Endocrinology Flashcards
Raised PTH leads to:
increased bone resorption -> increased Ca and phos
Increased Ca reabsorption from kidney
increase in active vit D production in kidneys
factors that increase GH secretion
stress
exercise
hypoglycaemia
Glucagon
incidentaloma f/u
check if functioning
if not and >1cm repeat MRI in6mo-1yr
negative feedback on GH
glucose
somatostatin
obesity
Bests creening test for acromegaly
IGF1
Most common cause of acromegaly
98% GH producing pit tumour
most >1cm
Treatment for acromegaly
surgery 1st line (50% cure rate with macroadenomas)
if not cured -> medical therapy (octreotide, lanreotide or pasireotide binding to SST2) rarely dopamine antagonists
if not succesful -> Rdx
Pasireotide causes new onset DM in 60% (also binds to SST5 on beta islet cells)
Mortality in acromegaly
CVD in uncontrolled
Most common cause of GH deficiency
pituitary tumour 50%
First line treatment for prolactinoma
cabergoline (dopamine agonists)
- side effects: valvular heart disease, impuse control
surgery if doesn’t respond
How does TBG (thyroid binding globulin) levels effect T4 levels
Free T4 the same
total T4 increased or decreased
conditions which can effect TBG levels
Increased TBG -> OCP, preganacy , acute hepatitis
decreased TBG -> testosterone tx, steriods, anything which reduced general protein amounts
MOst common cause of thyrotoxicosis
grave’s disease
HLA with highest risk for Graves
HLA DR3
Graves disease pathogenesis important surface markers
T cells present antigen to B cells
uses CD 40 to CD 154 (can be targeted by Iscalimab) -> inhibits autoreactive B cell activation
works in 50%
Antibody markers for graves disease
TSH receptor antibodies
if they are negative can do scinti scan -> diffuse uptake over whole gland
Treatment of graves
carbimazole 12-15mo (50% remission rate)
if relapse or dont go into remission -> radioactive iodine or thyroidectomy
Side effects of carbimazole
most common rash and arthralgias
agranulocytosis (if repeat infections need CBE)
PTU -> hepatotoxicity, ANCA vasculitis
Antithyroid medication in pregnancy
PTU in 1st trimester (carbimazole can cause issues)
Antithyroid treatment in thyroid storm
PTU -> slows down thyroid hormone production and reduces peripheral conversion
Risk factors for graves orbitopathy
smoking
radioiodine
letting pt become hypothyroid
Treatment of severe graves orbitopathy
IV methylpred
can add cyclosporin, rituximab, RTx
tocilizumab
teprotumumab (anti-IGF1)
if still unresponsive -> surgery
Treatment of choice in toxic multinodular goitre
radioactive iodine
Not likely to leave hypothyroid due to only targeting goitres
Symptoms of hyperthyroidism next step
if TSH receptors negative
do scinti scan -> diffuse uptake graves
if no uptake -> thyroiditis
Thyroiditis ab
TPO ab
How to tell between T1 and T2 amiodarone
T1 - increased vascularisation on doppler
T2 - reduced
Hasimoto’s ab
TPO antibodies
Half life of thyroxine
7 days
What to do with thyroxine dose when pregnant
incease by 30%
(HCG can bind to TSh receptor and increase thyroid hormone and reduce TSH)
Most common thyroid ca
pappilary
arises from follicular cells
Next most common follicular
Monitoring ab in thyroid cancer
thyroglobulin
Most comon cause of adrenal insuffiency in developed and developing
developed - autoimmune adrenalitis
developing -> TB
Risks and mechanism of autoimmune adrenalitis
DR3 and DQ2 and DR4 and DQ8 give 30x risk
CD8 T cells and CD4 t cells react against 21-hydroxylase
autoimmune polyendocrine syndrome 1
only in 15%
adrenal insufficency
hypoparathryroidism
chronic mucocutaenous candidiasis
AIRE gene mutation
autoimmune polyendocrine syndrome 2
85%
adrenal insuffiency
autoimmune thyroid
T1DM
Diagnosis of adrenal insuffiency
Synacthen test abnormal <400
ACTH very high
aldosterone low, renin raise
DHEA low
21 hydroxase ab +ve
Most comon enzyme deficiency in congential adrenal hyperplasia
21-hydroxylase
Most common causes of mineralocorticoid excess
60% bilateral adrenal hyperplasia
27% adrenal adenoma
Timing to stop medication when interpreting renin tests
6 weeks for diuretics and spiro
2-4 weeks all others
Drugs that increase renin
ACEi
Diuretics
DHP CCB
drugs that decrease renin
beta blockers
Treatment for bilateral adrenal hyperplasia
Spironolactone, aim normal renin
Most common types of adrenal incidentaloma
non-functioning 75%
of functioning cortisol producing most common
Concerning features for adrenal incidentalomas on imaging
HU >10
Slow washout <60%
>4 cm
How is calcium absorbed in the gut
passive between gap junctions
active through TRP channels
VItamin D function to calcium in gut
increased TRP and Ca APTase synthesis to aid uptake of calcium from gut
Site of most calcium reabsorption in the kidney
proximal tubule
