Hypothyroidism Flashcards
Differential if TSH is low
1) primary hyper thyroidism - Graves
2) Secondary hypothyroidism, Pituitary adenoma
In primary hypothyroidism describe TSH levels and T3,T4 levels
1) TSH is High -
2) T3,T4 are low
chief complaint if patient has primary hypothyroidism
- fatigue
- infrequent, irregular periods
- constipation, excessively dry skin
How to diagnose Hypothyroidism
sTSH BHCG CBC, creatinine, AST fasting glucose FSH - if suspecting menopausal
Don’t use T3 and T4 levels to
screen for hypothyroidism
OR
to monitor and adjust T4 doses in patients with known primary hypothyroidism
If all the lab results were normal in a patient presenting with hypothyroid Sx
then do an abdo./pelvic US
If screening TSH is high then you can order
T4, and anti-thyroid antibodies
2 main Ddx for hypothyroidism
- Hashimoto’s
2. Subacute thyrotoxicosis
2 pathologic features of hashimoto’s
lymphoplasmacytic infiltration
nodular proliferations
Iatrogenic causes of hypothyroidism
- amiodarone
Lithium - Iodine excess or deficiency
thiouracils
Painful subacute thyroiditis can occur when?
following a viral infection
Painless subacute thyroiditis can occur?
post-partum
Subacute thyroiditis is described as
thyrotoxicosis with transient hypothyroidism
becomes euthyroid after
In the thyrotoxic phase of subacute thyroiditis what is the treatment?
- beta blocker for palpitations,nervousness, tremor
- Pain med, NSAID, gluc if severe pain
how much L-thyroxine should you give a 50 kg person?
if cardiac disease present or elderly?
50 kg x 1.5 = ucg
- 75 ucg = 0.075 mg
give a lower dose: 25ug daily, increase by 25ug every 4-6 weeks
how should L-thyroxine be taken?
empty stomach, with water, no food or drink 30-60 mins
no vitamins/minerals within 3-4 hours, no iron, no calcium
Who should be screened for hypothyroidism?
- newborns
- prengnat women
- women over 60
- autoimmne conditions present
when do you treat subclinical hypothyroidism (high TSH, normal T3, T4)
symptoms or signs - high LDL
Pregnant
TSH >10 - risk of overt hypothyroidism, increased risk of CVD disease
what happens to the thyroid gland during pregnancy?
T4 transiently drops, and TSH goes up,
For patients already with hypothyroidism, what do you do during pregnancy?
- ## increase dose 30-50% in first trimester to meet needs of mother
At conception patients should add
2pills/ week to dose
If a patient has secondary hypothyroidism
Follow the T4 level not TSH -
