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Hypothyroidism is the disease state in humans and domestic animals caused by insufficient production of thyroid hormone by the thyroid gland. There are several distinct causes for chronic hypothyroidism in human beings, the most common being Hashimoto's thyroiditis (an autoimmune disease) and radioiodine therapy for hyperthyroidism. Historically, iodine deficiency was the most common cause of hypothyroidism world-wide. Secondary hypothyroidism occurs if the pituitary gland is damaged by a tumor, radiation, or surgery so that it is no longer able to instruct the thyroid to make enough hormone^[1]. It is a relatively common disease in purebred domestic dogs as well, and can have a hereditary basis in dogs. Image File history File links Wiki_letter_w. ... The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. ... The thyroid gland and its relations In anatomy, the thyroid (IPA θaɪɹoɪd) is an endocrine gland. ... Hashimotos thyroiditis, the most common form of thyroiditis, is an autoimmune disease where the bodys own antibodies fight the cells of the thyroid. ... Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. ... Radioiodine is the common name for iodine-131, a radioisotope of iodine. ... Hyperthyroidism (or overactive thyroid gland) is the clinical syndrome caused by an excess of circulating free thyroxine (T4) or free triiodothyronine (T3), or both. ... Iodine is an essential trace element; the thyroid hormones thyroxine and triiodotyronine contain iodine. ... The term Dogs, when used by itself can refer to: The plural of dog Dogs, a song by Pink Floyd This is a disambiguation page — a list of articles associated with the same title. ...

The severity of hypothyroidism varies widely. Patients are classified as "subclinical hypothyroid" if diagnostic findings show thyroid hormone abnormalities, but they do not exhibit any symptoms. Others have moderate symptoms that can be mistaken for other diseases and states. Advanced hypothyroidism may cause severe complications, the most serious one of which is myxedema. Myxedema is a skin and tissue disorder usually due to hypothyroidism. ...

Hypothyroidism results from sporadic inheritance, sometimes autosomal recessive. To diagnose the condition, levels of T4 (thyroxine) and TSH (thyroid stimulating hormone) are measured. The disease may also be caused by a lack of thyroid gland or pituitary hormone. Treatment comes in the form of thyroid hormone replacement therapy. The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. ... Thyroid-stimulating hormone (also known as TSH or thyrotropin) is a hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland. ... The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. ...

Signs and symptoms

Hypothyroidism has been called the "great imitator" for the vast number of medical conditions it can mimic. "Thyroid hormones are essential and primary regulators of the body's metabolism. Imbalances can affect virtually every metabolic process in the body, exerting significant effects on mood and energy level. Thyroid function has a profound impact on overall health via its modulation of carbohydrate, protein, and fat metabolism, vitamin utilization, mitochondrial function, digestive process, muscle and nerve activity, blood flow, oxygen utilization, hormone secretion, sexual and reproductive health, and many other physiological parameters" ^[2]. Metabolism (from Greek μεταβολισμός metabolismos) is the biochemical modification of chemical compounds in living organisms and cells. ... ... Digestion is the process whereby a biological entity processes a substance, in order to chemically convert the substance into nutrients. ... Physiology (in Greek physis = nature and logos = word) is the study of the mechanical, physical, and biochemical functions of living organisms. ...

Adults

• Slowed speech and a hoarse, breaking voice. Deepening of the voice can also be noticed.
• Impaired memory
• Impaired cognitive function (brain fog)
• Urticaria (hives)
• Migraine headache
• Increased sensitivity to heat and cold
• A slow heart rate with ECG changes including low voltage signals. Diminished cardiac output and decreased contractility.
• Pericardial effusions may occur.
• Sluggish reflexes
• Dry puffy skin, especially on the face, and hair loss, especially thinning of the outer third of the eyebrows
• Depression (especially in the elderly)
• Weight gain and obesity
• Anemia caused by impaired hemoglobin synthesis (decreased EPO levels), impaired intestinal iron and folate absorption or B12 deficiency from pernicious anemia
• Slowed metabolism
• Constipation
• Fatigue (physical)
• anxiety/panic attacks
• Choking sensation or difficulty swallowing
• Shortness of breath with a shallow and slow respiratory pattern.
• Impaired ventilatory responses to hypercapnia and hypoxia.
• Increased need for sleep
• Muscle cramps and joint pain
• Brittle fingernails
• Osteoporosis
• Paleness
• Irritability
• Yellowing of the skin due to impaired conversion of beta-carotene to vitamin A
• Abnormal menstrual cycles
• Impaired renal function with decreased GFR.
• Thin, fragile or absent cuticles
• Infertility or difficulty becoming pregnant
• Elevated serum cholesterol
• Acute psychosis (myxedema madness) is a rare presentation of hypothyroidism
• Poor muscle tone (muscle hypotonia)

