Endocrinology

• Biguanide example

  metformin
• MOA metformin

  increasing peripheral insulin sensitivity and enhancing hepatic glucose uptake thus lowering blood glucose levels
• Biguanide side effects

  nausea, vomiting, abdominal discomfort, diarrhoea, lactose acidosis
• biguanide contraindications

  severe renal and hepatic impairment, acute conditions which affect kidney function or cause significant risk of hypoxia or dehydration
• Sulfonylurea example

  Gliclazide
• sulfonylueas MOA

  stimulate the pancreatic beta cells, promoting the release of insulin
• sulfonylurea max dose

  320mg daily
• chromaffin cells of the adrenal medulla secrete

  noradrenaline and adrenaline
• the adrenal medulla is innervated by

  splanchnic nerves
• Phaeochromocytomas are derived from

  chromaffin cells
• aldosterone is secreted from

  zona glomerulosa
• glucocorticoids are secreted from

  zona fasiculata
• androgens are secreted from

  zona reticularis
• TFT in hyperthyroidism

  TSH low; T4 high, T3 high
• hypomagnesaemia can cause hypocalcaemia by

  impairing the secretion of PTH and making tissues resistant to its action
• sulfonylureas exert their hypoglycaemic effect by

  inhibiting ATP sensitive potassium channels on the membrane of pancreatic beta cells -> depolarise beta cells; open VGCC -> exocytosis of vesicles containing insulin
• autoantibodies in graves disease

  TSH receptor stimulating antibodies; anti0thyroid peroxidase antibodies
• exogenous insulin administration is characterised by

  high serum insulin levels with low C-peptide levels
• insulin decreases serum potassium through

  stimulation of the Na+/K+ ATPase pump
• octreotide class

  somatostatin analogue
• somatostatin functions

  inhibition of GH secretion from anterior pituitary; suppression of insulin and glucagon secretion from pancreas
• primary polydipsia water deprivation test

  urine osmolality high after fluid deprivation and after desmopressin
• leptin is secreted by

  adipose tissue
• leptin acts on

  satiety centres in the hypothalamus
• ghrelin is produced by

  P/D1 cells lining the fungus of the stomach and epsilon cells of the pancreas
• Leptin stimulates the release of

  MSH and CRH
• low levels of leptin stimulates the release

  neuropeptide Y (NPY)
• PTH regulates serum phosphate levels by

  decreasing the expression of phosphate transporters in the renal proximal tubule (decreases expression of sodium-potassium cotransporters) = increases phosphate excretion
• Hashimoto's thyroiditis polymorphism associations

  HLA-DR3, 4 and 5
• Hashimoto thyroiditis pathological features

  lymphocytic infiltration of the thyroid gland and the formation of germinal centres
• Subacute thyroiditis (De Quervain's) pathological featurs

  Disruption of the thyroid follicles with a patchy inflammatory infiltrate with some follicles containing multinucleate giant cells
• Riedel's thyroiditis pathological feature

  inflammation and sense fibrosis of the thyroid follicles extending to the neck veins, oesophagus and trachea
• multi nodular goitres pathological features

  Nodular enlargement of the thyroid along with colloid filled cystic and hyper cellular regions
• Papillary carcinoma of the thyroid pathology

  solid and cystic thyroid mass with papillary formation and empty appearing nuclei
• main component of colloid in the thyroid gland

  thyroglobulin
• thyroglobulin is essential for the storage of

  iodine
• T3 is formed through the coupling of

  MIT and DIT
• T4 is formed through the coupling of

  two DIT molecules
• thyroglobulin contains ... residues which undergo iodination

  tyrosine
• thyroxin binding globulin is produced by

  the liver