hypothyroidism Flashcards
signs and symptoms of hypothyroidism
- fatigue
- weight gain
- constipation
- menstrual irregularities
- depression
- dry skin
- intolerance to cold
- reduced body and scalp hair
which one of the following is not a sign of hypothyroidism
- weight gain
- fatigue
- diarrhoea
- reduced body and scalp hair
- dry skin
- depression
- menstrual irregularities
diarrhoea is a symptom of HYPERthyroidism, constipation is a sign of HYPO
complications of hypothyroidism
- dyslipidaemia
- CHD
- stroke
- neurological and cognitive impairments
- HF
- metabolic syndrome
- impaired fertility
- pregnancy complications - adverse maternal and foetal outcomes
- impaired conc and/or memory
- rare: myxoedema coma
what is myxoedema coma
- rare but life threatening medical emergency
- rare complication of hypothyroidism
- severe hypothyroidism with phsyiological decompensation
- usually occurs in pt with long standing, undiagnosed hypothyroidism
- often precipitated by infected, cerebrovascular disease, HF, trauma, drug therapy etc
- generally pt is severely ill with significant hypothermia and depressed mental status
if current or non thyroidal illness is suspected, should you check TFTs
do not check TFTs during acute illness unless it is felt that symptoms may be due to thyroid dysfunction as acute non-thryodial illness is likely to affect TFTs
what is primary hypothyroidism and what are the classifications
- condition arises from thyroid gland itself rather than pituitary or hypothalamic disorder
- can be overt or subclinical
primary hypothyroidism is more common in…
females
primary hypothyroidism may be caused by
- iodine deficiency
- autoimmune disease e.g. Hashmitos thyroiditis
- radiotherapy
- post ablative therapy or surgery
- drugs e.g. amiodarone, lithium
- transient thyroidiitis
- thyroid infiltrative disorders
what is overt hypothyroidism
TSH above reference
FT4 below reference
what is overt hypothyroidism in pregnancy
based on high TSH using trimester specific reference ranges regardless of FT4 levels
subclinical hypothyroidism
TSH above reference
FT4 and FT3 within reference
what is secondary hypothyroidism
- rare
- caused by pituitary or hypothalamic disorder
- e.g. underactive pituitary gland causes underachieve thyroid
what are the results in secondary hypothyroidism
TSH low, normal, or rarely raised
FT4 is low
a patient presents with loss of lateral eyebrows, coarse dry hair and skin, oedema, fatigue and weight gain. what does this suggest
hypothyroidism
when does the hypothyroid phase of postpartum thyroiditis usually occur and how long does it typically last
hypothyroid phase of PPT usually occurs between 3-8 months (most often at 6 months) postpartum and typically lasts 4-6 months
bloods to take when suspecting hypothyroidism and repeat testing
- check TSH, if high then measure FT4 within same sample
- in non-pregnancy, repeat 3-6 months after initial result to exclude other causes of transiently raised TSH and to confirm diagnosis
when to suspect secondary hypothyroidism
if clinical features are suggestive and TSH levels are inappropriately low (may be normal), and FT4 is also low
consider checking additional bloods if primary hypothyroidism is suspected:
- FBC and B12 to assess for possible associated pernicious anaemia
- HbA1c to assess for associated T1DM
- coeliac serology to assess for coeliac disease if a diagnosis of autoimmune thyroid disease is suspected
- serum lipids to assess for associated dyslipidaemia
how can obesity affect TFTs
obesity can affect HPT axis and serum TSH can become raised in overweight or obese people, which may falsely suggest subclinical hypothyroidism
how can biotin affect hormone assays
biotin can lead to….
- False Low TSH Levels: This may suggest hyperthyroidism
- Altered T3 and T4 Levels: can cause falsely elevated or decreased free T4 and T3 levels, complicating the diagnosis of hyperthyroidism or hypothyroidism.
can a pt with hypothyroidism have a goitre
yes
screening for hypothyroidism in pt taking lithium and amiodarone
screen at baseline and every 6 months
if amiodarone stopped, continue monitoring for a further 12 months
screening for hypothyroidism in pt who have has radio iodine therapy or surgery for hyperhtyroidism
screen 4-8 weeks post treatment, then every 3 months for a year, then yearly
1st line treatment for overt hypothyroidism & aim of treatment & what to do if symptoms persist
- levothyroxine (LT4) monotherapy
- aim to maintain TSH within reference
- if symptoms persist, even after achieving normal TSH levels, consider adjusting the dose to achieve optimal well-being whilst avoiding doses that cause TSH suppression or thyrotoxicosis
for patients whose TSH levels were very high before starting treatment or who have had prolonged period of untreated disease, how long can TSH take to return to reference
up to 6 months of treatment with levothyroxine
how often should you consider monitoring TSH levels after initiation of levothyroxine treatment
every 3 months after initiation until stable level, then yearly
which patients should you consider also monitoring FT4 in (in additional to TSH in pt taking levothyroxine for overt hypothyroidism)
consider also monitoring ft4 in pt who continue to be symptomatic
is the use of natural thyroid extract recommended and why
not recommended due to uncertainty around the long term adverse effects and insufficient evidence of benefit over levothyroxine
discuss use of liothyronine monotherapy or combination with levothyroxine for pt with overt hypothyroidism
not recommend due to uncertainty around the long term adverse effects and insufficient evidence of benefit over levothyroxine
how often to check TSH levels once pt is stable on levothyroxine for overt hypothyroidism
annually