Notes by dr. Claudio Italiano,
Whenever the thyroid hormone peripheral availability is higher than the physiological tissue needs, the picture of hyperthyroidism is produced. You all happened to come across a patient who complains of palpitations or diarrhea, which has strange redness in the face, which presents itself with the eyes outside (exophthalmos), as if it were a tragic mask, and that, slimming down an eye, for which, having carried out investigations for the thyroid, his doctor has found the TSH "blocked" and high values of thyroid hormones, FT3 and FT4. Now let's see what it is and what the TSH means "blocked". Moreover, this patient may present a swelling to the anterior region of the neck, said technically "goiter", or, in most cases, not present any of this. (see also thyroid). Here we will say, to make ourselves understood, that TSH is a hormone of the pituitary gland, a gland located at the base of the brain, which stimulates the thyroid in the production of hormone FT3 and FT4. To use an analogy dear to us, let's take the example of a jockey riding a lazy horse and have to whip it all the time because it trots. Now, by analogy, the whip is represented by the TSH and the lazy horse, by a thyroid that does not work properly (hypothyroidism). If, on the other hand, the thyroid is like "a crazy horse" that runs without respite, then the jockey would rather have to brake (for example, treatment with methimazole), rather than using the whip.
Thyroid scintigraphy examination
So a "mad" thyroid, which autonomously secretes its hormones (see below) presents a TSH that freezes, ie that tends to zero, when you do the analysis; because the organism intervenes on the thyroid with negative "feed-back" mechanisms, to stop precisely the production of; such stimulation hormone. The term thyrotoxicosis indicates, in fact, clinical, physiopathological and biochemical pictures; in which there is an excess of thyroid hormones that stimulate the body.
These conditions depend on:
a) from the thyroid itself which increases the production of hormones
b) excessive production of thyroid stimulation hormone or TSH, secreted by
pituitary adenomas.
In particular we have the following thyrotoxicosis:
- associated with thyroid hyperfunction
- high production of TSH
- thyrostimulant factors
- Graves disease
- trophoblastic tumor
- hyper-functional adenoma
- toxic multinodular goiter
- subacute thyroiditis
- ectopic thyroid tissue
- "hamburger" toxics
- ovarian struma
The most common forms of hyperthyroidism are represented by the Widespread Toxic Goo or Graves, Flajani and Basedow, which is characterized by a diffuse goiter, signs of thyrotoxicosis and mucopolysaccharide and cell infiltration with ocular bulbs protrusion and ophthalmopathy. and infiltrative dermopathy. The affection mainly affects the female sex :
and is associated with HLA-B8, Drw3, BW 35
and BW 46 haplotypes. In the same families the increase in incidence seems to be
due to a presumed autoimmune origin, and associated with example to other
autoimmune diseases (whose genesis, that is, depends on a movement of antibodies
against the same structures of your body). The etiopathogenetic mechanism that
determines the increase in volume of the gland (toxic goiter) of M.d.B. seems to
be due to antibodies against the stimulating gland, LATS or long-acting thyroid
stimulator and it would be IgG produced by lymphocytes; ultimately there would
be other immunoglobulins, TBII or TSH-binding inhibitory immunoglobulins and
others that would stimulate thyroid cells in the production of AMPc, for which
stimulation would occur and the immunoglobulins can be defined as "thyroid
stimulating immunoglobulin" or TSI. This may be due to disorders of the
immunosuppressive activity of "T suppressor" lymphocytes. Even more difficult to
understand is the formation of exophthalmos, which seems to depend on the union
of an IgG with the beta subunit of TSH with the formation of an EPS substance,
or exophtamos producing-substance.
The thyroid appears in patients with increased volume, with infiltration of inflammatory cells, lymphocytes, macrophages and plasma cells; presents parenchyma hyperplasia with follicles that appear to be cells of increased height showing cytoplasmic vacuolation and papillary projections. Ophthalmopathy is characterized by retrobulbar accumulation of hydrophilic mucopolysaccharides and lymph-plasma cell infiltrates.
