Thyroid Disorders Flashcards by Jessyka Yard

____a____(endocrine/exocrine) glands release hormones directly into the bloodstream, whereas ___b___ (endocrine/exocrine) glands release chemical substances through ducts, releasing outside the body.

a) endocrine (e.g. hypothalamus, pituitary, thyroid, adrenal, gonads, pancreas, parathyroid)

b) exocrine

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this is the most common thyroid hormone

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what is the function of the thyroid gland in children

critical for normal growth and development

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what is the function of the thyroid gland in adults

controls metabolism (affects lipolysis/lipid synthesis, metabolism of carbs and proteins)
increases expression of beta receptors in heart
increases development of type II muscle fibres (fast twitch fibres)

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this hormone secreted by the thyroid is 4x more potent

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this hormone secreted by the thyroid is the major circulating hormone

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what do the TSH, FT3 & FT4 look like in hypothyroidism

TSH = increased
FT3 = low
FT4 = low
(Low levels of thyroid hormones, TSH increases due to -ve feedback)

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what do the TSH, FT3 & FT4 look like in hyperthyroidism

TSH = decreased
FT3 = increased
FT4 = increased
(thyroid hormones increased, TSH decreased b/c of -ve feedback)

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what do the TSH, FT3 & FT4 look like in subclinical hypothyroidism

TSH = increased
FT3 = normal
FT4 = normal

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what do the TSH, FT3 & FT4 look like in subclinical hyperthyroidism

TSH = decreased
FT3 = normal
FT4 = normal

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what is the best screening test for hyper/hypothyroidism?

TSH

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give examples of high risk patients who should be screened for thyroid disease

females > 45
pregnancy/post-partum
family history
goiter
other autoimmune disease (T1DM)
neck radiation
history of thyroid surgery
psychiatric disease (MDD, mania, bipolar)
medications (lithium, amiodarone)

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what are some signs and symptoms of hypothyroidism

decreased HR
fatigue
weight gain
cold intolerance
dry skin/hair & hair loss
constipation
menorrhagia
poor concentration
increased cholesterol
(hypo => think everything slows down)

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list examples of Primary Hypothyroidism

Hashimoto’s Thyroiditis
Iatrogenic )medications, removal of thyroid)
Congenital
decreased iodine intake (rare)

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synthetic T4 First Line for hypothyroidism
Wait 6-8 weeks before dosage increase b/c long half life therefore drug needs to be at steady state before we can see whether or not dose needs to be increased
Take dose same time every day
Side effects: symptoms are usually due to over-tx thus present as hyperthyroidism; palpitations, increased HR, tremors, anxiety, diarrhea (*may aggravate existing CVD - thus start at low dose)
Pregnancy: will likely need increased dose because increased metabolic demands
Lactation: Compatible
Drug Interactions: Space from cations (multivitamins, calcium, potassium, iron) by 2-4hrs, space from coffee/tea by 1hr, space from meals by 30 mins (TAKE ON EMPTY STOMACH), space from PPI & H2 blocker

Levothyroxine (Synthroid, Eltroxin)

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used for Tx of hypothyroidism
- synthetic T3
Short half life
Side effects: same as synthetic T4, may be worse since T3 is more potent

Liothyronine (Cytomel)

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used for Tx of hypothyroidism
Animal protein derived (risk of allergic reaction)
Side effects: same as synthetic T3 & T4

Desiccated thyroid

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when should the patient start to feel better after being started on levothyroxine for hypothyroidism

~ 2 weeks

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how long after starting tx should TSH/FT4 be monitored in hypothyroidism

6-8 weeks -> FT4 more reliable indicator initially, but in the long run we want normal TSH

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If a patient changes LT4 brands, or gains more than 10 pounds, when should they get their TSH checked

4-6 wks following these changes

what are the signs and symptoms of hyperthyroidism

increased HR
tremor
heat intolerance
weight loss
menstrual changes
increased Ca++ levels
dairrhea
weakness
sweating
(hyper = everyhting speeds up)

ophthalmology:
- dry eyes
- blurry vision
- lid lag

this is a type of hyperthyroidism; most common; is an autoimmune disorder due to Thyroid Receptor Antibodies (TRAbs) which stimulate thyroid growth, hormone release

