Thyroid Hypothyroidism - Clinical Manifestations

The Clinical Consequences of thyroid endocrine deficiency are summarized below.Hypothermia is typical, and the patient might complain of cold intolerance. The reduced basal metabolic rate leads to weight obtain despite decreased food intake.

Thyroid hormones are required for regular development of the nervous system. In hypothyroid infants, synapses develop abnormally, myelination is defective, and psychological retardation occurs. Hypothyroid adults have several reversible neurologic abnormalities, including slowed mentation, forgetfulness, reduced hearing, and ataxia. Some patients have severe psychological symptoms, including reversible dementia or overt psychosis ("myxedema madness").

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The cerebrospinal fluid protein degree is abnormally higher. However, total cerebral blood flow and oxygen consumption are regular. Deep tendon reflexes are sluggish, having a slowed ("hung-up") relaxation phase. Paresthesias are common, frequently triggered by compression neuropathies resulting from accumulation of myxedema (carpal tunnel syndrome and tarsal tunnel syndrome).

Hypothyroidism is associated with muscle weakness, cramps, and stiffness. The serum creatine kinase (CK) level may be elevated. The pathophysiology from the muscle disease in hypothyroidism is poorly understood. Study from the bioenergetic abnormalities in hypothyroid muscle suggests a hormone-dependent, reversible mitochondrial impairment. Alterations in energy metabolism aren't discovered in hyperthyroid muscle.

Sufferers rendered acutely hypothyroid by complete thyroidectomy exhibit a decreased cardiac output, reduced stroke volume, reduced diastolic volume at rest, and increased peripheral resistance. However, the pulmonary capillary wedge stress, right atrial pressure, heart fee, left ventricular ejection fraction, and left ventricular systolic pressure-volume relation (a measure of contractility) aren't significantly different from the euthyroid state.

Thus, in early hypothyroidism, alterations in cardiac overall performance are most likely primarily related to alterations in loading problems and exercise-related heart fee rather than to alterations in myocardial contractility. In chronic hypothyroidism, echocardiography shows bradycardia and features that recommend cardiomyopathy, including elevated thickening from the intraventricular septum and ventricular wall, decreased regional wall motion, and decreased systolic and diastolic global left ventricular function.

These changes might be due to deposition of excessive mucopolysaccharides in the interstitium between myocardial fibers, leading to fiber degeneration, decreased contractility, low cardiac output, cardiac enlargement, and congestive heart failure. Pericardial effusion (with higher protein content material) might lead to findings of decreased electrocardiographic voltage and flattened T waves, but cardiac tamponade is rare.

Hypothyroid sufferers exhibit reduced ventilatory responses to hypercapnia and hypoxia. There is a high incidence of sleep apnea in untreated hypothyroidism; such patients occasionally demonstrate myopathy of upper airway muscles. Weakness from the diaphragm also happens frequently and, when serious, can cause chronic alveolar hypoventilation (CO2 retention). Pleural effusions (with higher protein content) might happen.

In hypothyroidism, the plasma cholesterol and triglyceride levels increase, related to reduced lipoprotein lipase activity and reduced formation of hepatic LDL receptors. In hypothyroid children, bone development is slowed and skeletal maturation (closure of epiphyses) is delayed. Pituitary secretion of growth endocrine might also be depressed because thyroid endocrine is required for its synthesis. Hypothyroid animals demonstrate decreased width of epiphysial development plate and articular cartilage and decreased amount of epiphyseal and metaphyseal trabecular bone.

These alterations are not solely due to lack of pituitary development hormone, because administering exogenous development endocrine doesn't restore normal cartilage morphology or bone remodeling, whereas administering T4 does. If unrecognized, prolonged juvenile hypothyroidism outcomes in a permanent height deficit.

A normochromic, normocytic anemia might happen as a result of reduced erythropoiesis. Alternatively, a moderate macrocytic anemia can happen consequently of decreased absorption of cyanocobalamin (vitamin B12) from the intestine and diminished bone marrow fat burning capacity. Frank megaloblastic anemia suggests coexistent pernicious anemia.

Constipation is common and reflects reduced GI motility. Achlorhydria happens when hypothyroidism is linked with pernicious anemia. Ascitic fluid with higher protein content may accumulate.
The skin color in hypothyroidism is dry and cool. Usually, the skin contains a variety of proteins complexed with polysaccharides, chondroitin sulfuric acid, and hyaluronic acid. In hypothyroidism, these complexes accumulate, promoting sodium and drinking water retention and generating a characteristic diffuse, nonpitting puffiness from the skin color (myxedema).

The patient's face appears puffy, with coarse features. Comparable accumulation of mucopolysaccharides within the larynx might lead to hoarseness. The hair is brittle and lacking in luster, and there's often loss of body hair, especially more than the scalp and lateral eyebrows. If thyroid endocrine is administered, the protein complexes are mobilized, a diuresis ensues, and myxedema resolves.

Carotenemia (manifested as yellow-orange discoloration from the skin color) may occur in hypothyroidism because thyroid hormones are needed for hepatic conversion of carotene to vitamin A. Within the absence of sufficient hormone, carotene accumulates in the bloodstream and skin.

In women, hypothyroidism might lead to menorrhagia from anovulatory cycles. Alternatively, menses might become scanty or disappear secondary to diminished secretion of gonadotropins. Because thyroid endocrine usually has an inhibitory effect on prolactin secretion, hypothyroid patients might exhibit hyperprolactinemia, with galactorrhea and amenorrhea. In males, hypothyroidism may cause infertility and gynecomastia from enhanced release of prolactin.

Hyperprolactinemia occurs simply because TRH stimulates prolactin release. There is decreased renal blood flow along with a reduced glomerular filtration fee. The vasoconstriction may be because of decreased concentrations of plasma ANP. The consequent decreased ability to excrete a drinking water load may trigger hyponatremia. However, the serum creatinine degree is usually normal.

Long-standing serious untreated hypothyroidism might guide to a state known as myxedema coma. Impacted sufferers have typical myxedematous facies and skin color, bradycardia, hypothermia, alveolar hypoventilation, and serious obtundation or coma.

This condition is generally precipitated by an intercurrent illness such as an infection or stroke or by a medication for example a sedative-hypnotic. The mortality rate approaches 100% unless myxedema coma is recognized and treated promptly.

Thyroid Hypothyroidism - Clinical Manifestations

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