A diffuse, superficially smooth goiter appears, with palpatory findings of thrill and breath noise at the auscultation of the thyroid; there is an excess of thyroid hormones in the circulation, with an increase, therefore, of metabolisms, of oxygen consumption and of thermogenenesis. The hands become hot and humid, there are redness at the base of the neck, attributable to vasomotor lability. The skin appendages show brittle hair that tends to fall, trimming nails (Plummer onicolisi). There is tachycardia (see arrhythmias), increased blood pressure, supraventricular arrhythmias, emotional instability and insomnia, fine muscle tremors, sometimes asthenia and adynamia in patients, creatinuria. The gastrointestinal tract will be involved with diarrhea, discharges of 2-4 per day, hepatomegaly, increase in transaminases and alkaline phosphatase; the skeletal system presents bone resorption of calcium which results in hypercalciuria and hypercalcemia, with osteoporosis of the spine. The haematopoietic system will have an increase in the hematocrit, due to the hyperproduction of erythropoietin. The endocrine system undergoes alterations consisting of an increase in the conversion of cortisol to the less active cortisone and an increase in ACTH, so that the diabetic effect (diabetes) of ACTH (counterinsular hormone) is known, and hyperglycemia will occur; the reproductive system will present alterations that go into the male from impotence and loss of libido to menstrual irregularities in women. It appears exophthalmos, due to the infiltration of mucopolysaccharide material in the retrobulbar space, spastic retraction of the upper eyelid, expansion of the rhyme (sign of Dalrymple), convergence defect (sign of Moebius); all this is expressed in the clinical definition of "tragic facies", which recalls the Greek tragedy and the masks employed!
It is therefore proposed to report the hormonal levels in the norm (of T3 and T4), where the TSH is often "blocked" by negative feed-back, that is reduced to the minimum terms. Therefore, compounds with antithyroid activity of the thioamides group (methimazole and propylthiouracil) will be used at dosages ranging from 300 to 600 mg / day for the former and 20-60 mg / day for the latter. The dosage increases until the therapeutic effects are reached (usually takes 6 months), followed by maintenance at 50-200 mg / day for propiltiouracil, 5-20 for methimazole. period of 12.18 months of treatment can lead to "remissions" of thyrotoxic symptoms, if the treatment is sudden and carefully conducted. Beta-blockers, drugs that reduce the frequency, are also used. Radiation therapy with 131I, gamma-emitting radioisotope, is considered when a reduction of the parenchyma is necessary, through the harmful action of the radioisotope on the cells of t. Surgical therapy has the purpose of intervening where the doctor has failed and / or there have been certain compressive phenomena on the organs adjacent to the t., E.g. the recurrent laryngeal nerve (dysphonia), on the trachea (dyspnoea, recurrent bronchitis, laryngitis, etc.).
One speaks, rather, of toxic adenoma (A.T.) when in the context of t. there is a neoformation (benign tumor) capable of an independent hormone secretion, released by any feed-back regulation. It is a pathology of the female sex, in the 3rd-4th decade of life. The nodule appears to the thyroid scintigraphy as a globular mass of 2-3 cm, highly captante (it is colored with intense colors, yellow, red), while the rest of the gianola, appears "off", ie it does not color at all, and that is why TSH is blocked (the TRH stimulation test is performed) and does not exert a stimulus on the healthy part of the tea; it is a non-painful nodule, easily movable, neither adherent to the cutaneous or deep planes, integral with the t.
The manifestations, therefore, are superimposed to those of the M.d.B., however,
the signs linked to the involvement of the heart predominate, with
tachyarrhythmias, supraventricular arrhythmias and myocardial suffering. Therapy
is surgical and healing is usually complete.
In this case a goiter with multiple nodules develops in patients, with portions,
therefore, of the gland that are hyperfunctioning and released from feed-back
adjustments. The debut, here, is slow and we usually talk about old goiters,
where the t scintigraphic examination. appears to be hyper-activating with
interposed cold areas consisting of cystic nodules (ATTENTION TO THE COLD NODES
!: HIDDEN OFTEN NEOPLASTIC INSIDES!).
Clinical picture. As for the M.d.B. and the A.T. there is a hormonal increase
and, therefore, tachycardia, heart failure, arrhythmias, asthenia, fatigue,
hypermetabolism.
Therapy. Here too it makes use of the treatment with 131I and antithyroid drugs;
surgical thyroidectomy should also be considered if the goiters are bulky and if
some nodules are dysplastic or neoplastic.
Thyroiditis also deserves mention as conditions that can be associated with
hyperthyroidism. These are inflammatory processes that affect the thyroid gland
and, therefore, can cause greater thyroid hormone extraction during the
inflammatory process, and are exchanged for trivial sore throat. They can be
distinguished in:
- bacterial forms (pyogenic thyroiditis, tuberculous thyroiditis)
- virals of De Quervain,
- autoimmune (Hashimoto and Riedel's thyroiditis).
Usually it is macroadenomas with autonomous secretion of TSH, which does not respond to the suppression with the administration of thyroid hormones or to stimulation with TRH. Therefore, these subjects seem affected by Graves' disease, with high levels of free thyroxine, but do not have specific signs (exophthalmos, reddened skin, etc.). Moreover, it is possible to search the hyperproduction of the alpha glycoproteinic subunit of TSH, with a ratio of 1: 1 higher.
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