hipotiroidismo it is a syndrome produced by a diminution of the function of gland thyroid that it causes a deficit of tiroideas hormones and manifold symptoms in all the organism of diverse intensity.
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Etiología of the hipotiroidismo
The causes of the hipotiroidismo are multiple, distinguishing mainly the primary hipotiroidismo of the secondary one.
Also tiroideo hipotiroidismo is called, then its cause must to an insufficiency of the own tioidea gland. It constitutes approximately 95% of all the hipotiroidismos. It can as well attend with goiter or without goiter.
Hipotiroidismo without goiter
Also tiroprivo hipotiroidismo is called. It must to a loss of the tiroideo weave with inadequate tiroidea hormone synthesis in spite of the Maxima stimulation with hormone tirotropa (TSH). The destruction or loss of function of the thyroid can be due to multiple causes like:
- Iatrógeno Hipotiroidismo: It supposes a third of all the cases of hipotiroidismo. The lack of gland thyroid can be by tiroidectomía, like for example the practiced one in thyroid cancer, by ablation radioactive with iodine 131 before one tirotoxicosis or by x-ray of tumors of head and neck.
- Tiroidea Disgenesia: She is one lacks anatomical congenital of tiroideo weave. It can be by agenesia complete or lingual ectópico thyroid. It produces congenital hipotiroidismo.
- Idiopático or primary Hipotiroidismo: Usually it is produced in most of the cases by hipotiroidismo autoinmune because it is often associated with antibodies circulating antitiroideos and in some cases are consequence of the effect of antibodies that block the receiver of the TSH. It can be associated to other upheavals like diabetes mellitus, pernicious anemia, sistémico erythematous lupus, reumtoide arthritis, syndrome of Sögren and hepatitis chronicle. Also it can be associate a suprarrenal insufficiency, paratiroidea or gonadal. It is the call endocrino syndrome to poliglandular. The chronic hipotiroidismo autoinmune is the most frequent cause of primary hipotiroidismo in the developed countries.
- Transitory Hipotiroidismo: A autolimitado usually is hipotiroidismo of spontaneous resolution, associated to subacute tiroiditis, silente, postchildbirth after a phase of hyperfunction.
Hipotiroidismo with goiter
It is a hipotiroidismo that can pronounce with increase of the tiroideo size that it is felt and it is seen. Also it can be due to multiple causes like:
- Dishormonogénesis: It is a hereditary biosintético tiroideas hormone defect, reason why it will cause congenital hipotiroidismo.
- Maternal transmission: The antitiroideos drug administration like carbimazol or metimazol during pregnancy not regulated suitably, they produce hipotiroidismo in the fetus, with increase of the TSH and goiter.
- Environmental iodine deficit: As it happens in regions of the interior of the moved away continents of the sea. It is the most frequent cause of hipotiroidismo and goiter at world-wide level.
- Iatrógeno goiter: The drugs can prevent the hormonal synthesis (tionamidas, amiodarona, lithium, iodine), to alter its absorption (colestiramina, ferrous sulphate) or to increase its degradation metabolic (carbamacepina, rifampicina, fenitoína).
- Tiroiditis de Hashimoto: Autoinmune is a tiroiditis and the most frequent cause of hipotiroidismo with goiter.
- Fenomeno Wolff Chaikoff: The excess of iodine in ready people can cause tiroidea hypofunction when inhibiting the tiroideas hormone organificación and synthesis.
- Infiltrativas diseases: Like amiloidosis, esclerodermia, sarcoidosis, hemocromatosis, leukemia, tiroiditis of Riedel e infections.
Also secondary hipotiroidismo is called. It supposes less of 5% of all the hipotiroidismos. It must to a hormone deficit TSH generally due to hipofisario tumor or hipofisaria necrosis postchildbirth.
Also tertiary hipotiroidismo is called. He is less frequent still and it must to a deficit or inadeacuada secretion of the liberating hipotalámico factor of tirotropina (TRH).
Also quaternary hipotiroidismo is called. It must to peripheral resistance to tiroideas hormones, to circulating antibodies against tiroideas hormones.
- prevalence of the hipotiroidismo it varies according to the geographic place and the populations, admitting itself that between the 1 and 3 % of the general population present/display indications of more or less intense hipotiroidismo, with TSH levels andor tiroiditis autoinmune.
- The prevalence of the congenital hipotiroidismo of one each 5000 new born alive ones.
- The spontaneous hipotiroidismo happens one one each 1000 women year, being more frequent in the woman who in the man in a proportion 1/4.
Síntomatología of the hipotiroidismo
symptoms precocious of the hipotiroidismo in the adult they are inespecíficos and of insidioso beginning. Among them is the lethargy, constipation, the intolerancia to the cold, rigidity and muscular contractura, syndrome of the carpiano tunnel and menorragia.
In the exploration of the face it is where more clinical data are appraised and among them it emphasizes:
- Animia: Filled with paste face is called to him or clown face, due to palpebral tumefacción, waxen pallor in which the enrrojecimiento stands out to malar (chapetas malares), with manifest inexpresiveness, coarse aspect, dolt. When he is exaggerated can that is developed a mixedematoso coma. Also it is necessary to differentiate it from a parkinsoniano syndrome.
- Blefaroptosis: It is the fall of the superior eyelid by paralysis (palpebral ptosis).
- Palpebral or periorbitario Edema, with bags in the inferior eyelids.
- Heavy lips.
- Macroglosia: It can cause the mordedura of the language frequently and cause syndrome of obstructiva apnea of the dream. It is necessary to distinguish it of acromegaly.
- Hoarse voice: Sometimes dull, slow, guttural, deep and rough.
- Alopecia: Usually it is of type android, with fine hair, very dry, estropajoso, unpolished, debilitated.
