Thyroid examinations

Generality

Thyroid examinations are diagnostic tests that allow the identification of thyroid gland pathologies. Thanks to thyroid tests, doctors can therefore identify conditions such as hyperthyroidism, hypothyroidism, thyroid nodules, thyroid cancer, goiter, Graves' disease and thyroiditis.

In the list of thyroid exams, there are: visual and palpatory examination of the thyroid, the quantification of blood levels of thyroid hormones T3 and T4, and pituitary hormone TSH, thyroid ultrasound, thyroid autoantibody test, thyroid scintigraphy and the needle biopsy of the thyroid.

Short anatomical and functional revision of the thyroid

The thyroid is an unequal glandular organ, located in the anterior region of the neck, at the base of the throat .

Similar in shape to a butterfly, this gland plays a very important physiological role; it has the task of regulating:

Body metabolism (for example, affects oxygen consumption; controls the synthesis and degradation of cholesterol; stimulates lipolysis and lipogenesis; increases glycogenolysis and gluconeogenesis, etc.);
Skeletal and cerebral development, starting from fetal life;
Protein synthesis;
The development of the skin, the hair apparatus and the genital organs;
The heartbeat;
Body temperature;
The hematopoiesis.

For the correct performance of all these regulatory activities, the thyroid resort to 3 hormones, which she herself produces and pours into the blood; these 3 hormones - on whose production the hypothalamic hormone TRH and the pituitary hormone TSH play a decisive role - are: triiodothyronine (also called T3 ), thyroxine (also called T4 ) and calcitonin .

The dual ability to produce and inject hormones into the circulatory stream is essential to bring the thyroid back into the list of endocrine glands in the human body.

Figure (of the thyroid): the thyroid resides on the border between larynx and trachea, in anterior position with respect to both these structures.

On the thyroid are recognizable two side portions, called lobes (left lobe and right lobe), and a central portion, called isthmus.

Typically, the thyroid gland weighs about 20 grams; in the course of life, however, its weight may undergo variations, due to certain special events such as puberty, menopause, pregnancy, menstruation, breastfeeding, etc.

What are thyroid tests

Thyroid examinations are the diagnostic checks used to establish the state of health (anatomy, functionality, abnormalities, etc.) of the thyroid gland.

The list of thyroid exams includes:

Visual and palpatory thyroid examinations;
The quantification of the blood levels of thyroid hormones T3 and T4 as well as of the pituitary hormone TSH;
Thyroid ultrasound;
Thyroid autoantibody test;
Thyroid scintigraphy;
The thyroid biopsy.

Indications

Thyroid tests are used in the diagnosis of thyroid disease .

Among thyroid diseases, there are more or less known conditions, such as:

The pertiroidism . It is the direct consequence of an overactive thyroid that produces thyroid hormones even when there is really no need for it. In other words, hyperthyroidism occurs when the thyroid gland produces a quantity of hormones that is greater than the body's needs.
There are 4 different forms of hyperthyroidism: primitive hyperthyroidism, secondary hyperthyroidism, tertiary hyperthyroidism and iatrogenic hyperthyroidism;
Hypothyroidism . It is the exact opposite of hyperthyroidism. Therefore, it is the direct consequence of a thyroid that is not very active and does not produce quantities of thyroid hormones able to satisfy the needs of the organism.
There are 4 different subtypes of hypothyroidism: primitive hypothyroidism, secondary hypothyroidism, tertiary hypothyroidism and iatrogenic hypothyroidism
The goiter . It is the generalized enlargement of the thyroid. Its onset can be associated with a variety of problems, including hyperthyroidism and hypothyroidism.
There are various types of goiters, including: congenital goiter (ie present from birth for genetic reasons), sporadic goiter (due for example to incorrect pharmacological assumptions), endemic goiter (from lack of iodine in the diet), goiter from pregnancy, goiter from thyroiditis, goiter from nodule or cancer of the thyroid and goiter with toxic adenoma.
Basedow's disease (or Graves' disease ). It is a known medical condition that consists of the combination of hyperthyroidism and goiter.
Thyroid nodules . They are benign, slow-growing tumors that, in some particular circumstances, can cause different health problems.
Thyroid cancer . It is the malignant thyroid tumor and represents one of the main reasons for resorting to thyroidectomy, which is the thyroid removal surgery;
Thyroiditis . It is inflammation of the thyroid. There are various types of thyroiditis, including Hashimoto's thyroiditis (autoimmune disease), postpartum thyroiditis, subacute thyroiditis and acute thyroiditis.

Thyroid diseases are very common conditions in the general population; according to statistics from the WHO (World Health Organization), in fact, they would affect more than one billion people worldwide.

