Clinical Flashcards
Causes of primary ovarian insufficiency (POI)
- Idiopathic
- Turner syndrome
- Premutations for Fragile X
- Autoimmune (may be part of polyglandular syndrome)
- Toxicity to ovaries - chemoTx, RadioTx
Physiological stimulators of GH secretion
Hypoglycaemia
Fasting
Starvation
Exercise
Stress and trauma
Sepsis
Insulin
GH secretion is inhibited by..
Hyperglycaemia
Increase in free fatty acids in blood
Hereditary causes of methaemoglobinaemia?
HbM
Cytochrome b5 reductase deficiency
G6PD deficiency (however minor role compared to cytochrome b5 reductase)
Acquired causes of methaemoglobinaemia?
Medications e.g. Benzocaine; dapsone; primaquine
Chemical agents e.g. chlorobenzene; silver nitrate
Nitrate containing foods
What clinical signs/findings lead to a diagnosis of methaemoglobinaemia?
Cyanosis unresponsive to oxygen
Chocolate coloured blood
Saturation gap of >5% (difference between pulse oximeter and multiwavelength oximeter)
Methods to confirm presence of increased Met-Hb?
Multiwavelength oximeter on blood gas instrument
Evelyn-Malloy test (add cyanide to bind with Met-Hb and amount of absorption elimination is proportional to Met-Hb)
What factors other than GnRH regulate FSH secretion?
- Inhibin - inhibits FSH secretion
- Activin - activates FSH secretion
Causes of decreased IGF-1
- GH deficiency
- Malnutrition
- Liver failure
- Renal failure
- Hypothyroidism
- Poorly controlled DM
- Severe infection
Differentials for neonatal jaundice - predominantly conjugated
- Biliary atresia
- Idiopathic neonatal hepatitis
- Infection: TORCH infections
- TPN
- inherited disorders of bilirubin metabolism (Dubin Johnson; Rotor syndrome)
- other inherited disorders (A1AT def; CF; galactosaemia; tyrosinaemia)
Causes of hypopituitarism
Mass lesions
Pituitary surgery
Pituitary radiation
Drug induced e.g. IFNalpha; immune checkpt inhibitor
Infiltrative lesions e.g. hypophysitis, haemchromatosis
Infarction (Sheehan syndrome)
Apoplexy
Genetic mutations
Empty sella
Typical order of affected hormones with hypopituitarism
- Hypogonadism
- GH deficiency
- ACTH
- Hypothyroidism
- Prolactin - rarely deficient
With what causes of hypopituitarism is ACTH secretion more likely to be affected? (name 2)
Lymphocytic hypophysitis
Immune checkpoint inhibitors
What does MELAS stand for?
Mitochondrial
Encephalomyopathy with
Lactic
Acidosis and
Stroke-like episodes
What does LHON stand for?
Leber
Hereditary
Optic
Neuropathy
What happens to SHBG in TSHoma vs thyroid hormone resistance?
Elevated in TSHoma
Normal in thyroid hormone resistance
What happens to alpha subunit in TSHoma?
Elevated alpha subunit: TSH ratio
Tumours associated with MEN1?
- Parathyroid
- Pituitary adenomas (e.g. prolactin; non-functioning; acromegaly)
- Pancreas (e.g. non functioning; gastrinoma; insulinoma)
What proportion of Familial isolated hyperparathyroidism have MEN1 mutation?
20%
What gene is affected in MEN2?
RET (oncogene)
What gene is affected in Wilsons disease?
ATP7B gene - affects the function of the ATPase2 membrane protein
What does POMC stand for?
Pro-opio-melanocortin
What hormones are produced by the corpus luteum?
Steroids: E2, progesterone
Non steroids: Relaxin, VEGF
What are the criteria for successful cannulation with AVS?
Adrenal vein cortisol/Peripheral vein cortisol
>/=2 at baseline
>/=3 post ACTH stimulation