Endocrinology Flashcards
Treatment of acute severe hypercalacemia
- REHYDRATION
- LOOP DIURETICS - to increase calcium excretion (if fluid overloaded because hypercalcemia causes osmotic diuresis)
- IV BISPHOSPHONATES (e.g. zoledronate, takes 3-5 days to work)
- IV CALCITONIN - if aggressive presentation
Visual defect assocaited with pituitary tumour?
Bitemporal hemianopia
(pressure on optic chiasm)
Ocular palsy associated with pituitary tumour?
Oculomotor nerve palsy most common due to location in cavernous sinus (CN III)
Hormones released from the anterior pituitary
TSH
ACTH
LH/FSH
Prolactin
GH
Hormones released from the posterior pituitary
Oxytocin
ADH
Describe the growth axis
Describe te adrenal axis
Describe the gonadal axis
Describe the thyroid axis
Describe the prolactin axis
Types of pituitary tumours
PITUITARY ADENOMA = BENIGN
- Microadenoma <1cm
- Macroadenoma >1cm
- Functioning (secretes hormones)
- non-functioning (not secretory)
Most common functional pituitary adenoma types
Prolactinoma (35%) –> hyperprolactinaemia
GH-secreting (20%) –> acromegaly / gigantism
ACTH-secreting –> cushings disease
Treatment of prolactinoma
Dopamine agonist
- carbergoline
- bromocriptine
Describe the Insulin stress test and what is it used for?
Used to test for ACTH deficiency
Given insulin –> drop in blood glucose
Hypoglycaemia should stimulate ACTH release
No increase in ACTH suggests a deficiency
Decribe the oral glucose tolerance test and what is it used for?
Used to test for GH suppression/acromegaly
Glucose should result in GH impression
No suppression suggests acromegaly (check IGF-1 levels
Describe the synacthen test and what is it used for?
Tests for adrenal insufficiecny
Synacthen = artificial ACTH –> should stimulate adrenal gland to produce cortisol
measure cortisol at baseline, 30 mins, and 60 mins. Cortisol should double every 30 mins
Causes of raised prolactin levels
PITUITARY
- Prolactinoma
- Non-functioning adenoma / other causes of hypopituitarism
HYPOTHALAMUS
- Tumours
SECONDARY
- renal failure
- primary hypothyroidism
- adrenal insufficiency
- PCOS
PHYSIOLOGICAL
- Pregnancy
- Breast stimulation
- stress
MEDICATIONS
- Antipsychotics
- antiemetics
- antihypertensive
- oestrogen
What is the Water deprivation test?
Prevent patient drinking water
ask the patient to empty their bladder
hourly urine and plasma osmolalities
Primary/psychogenic polydipsia: what is it and what would the water deprivation test show?
Primary polydipsia = the patient drinks excessive amounts of water, causing dilution of the serum and urine, leading to low serum osmolality and low urine osmolality.
Following water deprivation, the urine becomes more concentrated, and osmolality rises to >750mOsmol/kg.
This show the kidneys are able to concentrate urine and rules out diabetes incipidus
Nephrogenic vs Cranial Diabetes incipidus
Nephrogenic DI - results from renal insensitivity to anti-diuretic hormone (ADH), preventing the concentration of urine (even if a patient is hypovolaemic)
Cranial DI = insufficient ADH release from posterior pituitary –> inability to concentrate urine even if a patient is hypovolaemic. Low urine osmolality even during water deprivation. BUT kidneys are unaffected - so will respond to desmopressin (synthetic ADH) to produce concentrated urine.
Causes of Nephrogenic DI
Inherited
Metabolic - low potassium, high calcium
Drugs: lithium
CKD
Post-obstructive uropathy
Causes of cranial DI
Idiopathic
Congential (defects in ADH gene)
Tumours - craniopharyngioma, pituitary
Brain trauma
Hypophysectomy (removal of pituitary)
Haemorrhage
Infection
What is Sick euthyroid syndrome?
non-thyroidal illness) it is often said that everything (TSH, thyroxine and T3) is low.
In the majority of cases however the TSH level is within the >normal range (inappropriately normal given the low thyroxine and T3).
Changes are reversible upon recovery from the systemic illness and hence no treatment is usually needed.
How often should insulin-dependent diabetics check their glucose when driving?
every 2 hours
DVLA driving rules for diabetics (group 1 drivers)
They can drive a car as long as they have hypoglycaemic awareness + not >1 episode of hypoglycaemia requiring the assistance within the preceding 12 months and no relevant visual impairment.
If diet controlled alone then no requirement to inform DVLA
Drug used to treat Thyrotoxicosis in pregnancy
propylthiouracil
Drug used to treat Thyrotoxicosis in pregnancy
First trimester: propylthiouracil
After 1st trimester: carbimazole
Most common cause of thyrotoxicosis in pregnancy
Grave’s disease (autoimmune)
Signs of thyroid crisis / storm
fever > 38.5ºC
tachycardia
confusion and agitation
nausea and vomiting
hypertension
heart failure
abnormal liver function test
Management of thyroid crisis
- beta-blockers (IV propranolol)
- anti-thyroid drugs: e.g. methimazole or propylthiouracil
- dexamethasone - e.g. 4mg IV qds - blocks the conversion of T4 to T3
Antibodies associated with Hashimoto’s thyroiditis
- antithyroid peroxidase (anti-TPO) antibodies
- antithyroglobulin antibodies
Lithium affect on thyroid gland
Lithium inhibits the production of thyroid hormones in the thyroid gland and can cause a goitre and hypothyroidism
Amiodarone affect on thyroid gland
interferes with thyroid hormone production and metabolism, usually causing hypothyroidism but it can also cause thyrotoxicosis.
Define primary hypothyroidism
Define secondary hypothyroidism
Two most common causes of hyperthyroidism
- Autoimmune / Graves disease (70%)
- Toxic multinodular goitre (15%)
Signs specific to Graves disease (autoimmune)
- Goitre
- Pre-tibial myxoedema
- Acropachy
- Thyroid eye disease - exophthalmos, lagophthalmos, periorbital oedema
