affects the state of health of the individual causing a general slowdown of metabolic processes.
What is thyroid
Located at the border between the larynx and trachea, at the base of the anterior portion of the neck, the thyroid consists of two symmetrical lobes, connected to each other by a small isthmus, which give it the typical “butterfly” shape.
The activity of the thyroid gland takes place under the control of the pituitary. This releases the hormone TSH (thyroid-stimulating hormone), necessary to stimulate the gland to produce the thyroid hormones T3 (triioodiothyronine) and T4 (thyroxine), in variable amounts depending on their concentration in the blood. When levels drop, TSH causes the thyroid to release more of them. When there is an excess of thyroid hormones in circulation, the pituitary gland rests.
The thyroid also produces the hormone calcitonin, which is useful for maintaining bone mass and fixing calcium in the bones. Calcitonin levels higher than normal can be the indicator of a neoplasm affecting the gland, and must therefore always be investigated.
Beware of iodine deficiency
Thyroid hormones consist mainly of iodine; for the thyroid to function properly and produce adequate amounts, it is therefore necessary to take the right amount of iodine with the diet. The daily requirement for an adult is 150 micrograms, for pregnant women it rises to 220. However, the iodine content in food and water is very variable and often too low in relation to the body’s needs.
Iodine deficiency is still considered a public health problem, especially in developing countries. According to data from the OSNAMI report (National Observatory for the Monitoring of Iodine Prophylaxis in Italy) of 2014, iodine deficiency affects almost 30% of the population worldwide and 12% of Italians are affected by goiter. The correct intake of iodine is easily achieved by replacing the common table salt, of which a moderate consumption is still recommended, with salt enriched with iodine.
One gram of iodized salt contains about 30 micrograms of iodine: to reach 150 micrograms it would be sufficient to take five grams of salt a day. It should be borne in mind, however, that cooking reduces the iodine content by about 50% and that much of the salt taken through the diet comes from processed foods that do not contain iodized salt. A varied diet, which also includes good sources of iodine, such as milk and sea fish, can ensure the correct intake of this mineral.
Thyroid dysfunction: hypothyroidism
Functional alterations of the thyroid can manifest themselves with a production of T3 and T4 hormones in excess (hyperthyroidism) or in defect (hypothyroidism) compared to the body’s needs.
Hypothyroidism is the most frequent alteration of thyroid function. The severity of the condition depends on the degree of hormone deficiency, the stage of life at which it occurs and the time lag between its onset and diagnosis. Women are more affected than men and it becomes more frequent with advancing age. In the over sixty-five, the share of individuals with overt hypothyroidism varies between 2% and 5%, while another 5-10% presents a sublinic form.
In 95% of cases, hypothyroidism originates from reduced thyroid function (primary hypothyroidism). Secondary hypothyroidism, much rarer, can instead be caused by reduced stimulation of the thyroid by the pituitary, also following a malfunction of the hypothalamus.
The most common cause of hypothyroidism is Hashimoto’s thyroiditis, an autoimmune disease characterized by the presence of antibodies, called anti-thyroperoxidase, directed towards the main enzyme responsible for the synthesis of thyroid hormones. In practice, these antibodies attack the cells of the thyroid itself, causing their progressive inflammation and destruction, thus reducing their functionality.
Hypothyroidism can also be due to external causes, such as removal of the thyroid, radioactive iodine therapy and taking medications such as amiodarone, used to treat cardiac arrhythmias, or lithium.
In one case every 2,500 births, hypothyroidism is present from birth (congenital hypothyroidism) due to an altered development of the gland, its total absence or its localization in a location other than normal. In all these cases, thyroid hormone deficiency exposes the fetus to damage to the central nervous system that manifests itself with severe forms of mental retardation. There are no characteristic signs and symptoms that indicate the presence of congenital hypothyroidism at birth, which is why newborn screening has been practiced for years.
