Thyroid Flashcards
Thyroid Test Levels
TSH
FT4
Anti-TPOAb/AntiTGAb
TSI (TSHR-SAb)
TSH - Gold Standard
0.5 - 4.5 mIU/L
FT4- 0.7 - 1.9 ng/dL
Anti-TPOAb - Variable / autoimmunie hypothyroid
TSI - undetectable - Confirms Graves
Hypothyroid Causes
T4 concentrations
TSH concentrations
Hashimoto’s thyroiditis
Surgery
Meds (Lithium, RAI, Amiodarone)
Iodine deficiency
Decreased total and free T4
Elevated TSH
MILD (Subclinical) Hypothyroidism
- TSH above upper limit (but <10)
- normal FT4
- no overt s/s
Levothyroxine
Gold-standard for treating hypothyroid
full replacement dose 1.6 mcg/kg/day
**Renal - lower 25-50 mcg decrease
12 week onset
Liothyronine
Synthetic t3, rarely needed. peak and trough = thyrotoxicosis after taking
Armour (animal thyroid)
nonphysiologic ratio, no role in modern therapy
Liotrix
LT4 and T3 combination; nonphysiologic ratio; no role in modern therapy
Use of LT4 and dosage
–general replacement
younger than 65 years w/ overt
> 65
w/ ischemic HD
newborns
Overt thyroid
Asymptomatic but--
Cardiovascular issues
pregnant
\+ TPOAb
25-50 mcg/day and titrate every 6-8 weeks based on TSH
<65 w/ overt –> 1.6-1.8 mcg/kg/day (ideal weight for fattys)
> 75 –> 1 mcg/kg/day [25-50 mcg/day, then titrate]
Heart Disease - 12.5 - 25 mcg/day and titrate
newborn- 10-15 mcg/kg/day
Target TSH w/ treatment
adjustment percent
0.5 - 2.5 mIU/L
adjust 10%-20% if out of range and re-check TSH 6-8 weeks later
Overtreatment and Undertreatment of hypothyroid
overtreatment/suppressed TSH more common
–risk of afib, anxiety, depression, osteoporosis, fx
Thyrotoxicosis / hyperthyroid causes
Graves Disease
Thyroid stimulating antibodies
Meds (Amiodarone)
Elevated total and free T4
Suppressed TSH
Treating subclinical hyperthyroid
TSH < 0.1, Graves, post menopausal, underlying cardiovascular disease
(higher risk of cardio and bone sequelae)
otherwise test q 6 months
Beta-blockers & Hyperthyroid
rapid relief of symptoms r/t Beta-Adrenergic system
- only used until better option
- propranolol and nadolol (nonselective preferred)
do not use in HF or ashma; use B-1 specific if contraindicated (metoprolol, atenolol)
Iodide
time of effect
-uses
contraindication
- t4 levels reduced in 24 hours
- lasts 2-3 weeks
- graves before surgery (7-14 days before) and thyroid storm
C/I - radioactive iodine treatment
s/e - hypersensitivity “iodism” – weight loss, depression, gynecomastic
PTU and MMI (Thionamide) [preference?]
- How they work
- Half life
- uses
- PTU beneft v MMI
- Relapse
S/e
Tx of bad s/e
interfere w/ thyroid hormone synthesis
- longer in MMI (6-9 hours)
- Methimazole (MMI) preferred tx (Radioactive iodine is considered after control with antithyroid drugs)
primary therapy for graves or preparative therapy pre-sx / iodine admin
PTU - inhibits t4 to t3;
MMI- signle daily dose, less hepatotoxic
Relapse common, esp. preggo - have plan in place,
-immunosuppressant, *Agranulocytosis (diff then temp WBC decrease - always within 3 months of therapy; fever, malaise, sore throat, ANC <1000) [sepsis and death]
if agranulo – d/c medicine, start on broad abx and filgastrim
