Thyroid

when your thyroid does not make enough thyroid hormones. when it is severe it's called myxedema.

when the thyroid make a lot of thyroid hormones. when it is the severe it is called a thyroid storm.

the hypothalamus releases a thyroid-releasing hormone (TRH) which then stimulates the pituitary gland to release TSH. The TSH will go to the thyroid to release T3 and T4.

when there are high amounts of T3 and T4, TSH is no longer produced to avoid further increases in those hormones. When there is low amounts of the hormones, there will be high of TSH so that it can stimulate the thyroid to make the thyroid hormones.

it is the largest endocrine gland. it is made of two lobes; an isthmus connects it and is highly vascularized. the laryngeal nerves pass UNDER the thyroid.

it is the inactive form. it is made of 4 iodine atoms and this is the main thyroid hormone that is produced which will then be converted into the active form, T3.

this is the active form. it has 3 iodines. it is made when one iodine atom is removed from T4 by deiodinase enzyme.

this is an inactive form. it does not activate thyroid hormone receptors.

iodide from the blood will enter the thyroid cell by active transport. then, the iodide will be converted to iodine by thyroperoxidase and hydrogen peroxide. then the iodine is going to attach to the tyrosine residue that is on the thyroglobulin that is in the thyroid cell and it would make MIT and DIT which would combine and make T3 and T4.

levothyroxine liothyronine

it is T4 long acting body will convert T4 to T3 can be given orally or IV

this is T3 short acting can be given orally or IV

5'-deiodinase

these are drugs that treat hyperthyroidism. there are two; methimazole and propylthiouracil

• it blocks thyroperoxidase from attaching the iodine to the L-tyrosine part of thyroglobulin, preventing the production of the thyroid hormones. -it blocks 5'-deiodenase from converting T4 to T3

the C2 thioketo and unsubstituted N1

thioketo group

T3 is 1.5 days and T4 is 7 days

weakness, fatigue, tiredness cold intolerance headache loss of taste and smell hoarseness no sweating moderate weight gain muscle aches and pain dyspnea slow speech constipation menorrhagia galactorrhea

goitre bradycardia myxedema heart thin brittle nails and thinning skin pale puffiness in face and eyelids thinning of eyebrows thickening of the tongue hypertension fluid in lungs

there is a problem with the thyroid gland itself- thyroid destruction or thyroid deficiency

there is a problem with the hypothalamus or pituitary gland

hashimito's thyroiditis iodide deficiency congenital hypothyroidism natural goitrogens (turnips, cabbage, rutabagas)

TSH > 10 , an abnormal lipid profile, symptoms of hypothyroidism or who are planning a pregnancy

fatigue impaired memory/brain fog constipation cold intolerance pale, thinning skin, coarse hair

if TSH is normal, no further testing is needed. if TSH is abnormal move onto further testing - fT3 and fT4

first-line treatment for hypothyroidism. Normalizes TSH levels. Adults ~1.6 mcg/kg/day Newborns 10–15 mcg/kg/day Elderly or CAD patients Start low: 12.5 mcg/day, titrate slowly

Adjust dose every 4–6 weeks based on TSH levels. High doses and low TSH in elderly patients are linked to: Increased fracture risk & Potential cardiovascular strain (especially in those with CAD)

It is also called T3. T3 = active thyroid hormone, more potent than T4 but has a short half-life. Acts quickly, but its levels fluctuate more, making it less stable than T4 (levothyroxine).

Short-acting → causes rapid changes in blood levels. TSH levels don’t reflect T3 levels reliably, making monitoring harder. Even slow-release T3 formulations still cause fluctuations, leading to:

Periods of high T3, which may increase the risk of: Atrial fibrillation (AFib) Other cardiovascular side effects

Given during withdrawal of L-T4 to prepare for radioactive iodine (RAI) therapy Used only if recombinant TSH isn’t available or not an option Helps stimulate TSH while keeping symptoms of hypothyroidism minimal

this is when the body's immune response attacks the thyroid gland. can be with or without a goitre. Lab testing to look at is Antithyroglobulin and Thyroid peroxidase antibodies.

severe thyroid hypofunction medical emergency symptoms are: Hypothermia Altered sensorium (ranging from stupor to coma) Hypoglycemia Hyponatremia Carbon dioxide retention Ileus Paranoid psychosis

infertility miscarriage pre-clampsia higher rates of C-section and still births

indicates that the person has an overactive thyroid that is producing too much thyroid hormone (hyperthyroidism). Occasionally, it may result from an abnormality in the pituitary gland, which prevents it from making enough TsH to stimulate the thyroid (secondary hypothyroidism).

the thyroid gland is failing because of a problem that is directly affecting the thyroid (primary hypothyroidism)

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