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37 Cards in this Set

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At what age does acquired hypothyroidism present?
after 6 months
What is primary hypothyroidism?
a decrease in thyroid hormone secretion caused by a damaged, defective, or absent thyroid gland
IF hypothyroidism isn’t primary, then what is it?
Central (hypothalamic or pituitary)
What does TSH do?
TSH stimulates iodine uptake and synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3).
Incidence of congenital hypothyroidism?
1 in 3,500 to 4,000 newborns
What percentage of congenital hypothyroidism is sporadic?
most; 10-15% inherited
In what ethnic group is congenital hypothyroidism most prevalent?
Hispanic infants.
Acquired hypothyroidism usually occurs in
females with autoimmune disease
What chromosomal abnormalities are associated with hypothyroidism?
Down syndrome and Turner syndrome.
What autoimmune diseases are associated with hypothyroidism?
type 1 (insulin-dependent) diabetes mellitus, alopecia, vitiligo, Addison disease, rheumatoid arthritis, and lupus erythematous in the child or family members
What maternal factors may interfere with thyroid function of the unborn child?
A mother who has autoimmune thyroiditis and AH may produce TSH receptor-blocking antibodies that cross the placenta and cause transient fetal hypothyroidism and CH.
Lack of dietary iodine results in
endemic goiter and hypothyroidism, both CH (cretinism) and AH
Does maternal hypothyroidism in pregnancy cause problems for a fetus?
associated with decreased intellectual performance among affected progeny.
What is the most common cause of acquired hypothyroidism?
autoimmune thyroiditis
8 signs of congenital hypothyroidism in first two weeks?
Prolonged neonatal jaundice; Edema of the eyelids, hands, and feet; Gestation >42 wk; Birthweight >4 kg; Poor feeding; Hypothermia ;Protuberant abdomen; Large anterior and posterior fontanelles
5 signs of congenital hypothyroidism after one month?
Darkened and mottled skin; Stressful, frequent, and labored breathing; Failure to gain weight; poor sucking ability; Decreased stool frequency; Decreased activity and lethargy
6 signs of congenital hypothyroidism after 3 months?
Umbilical hernia; Infrequent and hard stools; Dry skin with carotenemia; Macroglossia; Generalized swelling or myxedema; Hoarse cry
6 signs of congenital hypothyroidism 6 months-3 years?
Deceleration of linear growth; Coarse facial features; Dry skin with carotenemia; Hoarse cry and large tongue; Umbilical hernia; Muscular pseudohypertrophy (enlargement of the arm and leg muscles)
7 signs of congenital hypothyroidism in childhood?
Deceleration of linear growth with or without short stature; Delay in eruption of teeth and in shedding of primary teeth; Muscle weakness and pseudohypertrophy (enlargement of the arm and leg muscles); Infrequent and hard stools; Dry skin with carotenemia; Generalized swelling or myxedema; Precocious sexual development: breast development without sexual hair in girls; enlarged testes without sexual hair in boys
7 signs of congenital hypothyroidism in adolescence?
Delayed onset of puberty; Deceleration of linear growth with or without short stature; Delay in eruption of teeth and in shedding of primary teeth; Infrequent and hard stools; Dry skin with carotenemia; Galactorrhea (girls); Generalized swelling or myxedema
What is the thyroid like in thyroiditis?
firm or hard consistency; surface of the gland may be irregular, having a lumpy or nodular consistency.
What tests diagnose primary hypothyroidism?
elevated TSH for age
What are TSH and FT4 in central hypothyroidism?
Low FT4 and low or normal TSH
Do TSH levels reflect biologic activity?
No, and TSH may be elevated with hypothyroidism if it is less biologically active
If the newborn screen is abnormal, is a confirmatory test necessary?
Yes, but treatment should be initiated before the results of the serum tests are available
How do you test for autoimmune thyroiditis?
thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb), especially with a palpable thyroid glan an characteristics of Hashimoto disease
What is the biologically active hormone?
T3
What enters cell and is converted to T3?
FT4
What can interfere with the bound T4 fraction?
inherited TBG deficiency or excess or abnormal binding proteins; Pregnancy or estrogen therapy increases TBG and total T4 values; Many drugs, especially certain anticonvulsant medications, bind to TBG and compete with T4 for binding sites, causing a low total T4 concentration
What is the difference between analog FT4 tests and direct dialysis of FT4?
Analog tests are calculated fom total T4 and T3 resin uptake (T3RU); most laboratories offer this. Direct dialysis of FT4 is more definitive.
What is the most sensitive test of thyroid gland failure?
Elevated TSH
Low FT4 is diagnostic of
consistent with both central and primary hypothyroidism
With central hypothyroidism, what other abnormalities may be present?
Other pituitary hormones, e.g. growth hormone, gonadotropins, hydrocortisone, prolactin
What can impair thyroxine absorption?
iron and calcium medications, high dietary fiber in food and certain soy-containing infant formulas; estrogen therapy for contraception
What diseases interfere with thyroxine absorption?
diseases of the intestine that cause malabsorption, such as celiac disease and inflammatory bowel disease
What is a normal growth velocity for kids 4 yrs-puberty?
at least 5 cm/yr
How often should kids at high risk of hypothyroidism be screened?
annually