hyper/hypothyroidism Flashcards
what genes are associated with autoimmune thyroiditis
HLA, CTLA4, PTPN22
what is primary hypothyroidism
low free T3/4 –> raised TSH
what is secondary hypothyroidism
pituitary problem –> low TSH –> low T3/4
what is subclinical hypothyroidism and when do you treat it
high TSH but normal T3/4, treat if pregnant or if TSH>10
what is primary hyperthyroidism
high free T3/4 –> low TSH
what is secondary hyperthyroidism
pit problem –> high TSH –> high T3/4
what is subclinical hyperthyroidism
low TSH and normal T3/4
what is subclinical hyperthyroidism associated with and when do you treat it
osteoporosis and AF, treat if TSH <0.1
what are normal TSH levels
0.4-4
what is the definition of hypothyroidism
any disorder that causes insufficient secretion of thyroid hormones
who is most likely to develop hypothyroidism
older white women
what causes hypothyroidism
low iodine (in developing countries), hasimotos autoimmune thyroiditis (developed), drugs eg lithium/ amiadarone, secondary causes eg hypopituitarism
what causes goitres in hypothyroidism
hashimotos, iodine deficiency, drugs
what causes non-goitrous hypothyroidism
atrophic thyroiditis - common from radiotherapy
1)what is hashimotis thyroiditis, 2)who gets it, 3)what is associated with it and 4)what can precede it
1)gradual autoimmune failure and destruction of thyroid, 2)middle aged women get it, 3)assoc with HLA and other AI diseases, 4)can be preceded by transinet hyperfunction
what antibodies are associated with hashimoto’s thyroiditis
TPO anti-thyroid antibodies, CD8 cells, anti-thyroglobulin
what are symptoms of hypothyroidism
everything slowed down: dry hair, bradycardia, tired, depressed mood, weight gain + decreased appetite, constipation, cold intolerance, non-pitting oedema, slow intellect
what is a sign of extreme hypothyroidism
myxoedema - puffy hands and face
what effect can hypothyroidism have on newborns
cretinism: dwarfism and limited mental function
what TFT’s and other biochem tests are seen in hypothyroidism
TFT: high TSH low T3/4, Biochem: high CK/ LDL/ macryoctosis, antibodies: TPO, anti-thyroblobulin
what is the treatment of hypothyroidism
levothyroxine (T4), start on low dose and work up - increase in pregnancy
what is myxoedema coma and who is likely to get it
v. severe hypothyroidism - elderly women with untreated hypothyroidism
what are symptoms of myxoedema coma
extreme bradycardia and heart block, resp failure, hypoxia, hypercarbia and acidosis
what is hyperthyroidism
overactive thyroid leading to excess thyroid hormones
what is thyrotoxicosis
clinical signs and biochem when excess thyroid hormone present
what are the main causes of hyperthyroidism
excessive stimulation: grave’s, hasitoxicosis, cancer. functional nodules: toxic nodule and toxic multinodular goitre
what can cause thyrotoxicosis without hyperthyroidism
thyroid inflamm, ectopic thyroid tissue
what is Grave’s disease and who gets it and what is a big risk factor
autoimmune disease, young women, smoking risk factor
what antibodies are associated with graves disease
TSH receptor antibody (TRAb)
what is the triad of Grave’s disease
hyperthyroidism + goitre, expo-thalamus, pretibial myxoedema (rash on legs)
what are symptoms of hyperthyroidism
diarrhoea, expo-thalamus, double vision, rapid nail growth, lighter/ infrequent periods, weight loss + appetite gain, heat intolerance + sweaty, nervous, heightened emotions, pretibial myxoedema
how to antithyroid drugs work (ATDs)
inhibit TPO and block thyroid hormone synthesis
what is the first line ATD
carbimazole
why should carbimazole be avoided in pregnancy
can cause aplasia cutis
what is the second line ATD (why is it second)
propylthiouracil (PTU) - less potent
how do PTUs work
stops T4 being converted to T3
what are the side effects of ATDs
allergy, jaundice + hepatic failure, agranulocytosis (rare and can be fatal)
what is the first choice of treatment in graves
radioiodine
when is radioiodine contraindicated for graves and what is a common side effect
contraindicated in pregnancy and high risk of hypothyroidism
what other treatments are used in hyperthyroidism (excluding ATDs and RAI)
beta blockers eg propranolol (not in asthma), surgery if RAI contraindicated
what is a thyroid storm/ crisis and what are common symptoms
severe hyperthyroidism: resp+cardiac collapse, hyperthermia, exaggerated reflexes
how do you treat thyroid storm/ crisis
iodine, glucocorticoids, beta-blockers, fluids
what is DeQuervain thyroiditis
viral cause of subacute thyroiditis
what happens to thyroid hormone levels in DeQuervain thyroiditis
causes hyperthyroid phase followed by hypothyroid phase
what are symptoms and treatment of DeQuervain thyroiditis
tenderness and fever - is self-limiting