Dysphonia is the medical term for hoarseness or other phonation disorders. ... In psychology, memory is the ability of an organism to store, retain, and subsequently recall information. ... Bradycardia, as applied in adult medicine, is defined as a heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min [1]. It is also less commonly known as brachycardia. ... ECG may also refer to the East Coast Greenway Lead II An Electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical voltage in the heart in the form of a continuous strip graph. ... Pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity. ... The mechanism of the reflex arc A reflex action is an automatic (involuntary) neuromuscular action elicited by a defined stimulus. ... Baldness (formally alopecia) is the state of lacking hair where it usually would grow, especially on the head. ... Clinical depression (also called severe depressive disorder, major depressive disorder) is a state of intense sadness, melancholia or despair that has advanced to the point of being disruptive to an individuals social functioning and/or activities of daily living. ... This article or section should be merged with Birth control pill Weight Gain When Taking The Pill When starting to take the birth contol pill some people may expierence slight weight gain. ... This article discusses the medical condition. ... Erythropoietin Erythropoietin (or EPO) is a glycoprotein hormone that is a growth factor for erythrocyte (red blood cell) precursors in the bone marrow. ... Folic acid (the anion form is called folate) is a B-complex vitamin (once called vitamin M) that is important in preventing neural tube defects (NTDs) in the developing human fetus. ... Pernicious anemia refers to a type of autoimmune anemia. ... Abnormal basal metabolic rate refers to a high or low BMR. Associated conditions (incomplete list) hypothyroidism Hyperthyroidism Diabetes Inborn errors of metabolism Category: ... Constipation or irregularity, is a condition of the digestive system where a person (or animal) experiences hard feces that are difficult to eliminate; it may be extremely painful, and in severe cases (fecal impaction) lead to symptoms of bowel obstruction. ... The word fatigue is used in everyday living to describe a range of afflictions, varying from a general state of lethargy to a specific work induced burning sensation within muscle. ... Anxiety is a complex combination of emotions that includes fear, apprehension and worry, and is often accompanied by physical sensations such as palpitations, nausea, chest pain and/or shortness of breath. ... Choking is the obstruction of the flow of air into a persons lungs by a foreign object, commonly food. ... Dysphagia is the technical term for the symptom of the sensation of difficulty in swallowing. ... Dyspnea (Latin dyspnoea, Greek dyspnoia from dyspnoos - short of breath) or shortness of breath (SOB) is perceived difficulty breathing or pain on breathing. ... Hypercapnia (from the Greek hyper = above and kapnos = smoke) is a condition where there is too much carbon dioxide (CO2) in the body. ... Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ... This article is about muscular pain. ... In medicine, arthralgia (literally: joint pain, from arthros = joint and -algia denoting pain) is the presence of painful joints in the absence of frank arthritis. ... Brittle nails can be due to an infection or a nutritional disorder, but they can also be an indication of several other medical conditions, including Iron deficiency, anemia, and hypothyroidism. ... Osteoporosis is a disease of bone in which the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of non-collagenous proteins in bone is altered. ... Pallor is an abnormal loss of skin or mucous membrane color. ... Irritability is an excessive response to stimuli. ... Carotene is a terpene, an orange photosynthetic pigment, important for photosynthesis. ... Menstrual cycle The menstrual cycle is the set of recurring physiological changes in a females body that are under the control of the reproductive hormone system and necessary for reproduction. ... Glomerular filtration rate (GFR) is the volume of fluid filtered from the renal glomerular capillaries into Bowmans capsule per unit time. ... The eponychium of a pinky, or little finger. ... Infertility is the inability to naturally conceive a child or to carry a pregnancy to full term. ... Infertility is the inability to naturally conceive a child or the inability to carry a pregnancy to term. ... Hypercholesterolemia (literally: high blood cholesterol) is the presence of high levels of cholesterol in the blood. ... Myxedema psychosis, more colloquially known as myxedema madness, is a relatively uncommon consequence of hypothyroidism, particularly Hashimotos thyroiditis. ... Hypotonia is a condition of abnormally low muscle tone (the amount of tension or resistance to movement in a muscle), often involving reduced muscle strength. ...

Hypothyroidism in domestic dogs

Hypothyroidism in dogs is a slowly progressive disease as well and can be difficult to diagnose accurately in the early stages. Dogs with hypothyroidism are plagued by a number of health problems including recurring skin infections and lethargic behavior. Hypothyroidism in dogs may also progress to myxedema coma.

External links

• ATA Hypothyroidism Booklet
• American Thyroid Association
• American Association of Clinical Endocrinologists
• American Foundation of Thyroid Patients
• Thyroid Foundation of America

References

1. ^ ATA Hypothryoidism Booklet, pge 6, American Thyroid Association, 2003.
2. ^ Comprehensive Thyroid Assessment, [Geneva Diagnostics web site article]

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