Sometimes hypothyroidism, especially in severe forms, can manifest itself with the appearance of goiter. The thyroid increases in volume in an attempt to compensate for thyroid hormone deficiency, and small nodules form on the surface of the gland. When large, the goiter can compress surrounding tissues causing coughing, swallowing problems, difficulty breathing or feeling of compression on the throat. In pregnancy, goiter can lead to abnormalities in the brain development of the fetus. People with goiter are also at increased risk of developing thyroid cancer.
Symptoms of hypothyroidism
The reduction in the concentration of thyroid hormones in the blood causes a slowdown in physiological functions, with less energy consumption, less cell turnover, reduced oxygen transport in the cells. The symptoms of hypothyroidism are related to a general slowing down of physiological processes, but due to their non-specific nature they are not always immediately attributable to this condition. The first signs should be detected by the family doctor, but it is then the endocrinologist specialist who makes the diagnosis and starts the treatment.
Among the most common symptoms are swelling of the face and eyelids, cold and dry skin, hair loss that also becomes more fragile. From a cognitive point of view, concentration and memory difficulties, slowness in speaking may appear. At the cardiovascular level, rloosening of heart rate, hypotension, possible alteration of cholesterol and triglyceride values. Other possible manifestations arestanchezza, depression, muscle weakness, weight gain, poor sweating and feeling cold. In women, alterations in the menstrual cycle may occur.
Diagnostic procedure
The diagnosis of hypothyroidism is based on:
- on the patient’s medical history
- on a visit that involves palpation of the thyroid to detect the presence of goiter and any nodules
- on the dosage of hormones FT3, FT4 and TSH.
If the TSH is reduced, it means that the gland is working too well; On the contrary, if it has high values, the thyroid is working too little. In full-blown hypothyroidism, a higher than normal TSH value is associated with low FT3 and FT4 values. When, on the other hand, these are normal, despite an excessive TSH value, it is subclinical hypothyroidism, in which no obvious signs and symptoms have yet appeared.
The reference values for TSH (expressed in mlU/l, thousandths of international units of biological activity per litre of blood) in adults are:
Suspected hyperthyroidism | < 0,5 mlU/l |
Normal range | 0.5-4 mlU/l |
Suspected hypothyroidism | > 4 mlU/l |
The path of diagnosis is completed by instrumental examinations, the most common and used of which is ultrasound. This allows you to evaluate the structure of the thyroid, define its shape and size and identify any nodules and cysts. In addition, the measurement of blood pressure, the frequency of heartbeats, the appearance of the skin should also be considered in the assessment. Finally, to establish the autoimmune origin of the dysfunction, the test for autoantibodies is also generally prescribed.
Therapy
Hypothyroidism is a chronic and irreversible disease, but easily treatable thanks to the oral intake of thyroid hormone, a replacement therapy to be followed scrupulously throughout life. In the past dry thyroid was administered, today the drugs used are based on thyroxine and triioodiothyronine.
The dosage varies according to the patient’s weight, but is fine-tuned gradually, starting with a dose lower than that needed and increasing it progressively. At this stage it is important that the patient detects any symptoms resulting from the effect of thyroid hormones. If anxiety, tachycardia and diarrhoea appear, it may be appropriate to reduce the dose; If only the typical symptoms of hypothyroidism continue to be present, the doctor may proceed to increase it. Since it is a chronic therapy, thyroid function should be monitored through periodic blood tests.
From a practical point of view, it is important that medications are taken in the morning on an empty stomach. You must also wait at least 40 minutes before having breakfast; Some foods, in fact, affect the absorption of the active ingredient. Among these, coffee, soy, grapefruit and milk are particularly at risk of hindering, delaying or slowing down the availability of thyroxine. Even cereals, especially whole grains, slow down the absorption of the drug in the intestine due to their high fiber content.
Some commonly used drugs also reduce the effectiveness of substitution therapy. These are proton pump inhibitors for the treatment of gastritis, those for gastroesophageal reflux, anticoagulants and drugs containing aluminum.
Joycelyn Elders is the author and creator of EmpowerEssence, a health and wellness blog. Elders is a respected public health advocate and pediatrician dedicated to promoting general health and well-being.
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