Grave’s Disease

this is a type of hyperthyroidism; autonomous thyroid nodules that secrete excess thyroid hormone (increased radioactive iodine uptake (RAIU))
tx = RAI or removal of thyroid gland

solitary toxic nodules & toxic Multi Nodular Goiter

this is a type of hyperthyroidism; inflammatory damage to the gland which increases release of hormones.
subacute = develops after a viral syndrome
painless = cause is unknown
tx = self-limiting, beta-blockers for HR, NSAIDs for pain control, steroids for severe cases

thyroiditis painless/subacute

this is a type of hyperthyroidism; life threatening thyrotoxicosis (presents as fever, tachycardia, dehydration, delirium, coma, N/Vm diarrhea). caused by: trauma, surgery, RAI, infection, withdrawal from antithyroid tx

thyroid storm

what may be used to tx thyroid storm

beta blockers - for HR propylthiouracil (PTU) - blocks conversion of T4 to T3 iodine solution - blocks release of hormones (administer after PTU) hydrocortisone - antipyuretic & BP

this medication is second line in thyroid storm and first line in the first trimester of pregnancy in hyperthyroidism - these are the only times we used this drug

propylthiouracil (PTU)

this is used to treat hyperthyroidism; first line in adults and children MOA: inhibits the conversion of T3 to T4 in the thyroid gland Side effects: vasculitis, agranulocytosis, neutropenia, reversible cholestatic jaundice Skin rash, abnormal taste/smell, GI upset Get baseline WBC’s => if have symptoms (fever, sore throat, mouth ulcers) consult Dr and get repeat WBC Pregnancy: category D, but maternal benefit outweighs fetal risk Lactation: compatible but caution advised with high doses Drug interactions: warfarin, TCA’s, digoxin, codeine, paroxetine

Methimazole (Tapazole)

DOC in thyroid storm & first trimester pregnancy MOA: inhibits the conversion of T3 to T4 in the thyroid gland; inhibits peripheral conversion of T4 to T3 Side effects: vasculitis, agranulocytosis, neutropenia, hepatocellular injury (if dark urine, jaundice, light stools, unexplained abdominal pain: stop drug + LFTs done) Skin rash, GI upset Get baseline WBC’s => if have symptoms (fever, sore throat, mouth ulcers) consult Dr and get repeat WBC If jaundice, dark urine, light stools, unexplained abdominal pain: STOP DRUG & get LFTs done Pregnancy: category D, but maternal benefit outweighs fetal risk (PTU = DOC for first trimester, then switch to MMI) Lactation: compatible but caution advised with high doses

Prophylthiouracil (PTU)

this class of medication can be used to treat symptoms of hyperthyroidism such as palpitations, anxiety, tremor, heat intolerance

beta-blockers

this treatment for hyperthyroidism will destroy the thyroid. contraindications include pregnancy/lactaiton => defer 6 months before and after

radioactive iodine (RAI)

this form of treatment for hyperthyroidism may be used if drug failure, large thyroid, nodules or severe eye disease

surgery

when should a patient with hyperthyroidism start to feel better after starting tx

3-4 weeks

how long after staring tx should TSH/FT3/FT4 be monitored in hyperthyroidism

q 4-6 weeks until stable

this is the state of having normal thyroid function

euthyroid

how long of a patient being euthyroid do you decrease the dose of MMI/PTU

4-12 weeks euthyroid

once a patient is euthyroid and a stable dose of MMI/PTU is found, how often should TSH be monitored

q 3 months

patients are often treated until euthyroid for _____

1 year

this medication causes hypothyroidism. increased risk if pt has thyroid disease or family history, goitre or thyroid abs. if increased risk monitor TSH q 1 month x 3 months, then q 3 months x 4-8 then q 6-12 months

amiodarone

what are some risks to the mother and fetus if hypo/hyperthyroidism is not treated

maternal: miscarriage, preterm labor, pre-ecamlpsia fetus: stillbirth, low birth weight, delays in mental/motor development

how is hypothyroidism treated in pregnancy

patients typically advised to increased levothyroxine dose by 2 extra tablets per week immediately after pos pregnancy test

when should TSH/FT4 be monitored for hypothyroidism in pregnancy

check when pregnant and q 4 weeks

how is hyperthyroidism treated in pregnancy

mild hyperthyroidism - monitor w/o tx (as long as mom and fetus are asymptomatic) pt may consider radioactive iodine ablation or thyroidectomy for tx of hyperthyroidism over 6 months prior to actively trying to conceive PTU is DOC in first trimester; consider switch to MMI in 2nd and 3rd trimester

when should TSH/FT3/FT4 be measured in hyperthyroidism in pregnancy

q 6 to 8 weeks

when should a TRAb titre be done in pregnancy patients with hyperthyroidism

done at 18-22 weeks - if positive repeat at 34 weeks

what does it mean if TRAb titre is high in pregnant patients with hyperthyroidism

means increased risk of hyperthyroidism for the newborn; neonatologist monitoring rec

what does it mean if TRAb titre is low in pregnant patients with hyperthyroidism

risk to the fetus is low

what is the recommended tx for subclinical hypo/hyperthyroidism

treat if pt is symptomatic - don't treat lab value if pt is not symptomatic