- Fall of the hair of the tail of the eyebrows: He is due to processes autoinmunes with antibodies against the hair. It is necessary to differentiate it from leprosy.
- Thickened skin: The skin appears almost like orange skin, in that the nasogenianos furrows are marked to much and you fold them.
One exists hypoventilation, due to the diminution of force of the respiratory muscles that causes one respiratory insufficiency of different degrees declared by:
- Diminution of the forced vital capacity in espirometría.
- Atelectasia, that usually they are laminar due to the diminution of the ventilation.
- Pleural spill, secondary also to the hypoventilation.
- Anhídrido retention of carbonic, that it can cause one acidosis respiratory and to lead to a mixedematoso coma.
- Bradicardia with weak tones cardiac. It can not exist in the hipotiroidismo.
- Pericárdico spill that it makes worse the prognosis.
- Arterial hypertension: It appears in 30% of the cases.
- Diminution of the volume of ejection.
- Electrocardiographic upheavals like prolonged space PR, complex QRS of low voltage and can exist blockade to auriculoventricular.
- Insufficiency cardiac: A risk exists of isquémica cardiopathy. In the final phase cardiomegalia with expanded miocardiopatía exists one that can cause the death.
Anorexy exists multiple symptoms omo, in spite of the increase of weight, hipoclorhidia in 50% of the paientes that causes heavy digestions, hipoperistaltismo with constipation and sometimes with quadriplegic ileo and megacolon, meteorismo, sluggish biliary vesicle and ascitis.
An increase exists of urea, creatinina, hiponatremia, hipoalbuminemia, albuminuria, that it leads to oliguria by retention of liquids and edemas. A diminution of the renal sanguineous flow with diminution of the filtration to glomerular and the tubular reabsorción takes place.
- Lethargy: Enlentecimiento of the intellectual function, bradipsiquia, bradilalia, loss of initiative (abulia) and memory (amnesia), somnolencia, apathy. It is necessary to distinguish it of dementia.
- Psychiatric upheavals: Rare times happen and paranoica psychosis or depression is characterized by (mixedematosa madness).
- Migraine: One also takes place by deficit of tiroideas hormones and by enlargement and Turkish chair because it must produce much TSH in cases of primary hipotiroidismo. It is necessary to distinguish it of hipofisario adenoma.
- Diminution and enlentecimiento of the osteotendinosos reflections.
- Neuralgias and parestesias, like the syndrome of the carpiano tunnel by compression of the medium nerve.
- Anosmia and ageusia.
- Comma mixedematosos: In cases of serious hipotiroidismo of long evolution.
It appears rigidity by muscular contracturas, easy fatigue, muscular cramps, hipotonía sometimes muscular generalized that gets worse with the cold, muscular thickening in pantorrilas and arms, relaxation of osteotendinosos reflections.
- The skin appears pale, thickness, parched, escamosa, without sweat, doughy and fry.
- Queratodermia to palmoplantar. Sometimes a carotinémico dye by insufficient carotene metabolism exists.
- Cloasma, that it is a pigmentación and front pómulos like in the pregnant women.
- Heavy nails, fluted, fragile and of slow growth.
- Alopecia, nonsingle of the hairy body but of the rest of the body.
- Mixedema: In serious hipotiroidismos acumulaió of mucopolisacáridos hydrophilic exists one in the fundamental substance of the skin and other weaves, that they are surrounded by water and they produce thickening of the skin, face characteristics and doughy induración of the skin that gives to the patient a generalized edematoso aspect that unlike edema of the insufficiency cardiac does not leave fovea. The hipotiroideos seem obese because there is an increase of weight.
The hipotiroidismo is a frequent cause of sterility.
- In women anovulatorios cycles with hipermenorrea exist, abortions, and in some cases amenorrhoea by hiperprolactinemia associated by increase of TRH.
- In the men it produces impotence, diminution of the líbido one, alterations in espermatogénesis, hidrocele.
In the hipotiroidismo one can exist suprarrenal insufficiency associated which it does not disappear with falicilidad with tiroxina treatment, reason why at the beginning of the treatment of the hipotiroidismo it is necessary to administer corticoids.
Alteration of the metabolism
- A diminution of the power metabolism with the disinución of producció of heat exists.
- Diminution of the basal metabolism.
- Intolerancia to the cold and low basal temperature.
Alterations in the blood analyses
- Anemia: It can be macrocítica by pernicious anemia (12%), microcítica anemia by hipermenorrea in women, or normocítica by insufficiency to medular of chronic disease and diminution of metabolism.
- Hipercolesterolemia: Mainly by the increase of LDL.
- Elevation of CPK, muscular as as much cardiac.
- Dilucional Hiponatremia.
- Increase of transaminasas.
- Tiroideas hormone diminution.
- The TSH is high in the primary and diminished hipotiroidismo in the secondary and tertiary hipotiroidismo.
Treatment of the hipotiroidismo
In the established hipotiroidismo, independent of which it is its cause, one is due to resort to tiroxina. The administration must begin with low doses of 25 to 50 microgramsday in greater people, in order to be raising progressively until reaching the dose of 100-300 micrograms to the day. One is due to begin with dose to lower to avoid the abrupt increase of the cost cardiac that produces the tiroxina and that can lead a myocardium infarct in the greater people.
It must monitorizar the free T4 and the TSH to value the effectiveness of the treatment:
- If high normal T4 and TSH exist a subclinical hipotiroidismo.
- If diminished normal T4 and TSH, a sobresodosis of tiroxina exists.
- If normal normal T4 and TSH, exite a good control of the hipotiroidismo.
- If elevated T4 low and TSH, insufficient dose of tiroxina.
At the beginning of the treatment of the hipotiroidismo it is necessary to associate corticoids to avoid the suprarrenal insuficencia.