Endocrinology Flashcards
Which form of CAH presents with hypertension, ambiguous genitalia and hypokalaemia?
11-Beta-hydroxylase deficiency
What genetic mutation is associated with McCune-Albright syndrome?
GNAS gene mutation - chromosome 20 at 13.3
What is the hallmark feature of diabetes insipidus?
Inability to concentrate urine
What would happen following a water depreivation test to the plasma and urine osmolality in diabetes insipidus?
Plasma rises
Urine remains dilute
What is the first sign of puberty in males?
Testicular volume increase >4ml
What is the typical blood profile in pseudohypoparathyroidism?
Low calcium
High phosphate
High PTH
What is the typical blood profile in vitamin D deficiency?
Low calcium
Low/Normal phosphate
High ALP
What is the typical blood profile in hypoparathyroidism?
Low calcium
High phosphate
Low PTH
What typically causes pseudohypoparathyroidism?
Genetic defect in the receptor for PTH
What mediates the action of vasopressin?
GPCR
How is growth hormone deficiency tested for?
Stimulated hormone test
GH levels tested before and after a glucagon dose
- normal response would be GH increase
What is the first catecholamine synthesised from DOPA?
Dopamine
Which hormone is most responsible for epiphyseal fusion and cessation of growth?
Oestrogen
What are the characteristic hand a face features of pseudohypoparathyroidism type Ia
Short 4th and 5th metacarpals
Rounded face
What mutation is associated with X-linked hypophosphataemia?
PHEX gene mutation
Which hormone is elevated in PCOS?
Testosterone
What are the presenting features of PCOS?
Secondary amenorrhoea
Hirsutism
Obesity
Acne
What is the characteristic presentation of X-linked hypophosphataemia?
Low phosphate, normal calcium and mildly high PTH
Bowing of legs
Growth retardation
Dental anomalies
What do glucocorticoids do to the secretion of growth hormone?
Inhibits GH secretion by suppression of GHRH expression
What tumours are typically associated with MEN type 2?
Adrenal pheochromocytoma
Medullary thyroid cancer
Parathyroid hyperplasia/adenoma - hyperparathyroidism
What mutation is associated with MEN2?
RET proto-oncogene
How is MEN2 inherited?
AD
What causes nephrogenic diabetes insipidus?
Renal tubules resistant to ADH - due to defect of vasopressin-2 receptor or post-receptor defect in aquaporin-2
Would sex hormone binding globulin be high or low in PCOS?
Low
Which hormones are associated with the posterior pituitary?
Oxytocin
ADH
Which hormones are associated with the anterior pituitary gland?
ACTH
GH
Prolactin
TSH
What are the symptoms of Kallmann syndrome?
Anosmia
Obesity
Hypogonadotrophic hypogonadism
What is the treatment of choice for idiopathic central precocious puberty?
GnRH agonist - creates feedback loop
What IPSS result would suggest Cushing’s disease?
Ratio >2:1 at baseline or >3:1 after CRH administration
What blood results are typically seen in 17-alpha-hydroxylase deficiency?
High deoxycortisol and cortisone
Low cortisol, androgen and oestrogen
What is the method of inheritance of Kallmann syndrome?
X-linked recessive
What is the treatment of Kallmann syndrome?
HCG or testosterone to restore pubertal development
Where does ADH (vasopressin) exert it’s effects within the nephron?
Collecting ducts - increases water permeability
Does a rise in urine osmolality following desmopressin suggest cranial or nephrogenic DI?
Cranial
What is the gold standard test for differentiating excessive ACTH secretion from pituitary vs ectopic source?
Inferior petrosal sinus sampling - involves samples before and after CRH given compared to peripheral blood
What hepatic side effect can carbimazole cause?
Cholestatic liver injury - pruritus, jaundice, pale stool and dark urine
At what level would a defect be in hypogonadotropic hypogonadism?
Hypothalamus or pituitary gland
What results would be expected in short and chronic stimulation by GnRH in a hypothalamic cause of hypogonadotropic hypogonadism?
No response to short stimulation
Normal response following chronic stimulation
What is the best test to perform to diagnose central precocious puberty?
FSH and LH before and after GnRH administration - would expect LH >10 and FSH >7
What would you expect with urine output in SIADH?
Small amounts of concentrated urine
In which state is the majority of thyroid hormone circulated within the blood?
Bound to thyroxine-binding globulin
Which vasoactive agent has the highest affinity towards A1, B1 and B2 receptors?
Epinephrine
How does 11-b-hydroxylase deficiency present?
Hypertension
Ambiguous genitalia
Hypokalaemia
Older children present with peripheral precocious puberty
How does partial 17-alpha-hydroxylase deficiency present?
Primary amenorrhoea and delayed puberty