In the presence of what symptoms is it good to resort to thyroid tests?

As can be easily understood, a doctor prescribes one or more thyroid tests, when he is struggling with an individual who complains and exhibits the classic symptoms of a thyroid gland disease.

The table below shows the symptoms of the aforementioned thyroid diseases, in order to inform readers of the clinical reasons behind the use of thyroid tests.

Thyroid disease	Symptoms and signs
Hyperthyroidism	Decreased body weight, despite an increase in appetite and food consumed Excessive sweating, warm and velvety skin, and high temperature intolerance Increased heart rate, arrhythmias, palpitations, hypertension and left ventricular hypertrophy Anxiety, nervousness, restlessness, mental fatigue and insomnia Shortness of breath, fatigue (muscle weakness), increased respiratory rate and hand tremors Protruding, swollen and red eyes, eye pain, sensitivity to light, double vision and reduction of ocular motility (Graves ophthalmopathy) Brittle, fine and thin hair Fall in fertility and sexual desire Menstrual cycle abnormalities (reduced or absent flows), in women, and gynecomastia, in men Diarrhea Goiter
Hypothyroidism	In the human being young and very young: Extremely slow growth rate Dwarfism (or pituitary dwarfism) Mental retardation (so-called cretinism) Reduced sexual development In the adult human being: Dry skin and thin and thin hair Physical fatigue and chronic muscle weakness Narrow eyelids and rhymes, scarce eyebrows, half-open mouth and swollen tongue (" mixed- facial facies ") Cold skin and intolerance at low temperatures Drowsiness, lethargy, depression and slowing of ideational processes Constipation, increased body weight, swelling of the face, pallor, anemia, hoarseness and lowering of the tone of the voice Memory deficit Decreased hearing Abundant menstrual fluxes (menorrhagia) Muscle cramps, joint stiffness and joint swelling Bradycardia (reduced heart rate), decreased contractile strength of the heart and vasoconstriction Increased levels of low-density lipoprotein (LDL) and serum triglycerides
Goiter	Dysphagia (difficulty swallowing) Dyspnea (difficulty breathing) Dysphonia (difficulty in making sounds) Headache Exophthalmos (pathological protrusion of the eyeballs)
Basedow's disease	Symptoms of hyperthyroidism combined with goiter disorders. A typical disorder is the Graves ophthalmology.
Thyroid nodules	In most cases: Absence of symptoms. Rarely: Discomfort or pain in the neck Enlarged thyroid Difficulty swallowing Hoarseness Breathing problems Alteration of thyroid hormonal activity (hyperthyroidism or hypothyroidism)
Thyroid cancer	In the initial phase: Absence of symptoms In advanced stage: Enlargement of laterocervical lymph nodes; Hoarseness and enlarged thyroid Presence of a small swelling, hard and not very mobile (it is the malignant tumor) Alterations of the voice Symptoms of hypothyroidism
thyroiditis	In the initial phase: Symptoms of hypothyroidism At an advanced stage Symptoms of hyperthyroidism

Risks and complications

Among the thyroid tests, there are some that are absolutely risk-free and others that, instead, due to a certain invasiveness, can give rise to some unpleasant complications.

For example, blood quantification of T3, T4 and TSH levels is a safe and minimally invasive test; thyroid scintigraphy, on the other hand, is a method that presents the risks of using the radiopharmaceutical (which is radioactive and can trigger an allergic reaction).

Contraindications

The presence of contraindications depends on the type of thyroid examination: there are thyroid examinations contraindicated in certain circumstances and thyroid examinations exempt from any type of contraindication.

Considering again the quantification of the blood levels of T3, T4 and TSH, and thyroid scintigraphy, the first diagnostic examination does not present any contraindication, while the second is contraindicated in case of pregnancy, lactation and allergy to certain contrast media.

deepening

This chapter is dedicated to the main features of the aforementioned thyroid examinations.

Visual examination and palpatory examination of the thyroid

The visual examination and palpatory examination of the thyroid are the first two diagnostic evaluations that doctors put into practice, whenever they suspect a thyroid disease.

In other words, they are the tests with which the diagnosis of any thyroid disease begins.

If the visual examination does not need particular descriptions (it is based on the simple observation of the thyroid), the palpatory examination deserves some more attention: in performing it, the doctor palpates the neck (clearly where the thyroid resides) in different ways and from different positions (from front and back), all in order to identify any abnormalities affecting the thyroid gland such as, for example, nodules and / or swelling.

Interesting features:

No invasiveness;
Risk of null complication.

