Hypothyroidism (pronounced /ˌhaɪpɵˈθaɪrɔɪdɪzəm/) is a condition leading to the deficiency in the production of thyroid hormone.
Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by any number of other causes such as several conditions of the the thyroid gland, or less commonly, the pituitary gland or hypothalamus. It can result from a lack of a thyroid gland. It can also be due to iodine-131 used to treat thyroid cancer, its surgical removal.
Cretinism is a form of hypothyroidism found in infants. Hypothyroidism is highly underdiagnosed, especially in women, to the tune of 13,000,000 Americans and 200,000,000 people worldwide.
Signs and symptomsEarly hypothyroidism is often asymptomatic and can have very mild symptoms. Subclinical hypothyroidism is a state of normal thyroid hormone levels, thyroxine (T4) and triiodothyronine (T3), with mild elevation of thyrotropin, thyroid-stimulating hormone (TSH). With higher TSH levels and low free T4 levels, symptoms become more readily apparent in clinical (or overt) hypothyroidism.
Poor muscle tone (muscle hypotonia)
Any form of menstrual irregularity and fertility problems
Hyperprolactinemia and galactorrhea
Elevated serum cholesterol
Cold intolerance, increased sensitivity to cold
Muscle cramps and joint pain
Thin, brittle fingernails
Dry, itchy skin
Weight gain and water retention
Bradycardia (low heart rate – fewer than sixty beats per minute)
Slow speech and a hoarse, breaking voice – deepening of the voice can also be noticed, caused by Reinke's Edema.
Dry puffy skin, especially on the face
Thinning of the outer third of the eyebrows (sign of Hertoghe)
Abnormal menstrual cycles
Low basal body temperature
Impaired cognitive function (brain fog) and inattentiveness.
A slow heart rate with ECG changes including low voltage signals. Diminished cardiac output and decreased contractility
Reactive (or post-prandial) hypoglycemia
Anemia caused by impaired haemoglobin synthesis (decreased EPO levels), impaired intestinal iron and folate absorption or
B12 deficiency from pernicious anemia
Shortness of breath with a shallow and slow respiratory pattern
Increased need for sleep
Irritability and mood instability
Yellowing of the skin due to impaired conversion of beta-carotene to vitamin A (carotoderma)
Impaired renal function with decreased glomerular filtration rate
Acute psychosis (myxedema madness) (a rare presentation of hypothyroidism)
Decreased libido in men due to impairment of testicular testosterone synthesis
Decreased sense of taste and smell (anosmia)
Puffy face, hands and feet (late, less common symptoms)