Thyroid and parathyroid Flashcards
Thyroid gland
2” butterfly shaped gland in the neck that secretes T3 and T4 and regulates the body’s metabolism
T3
active form of thyroid hormone
T4
bound and unbound hormone; becomes unbound and activates T3 when senses needing more thyroid hor in the body
thyroid hormone patho
hypothalamus releases TRH when it senses more thyroid hor is needed, and TRH triggers the anterior pit to release TSH which triggers the thyroid gland to release thyroxine (T4) which is converted into T3
Negative feedback in the thyroid
T4 levels tell the ant pit when there is enough TSH and T3 levels tell the hypo when there is enough T3
Which mineral is necessary in the synthesis of thyroid hor
iodine
Thyroid dysfxn
- common
- primary thr dx most common - occurs at the gland level
- more likely in women
Goiter
- can occur with hypo or hyperT
- enlarged thy gland with or w/o sx of thy dysfxn
- if no sx, goiter is considered nontoxic
Causes of goiter
- excess pit TSH which causes excess stim of thy
- low iodine levels which causes low thyroid prod (compensate w/ inc TSH)
- goitrogens - fluid/meds that inc levels (LITHIUM)
Hypothyroidism
Insufficient T3 and T4
Primary hypo
thyroid does not secrete T3 and T4 (knows the body needs more but can’t make it)
- inc TSH sec
- Hashimoto’s is most common
Secondary hypo
Pit not sec enough TSH causing dec TSH levels
- dysfxn on brain level
Hashimoto’s
autoimmune destruction of the thyroid; have thy rec antibodies incl antithyroglobulin antibody and anti-thryoperoxidase antibody
Risk fx for hypothyroidism
female, over 50, white, pregnant, hx autoimmune dx like Lupus, family, meds like amio, tx for hyperthy
early CM of hypothy
DEC METABOLIC ACTIVITY - cold intolerance, wt gain, fatigue, men def, dec attn, inc chol, cramps, constipation, inc carotene level (yellow)
- nonspecific, poor dx
Later signs of hypo?
Puffy face, hair loss, brittle nails
Late CM of hypo
dec temp, brady, wt gain, dec LOC, thick skin, cardiomegaly, HLD, anemia, yellow, hoarse varcies, dec kidney filtration (drug tox), MYXEDEMA
myxedema
severe undiagnosed cases
- life threatening SE incl coma and loss of brain fxn
- derm chx too
Dx of hypo
inc TSH, dec T3/T4, Hash antibodies (anti-Tg, anti-TPO antibodies)
Hyperthyroidism (thyrotoxicosis)
- excess T3 and T4
Primary hyperT
gland overproduces (Graves)
Secondary hyperT
brain prob; pit oversecretes TSH
Tertiary hyperT
brain prob; hypo oversecretes hypo thyrotropic (TRH)
Most common cause of hyperthy
Graves
Causes of hyperT
toxic goiter, adenoma, excess iodine ingestion, subacute thyroid
Risks for hyperT
family hx, Graves, over 40, women, white, meds (amio), preg, excess iodine intake
Graves
- autoimmune disorder of excess T3 and T4 by thyroid-stimulating antibodies that bind to receptors to tell T4 to turn on T3, glands enlarge, and more
Graves sx
heat sensation, wt loss, nerves, insomnia, glands enlarge and palpable, audible bruit, a-fib, heart fail, myxedema, exophthalmos (bulging eyes), periorbital edema
Hyperthy diagnosis
- test for antithyglobulin, antithy receptor antibodies
- US with color - Doppler with thy gland BP
- radioactive iodine scan and measure iodine uptake (inc with Graves and diffuse over whole gland)
Why does hyperT cause a bruit
inc glandular BF
Why does hyperT cause a fib
increase catcholamine release
CM of hypopara
muscle cramp, irritable, tetany, convulsions, Trousseau, Chvestok, inc phos
Hypopara causes
often trauma or damage from thy surg
Parathyroid gland
- 4 pea size glands nestled w/i thyroid tissue that secrete parathy hor (PTH) when Ca levels are low (also promotes vit D prod by kidney)
HyperT tx
- propylthiouracil
- radioactive iodine tx to suppress activity
- surgery
- levo for life
Thyrotoxic storm
- overwhelming release of thy hor that exerts intense stim of met
- life-threatening crisis often precipitated by surg, trauma, infx
- CAN DIE W/I 48 HOURS
hypopara tx
- replace PTH
- normalize Ca and vit D levels
- is para removed, replacement tx is lifelong
Hyperpara
inc sec of PTH, hyperCa
Hyperpara CM
bone b/d, weak, dec conc, neuropathies, HTN, stones, acidosis, osteopenia, fractures, depression, confusion, subtle cog changes, constipation
Tx for hyperpara
dec Ca levels, diuretics, calcitonin, biphosphonates, vit D or surg (if tumor releasing PTH)
Levothyroxine MOA and indications
Synthetic T4 that converts to T3 in the body; hypothyroidism
Levothyroxine SE and NC
- Hyperthyroid or hypothyroid sx
- half life 7d (need to dose regularly)
- takes 1 month to see results
- drug intx and food - take on empty stomach and 30 min before eating (often pt eat first thing when awaken)
- inc risk of bleeding with Warfarin
- take for life
Propylthiouracil (PTU) MOA and indications
- Blocks thyroid hor synthesis, suppress conversion of T4 to T3
- hyperthyroidism
Propylthiouracil (PTU) NC
- Black box - hepatotox
- can be used in 1st tri with caution (not 2nd or 3rd bc hepatotox tho)