Thyroid and anti thyroid Flashcards
used in pyrotechniques before being used for the tx of hyperthyroidism
PERTECHNATE
PERCHLORATE
inhibits iodide trapping ➡️ hypothyroidism
THIOCYANATE
transport to apical membrane drug
PENDRINLODINE
a clinical manifestation similar to cretinism
patients have dwarfism and mental retardation
Pendrin syndrome
organification inhibition
IODIDES
THIONAMIDES
proteolysis drug
IODIDES
minimal effect of thiodamides
preipheral deiodinization
inhibition of conversion of T4 to T3
PTU>METHIMAZOLE
used for arrhythmia
there is greater risk of hypothyroidism due to inhibition of the conversion of T4 to T3
AMIODARONE
those without ISA including PROPRANOLOL and ACEBUTOLOL act by
inhibition of conversion to T3 and helps in reversal of hyperthyroidism
inhibition of conversion of T4 to T3
iodinated contrast media, steroids
decrease the metabolism by inhibition of thyroid hormone conversion
starvation
illness
trauma
most thyroid hormones are bound to
TBG
thyroid hormones are least bound to
albumin
increased TBG in
estrogen
pregnancy
oral contraceptive
if there is increase in tbg you need to increase the
thyroid hormones
decreased TBG by
androgens
steroids
increased displacement from TBG
SALICYLATES
MEFENAMIC ACID
FUROSEMIDE
inhibits T4 absorption
CHOLESTYRAMINE CHROMIUM PICONILATE COLESTIPOL CIPROFLOXACIN PROTON PUMP INH SURALFATE AL OH FE SULFATE CA CARBONATE COFFEE BRAN SOY
treatment for hypothyroidism
iodine supplementation
thyroid hormones
iodine dose for adults
150’ug per day
- 75 ug used for TH synthesis
iodine children dose
90-120 ug per day
pregnant women iodine
200ug per day
iodine supplementation can either lead to
Wolff chaikoff (hypothyroidism) Jod Basedow (hyperthyroidism)
moa of thyroid hormones
binds with receptors in the nucleus, mitochondria and plasma membranes
large number of thyroid hormone receptors are found in
pituitary liver kidney heart skeletal muscle lungs intestines
affinity of the receptor site for T4 is
low
uses of thyroid hormones
hypothyroidism as a result of RAI therapy and surgery, myxedemam cretinism, excessive administration of anti- thyroid drugs
simple goiter without hyperthyroidism
thyroid preparations
synthetic LEVOTHYROXINE LIOTHYRONINE dessicated thyroid LIOTRIX THYROGLOBULIN I-LEVOTHYROIXINE Na
stable uniformity of contents, low cost, lack of allergenic proteins, easily measurable, long half life
SODIUM LEVOTHYROXINE
T4, Eltroxin, Letter
25,50,100mcg tab
not available
more unstable,3-4 times more potent, shorter half life, higher cost, hard to measure, more AE
LIOTHYRONINE
T3,Cytomel,Tertoxin
20 mcg tab
unstable presence of protein antigenicity, rarely used
dessicated thyroid
used for short term reversal of TSH levels
given during thyroid storm
uniform ratio of T3,T4
LIOTRIX
thyroixine,liothyronine
infant and children mgt of hypo
10-15ug/kg/day
adults mgt hypo
1.7ug/kg/day
myxedema coma dose
50-100 ug/day with 500 ug loading dose
hypo after graves
75-125 ug/day
increased by 25-50ug
older px hypo
12.5-25 per day
⬆️25 ug every 2 weeks
pregnant women hypo
30-50% increase in dose
TSH: 0.5-3.0 mU/L
subclinical hypothyroidism
treat TSH > 10 mU/l
initial tx in graves dse
antithyroid drugs
main tx for graves dse
thyroidectomy
antithyroid drugs
THIAMIDES
IODIDES
RADIOACTIVE IODINE
PROPRANOLOL
acts on iodine organification in the thyroid gland and deiodinase rxn in the cells of other tissues in the body
THIOAMIDES
prep of THIOAMIDES
METHIMAZOLE
PROPYLTHIOURACIL
CARBIMAZOLE
moa of thioamides
inhibit synthesis of thyroid hormones primarily by inhibiting organification of Iodine and coupling of the iodotyrosines
inhibit peripheral conversion of T4 to T3
may have direct effect on the immune by decreasing circulating thyroid stimulating ab and restoration of normal suppressor activity
absorption of thioamides
almost completely absorbed
thioamides peak serum levels attained at
1 hour after admin
serum half life of PTU
1-1.5 hours
serum half life of METHIMAZOLE
5 hours
10 x more potent thioamide
METHIMAZOLE
more strongly protein bound - used in pregnancy
PTU
concentrated in fetal thyroid
METHIMAZOLE
admin of PTU
every 6-8 hours
3-4 x a day
METHIMAZOLE admin
once a day
thioamide slower renal excretion
METHIMAZOLE
Most common ae of thioamides
maculopapular rash
AE of thioamides
maculopapular rash
benign transient leukopenia
agranulocytosis
converted to METHIMAZOLE in vivo
CARBIMAZOLE
methimazole dose
10-29 mg q8-12 hours
titrated to 2.5-10mg
PTU dosing
100-200 mg q6-8 hours
titrated to 25-50 mg
must be titrated every month
assessment of thioamide tx
6-8 weeks (FT4, FT3)
30-50% euthyroid in 18-24 months
not mainstay tx for hyperthyroidism
inhibits iodide organification and proteolysis and peripheral deiodination rxn
IODIDES
iodides can lead to
hyperthyroidism-Jod basedow phenomenone
iodide dose
6mg per day in 2-7 days
iodides in pregnancy
CI
crosses the placenta
iodides in nuclear accidents
inhibits attachment of radioactive iodine in the receptor thus prevention of radioactive absorption to the cell
AE of iodides
iodism acneiform rash similar to bromism swollen salivary glands mucous membrane ulcerations conjunctivitis rhinorrhea drug fever metallic taste bleeding disorders rarely anaphylactoid reactions
given as an adjunct
can alleviate clinical condition without an effect on thyroid hormones
given only to those who respond to thioamide
BETA blockers
moa of beta blockers
acts on adrenergic receptors or iodinase 2 enzyme (converts t4 to t3)
beta blocker on iodinase 2 enzyme
has little effect because it acts on the peripheral iodinase reaction
blockers without ISA
PROPRANOLOL
METOPROLOL
ATENOLOL
most commonly used given 4 times a day
PROPRANOLOL
40-80mcg q6 (160mg/day)
METOPROLOL amt
100 mg q12 twice a day
ATENOLOL amt
100 mg OD once a day
only isotope used in thyrotoxicosis
131 iodine
dose of radioactive iodine
185-555 mbq
PTU should be stopped before radioactive iodine tx
3-4 weeks
METHIMAZOLE, CARBIMAZOLE should be stopped before radioactive iodine tx
3 days only
in 5-10 yrs radioactive iodine leads to
hypothyroidism
after tx of RAI treat px with
antithyroid for 3-6 months
patient tx with RAI should be isolated for
8 days