Endocrinology Flashcards
What age is growth hormone licensed from in the UK?
4 years
Which hormones are produced in a sleep-related fashion?
Growth Hormone
Prolactin
Which hormones are produced in a continuous manner?
Thyroxine
Which hormones are produced in a stress-related manner?
ACTH
Which hormones are produced in a circadian fashion?
Cortisol
What is Mc-Cune Albright syndrome a triad of?
Polyostotic fibrous dysplasia (presents as fractures)
Cafe-au-lait spots
Precocious puberty
What is the mechanism of hyperandrogegism in PCOS?
It is thought that excess LH production stimulates ovarian androgen production and that hyperinsulinaemia up regulates 17-alpha-hydroxylase activity which synthesises androgen precursors
What is the hormone profile in PCOS?
Raised FSH and LH
Raised testosterone/ DHEAS
Low sex hormone binding globulin levels
What are the features of androgen insensitivity syndrome?
Defect in androgen receptor gene
Karyotype - XY
Phenotype - female external genitalia
Mullerian structures - Absent
Breast development due to elevated testosterone which is converted to oestrogen
What are the features of SWYER syndrome?
SRY gene mutation causing absent mullein inhibiting substance (therefore mullein structures are present internally) and low testosterone (therefore streak gonads are formed)
What are the features of persistent mullerian duct syndrome?
Characterised by no MIS function aka persistent mullerian ducts
XY normal male phenotype
Mullerian structures found incidentally
Inguinal hernia and undescended testes
What are the features of 5-alpha-reductase deficiency?
5-alpha-reductase is required for the production of dihydrotestosterone
XY female phenotype at birth
Develop sexual hair and an enlarged penis
No internal mullerian structures
Testes in inguinal canal
What is the investigation of choice for diagnosis of Addisons Disease?
Short SynACTHen test
What is the most common form of CAH?
21-hydroxylase deficiency
What test is used to diagnose the most common form of CAH (21-hydroxylase deficiency)?
17-hydroxyprogesterone
17-OHP is a precursor to 11-deoxycortisol and is elevated
What are the blood findings in Addisons disease?
Low Sodium
High Potassium
Low Cortisol
What is sex hormone binding globulin?
It is the glycoprotein that binds to oestrogen and testosterone
Hence less SHBG means more testosterone/ oestrogen circulating freely
What effect does cortisol have on blood glucose levels?
Cortisol increases blood glucose concentration
What is the genetic mutation in McCunn Albright Syndrome?
GNAS-1 gene mutation
What is the pathway of catecholamine synthesis?
Phenylalanine -> L-tyrosine -> L-DOPA -> Dopamine -> Norepinephrine -> Epinephrine
What is the function of LH?
Responsible for the production of oestrogen
What is the function of FSH?
Responsible for initiating follicular growth
Stimulates and recruits immature follicles in the ovary
What is the function of hCG?
Responsible for the maintenance of the corpus luteum which produces the hormone progesterone during pregnancy
Which electrolyte is required for parathyroid hormone secretion?
Magnesium is required for PTH secretion hence a low magnesium can result in hypoparathyroidism
What is glycogenolysis?
The breakdown of glycogen to glucose
What is the Smogyi effect?
Rebound hyperglycaemia following nocturnal hypoglycaemia
Exogenous insulin administration has what effect on C-peptide?
High insulin levels and low C-peptide levels
What occurs in MEN1 syndrome?
Pancreatic (insulinoma/ gastrinoma)
Parathyroid (hyperparathyroidism)
Pituitary
Mutation in MEN1 gene
What occurs in MEN2 syndrome?
Medullary thyroid cancer
Parathyroid
Phaeochromocytoma
Mutation in RET gene
What is the first line Tx for T2DM?
Metformin
Acts by reducing insulin resistance thereby reducing beta-cell demand and thereby prolonging beta-cell life
What is the pathophysiology of weight loss in T1DM?
The lack of circulating insulin results in the inability of glucose to enter the bodies cells by preventing the translocation of the GLUT4 channel to the cell membrane, which would usually transport glucose into the cell. As a result, the body starts preferentially metabolising adipose tissue and muscle tissue as an alternative source of fuel.