Quantification of blood levels of hormones T3, T4 and TSH

Quantification of blood levels of hormones T3, T4 and TSH is a laboratory test, which follows a blood test . In fact, therefore, it is a simple blood test.

Knowledge of the blood levels of T3, T4 and TSH is essential to establish the presence of important conditions such as hyperthyroidism and hypothyroidism.

Going into more detail:

The presence of hyperthyroidism coincides with high blood levels of T3 and T4, and low blood levels of the pituitary hormone TSH;
The presence of hypothyroidism, on the other hand, coincides with low blood levels of T3 and T4, and high levels of TSH.

Interesting features:

Minimum invasiveness;
Blood withdrawal can cause slight pain and, in the hours following its execution, the development of a hematoma, which disappears within 1-2 days;
Great reliability.

Why is it important to also measure TSH, which is a pituitary hormone?

As mentioned in the initial premise, the production of T3 and T4 by the thyroid also depends on the activity of the pituitary gland, in particular on the presence of the pituitary hormone TSH.

In people with hypothyroidism, high blood levels of TSH are explained by the pituitary's attempt to stimulate the thyroid to produce T3 and T4 (because these are quantitatively small); in people with hyperthyroidism, on the other hand, the low blood levels of TSH are justified in the hypophysis's attempt to turn off the thyroid production of T3 and T4 (because these are huge in terms of quantity).

Despite what some might believe, the TSH measurement is a more sensitive test than the T3 and T4 measurements; moreover, it allows to identify early a functional deficiency of the thyroid and to better plan therapies for diseases such as hypothyroidism or hyperthyroidism.

Thyroid ultrasound

Thyroid ultrasound is an instrumental diagnostic test which, through the use of an ultrasound probe (the so-called transducer), provides fairly detailed images of the thyroid and any anatomical anomalies against it.

Thyroid ultrasound is a very important exam for the research and study of thyroid nodules and malignant thyroid cancer; of these anomalies, thyroid ultrasound makes it possible to identify features such as position, size and consistency.

Interesting features:

Invasivity null (unlike X-rays, ultrasounds are completely harmless);
Quick and inexpensive exam;
Great reliability.

Test for thyroid autoantibodies

Thyroid autoantibodies (or thyroid antibodies ) are abnormal antibodies, produced by the human immune system by mistake, which have the peculiarity of acting specifically against the thyroid or against fundamental elements of thyroid function. This clearly has consequences; in fact, it can result in serious pathological conditions, such as inflammation of the thyroid, damage to the thyroid tissues or dysfunction of the thyroid gland.

The pathological conditions of the thyroid that derive from the presence of thyroid autoantibodies take the name of autoimmune thyroid diseases (to understand what an autoimmune disease is see the article present here). The most classic example of autoimmune thyroid disease is the aforementioned Hashimoto's thyroiditis.

In the aforementioned context, the thyroid autoantibody test is the test by which doctors verify the presence, in an individual's blood, of thyroid autoantibodies.

Without going into too much detail, there are different types of thyroid autoantibodies (thyroglobulin autoantibodies, thyroid peroxidase autoantibodies, etc.); the type of thyroid autoantibody present is important for diagnostic purposes, because it allows to establish with precision which autoimmune thyroid disease is underway.

Since the thyroid autoantibody test is an evaluation performed on a blood sample, a blood sample is required for its realization.

Interesting features:

Minimum invasiveness;
Blood withdrawal can cause slight pain and, in the hours following its execution, the development of a hematoma, which disappears within 1-2 days;
Reliability.

Thyroid scintigraphy

Thyroid scintigraphy is a diagnostic examination of nuclear medicine, which allows to study in detail the anatomy and function of the thyroid, detecting any anomalies. Thyroid scintigraphy involves the use of a radiopharmaceutical (which the nuclear physician injects into the patient during the procedure) and the use of a device called gamma-camera (which serves to translate into images the way in which the radiopharmaceutical is distributed at the level thyroid).

Thyroid scintigraphy is a useful test for the diagnosis and study of various thyroid diseases, including Graves' disease, particular conditions of goiter, thyroid nodules, thyroid cancer and certain forms of hypo- and hyper-thyroidism.

Interesting features:

Moderately invasive due to the use of the radiopharmaceutical (radioactive substance);
Great reliability.

Needle biopsy of the thyroid

The needle biopsy of the thyroid (or thyroid biopsy ) consists in taking a sample of thyroid cells, using a special needle, and in the subsequent analysis of this cell sample in the laboratory.

Performed on thyroid tumors, thyroid needle biopsy is, among thyroid tests, the most indicated to establish the exact nature (malignant or benign) of the tumor mass.

Interesting features: