hypOthyroid Flashcards
hashimotos thyroiditis
chronic autoimmune thyroiditis
- assoc with hypothyroidism although may be a transient thyroxicosis in acute phase
10x in women
features of hashimotos thyroiditis
- general hypothyroidism sx
- goitre; firm, non-tender
anti-thyroid peroxidase (anti-TPO)
+ anti-thyroglobuline (anti-Tg)
general symtpoms of hypOthyroidism
weight gain
lethargy
cold intolerance
skin - dry, cold, coarse scalp hair
constipation, menorrhagia
neuro
- decreased deep tendon reflexes
- carpal tunnel syndrome
conditions assoc with Hashimotos
other autoimmune
- coeliac
- type 1 DM
- vitiligo
MALT lymphoma !!
causes of hypothyroidism
hashimotos
subacute thyroiditis (de Quervain’s)
iodine deficiency
post-thyroidectomy/radioiodine tx
drugs
- lithium
- amiodarone
- carbimazole (over tx)
side effects of levothyroxine therapy
- hyperthyroidism - over tx
- worsening angina
- atrial fibrillation
- reduced bone mineral density !!
levothyroxine drug interactions
iron
calcium carbonate
–> absorption of levo is reduced, give at least 4hrs apart
which patients should be started on a lower dose of levothyroxine
patients with cardiac disease
>50s
severe hypothyroidism
when changing thyroxine dose, when should TFTs next be checked
8-12wks later
what happens when women on thyroxine becomes pregnant
increased dose (25-50mcg)
(due to increased demands of pregnancy)
- monitor carefully, aim for low-normal
De Quervains thyroiditis
subacute thyroiditis
- occurs following viral infection
typically presents with hypERthyroidism
- initial brief hyper- phase followed by longer hypo- phase
- tender goitre !!
disease course of subacute thyroiditis (deQuervains)
phase 1 (lasts 3-6 weeks): hyperthyroidism, painful goitre, raised ESR
phase 2 (1-3 weeks): euthyroid
phase 3 (weeks - months): hypothyroidism
phase 4: thyroid structure and function goes back to normal
Subacute (De Quervain’s) thyroiditis investigations
thyroid scintigraphy = globally reduced uptake of iodine-131
Subacute (De Quervain’s) thyroiditis management
usually self limiting
- thyroid pain - NSAIDS/aspirin
severe cases (if hypothyroidism develops) -> steroids
subclinical hypothyroidism
TSH raised but T3/4 normal
significance;
- risk of progressing to over hypothyroidism (higher in men)
- risk increased if thyroid autoantibodies
management of Subclinical hypothyroidism
TSH >10 (+ T3/4 normal)
- offer levothyroxine on 2 separate occasions 3 months apart
TSH 5.5-10
- <65, symptomatic + levels 5.5-10 on 2 occasions 3 months apart –> 6 month trial of levo
- old -> watch+wait
- asymmptomatic -> observe, repeat TFT in 6mth
postpartum thyroiditis phases
- thyrotoxicosis
- hypothyroidism
- normal thyroid function
(high recerrence rate in future pregs)
- anti-TPO antibodies found in 90%
management of postpartum thyroiditis
thyrotoxic phase
- propranolol - for sx control
- NO anti-thyroid drugs
hypothyroid phase
- thyroxine
sick euthyroid syndrome
TSH = low
free T4 = low
common in hospital inpatients
- changes are reversible upon recovery, no tx
TFT finding in someone with poor compliance with thyroxine
TSH = high
free T4 = normal
TSH lags + refelcts longer term low thyroxine levels
what drugs can cause hypothyroidism
lithium
amiodarone
(amiodarone can cause both hypo + hyperthyroidism)
TSH + T4 in secondary hypothyroidism caused by pituitary insufficiency
Low TSH
Low T4
–> also both low is sick euthyroid syndrome although TSH might often be normal
(primary hypothyroidism would have high TSH + low T4)
side effects of levothyroixine
-** reduced bone mineral density**
- worsening of angina
- atrial fibrillation
- hyperthyroidism due to over tx
levothyroxine common drug interaction !!!
iron + calcium carbonate !!!!!
–> abdsorption of levo reduced, must give at least 4hrs apart
