Endocrinology

Question 1

Which form of CAH presents with hypertension, ambiguous genitalia and hypokalaemia?

Answer 1

11-Beta-hydroxylase deficiency

Question 2

What genetic mutation is associated with McCune-Albright syndrome?

Answer 2

GNAS gene mutation - chromosome 20 at 13.3

Question 3

What is the hallmark feature of diabetes insipidus?

Answer 3

Inability to concentrate urine

Question 3

What would happen following a water depreivation test to the plasma and urine osmolality in diabetes insipidus?

Answer 3

Plasma rises
Urine remains dilute

Question 3

What is the first sign of puberty in males?

Answer 3

Testicular volume increase >4ml

Question 3

What is the typical blood profile in pseudohypoparathyroidism?

Answer 3

Low calcium
High phosphate
High PTH

Question 3

What is the typical blood profile in vitamin D deficiency?

Answer 3

Low calcium
Low/Normal phosphate
High ALP

Question 4

What is the typical blood profile in hypoparathyroidism?

Answer 4

Low calcium
High phosphate
Low PTH

Question 4

What typically causes pseudohypoparathyroidism?

Answer 4

Genetic defect in the receptor for PTH

Question 5

What mediates the action of vasopressin?

Answer 5

GPCR

Question 5

How is growth hormone deficiency tested for?

Answer 5

Stimulated hormone test
GH levels tested before and after a glucagon dose
- normal response would be GH increase

Question 5

What is the first catecholamine synthesised from DOPA?

Answer 5

Dopamine

Question 5

Which hormone is most responsible for epiphyseal fusion and cessation of growth?

Answer 5

Oestrogen

Question 5

What are the characteristic hand a face features of pseudohypoparathyroidism type Ia

Answer 5

Short 4th and 5th metacarpals
Rounded face

Question 6

What mutation is associated with X-linked hypophosphataemia?

Answer 6

PHEX gene mutation

Question 6

Which hormone is elevated in PCOS?

Answer 6

Testosterone

Question 6

What are the presenting features of PCOS?

Answer 6

Secondary amenorrhoea
Hirsutism
Obesity
Acne

Question 6

What is the characteristic presentation of X-linked hypophosphataemia?

Answer 6

Low phosphate, normal calcium and mildly high PTH
Bowing of legs
Growth retardation
Dental anomalies

Question 6

What do glucocorticoids do to the secretion of growth hormone?

Answer 6

Inhibits GH secretion by suppression of GHRH expression

Question 7

What tumours are typically associated with MEN type 2?

Answer 7

Adrenal pheochromocytoma
Medullary thyroid cancer
Parathyroid hyperplasia/adenoma - hyperparathyroidism

Question 8

What mutation is associated with MEN2?

Answer 8

RET proto-oncogene

Question 8

How is MEN2 inherited?

Answer 8

AD

Question 9

What causes nephrogenic diabetes insipidus?

Answer 9

Renal tubules resistant to ADH - due to defect of vasopressin-2 receptor or post-receptor defect in aquaporin-2

Question 10

Would sex hormone binding globulin be high or low in PCOS?

Answer 10

Low

Question 10

Which hormones are associated with the posterior pituitary?

Answer 10

Oxytocin ADH

Question 10

Which hormones are associated with the anterior pituitary gland?

Answer 10

ACTH GH Prolactin TSH

Question 10

What are the symptoms of Kallmann syndrome?

Answer 10

Anosmia Obesity Hypogonadotrophic hypogonadism

Question 10

What is the treatment of choice for idiopathic central precocious puberty?

Answer 10

GnRH agonist - creates feedback loop

Question 11

What IPSS result would suggest Cushing's disease?

Answer 11

Ratio >2:1 at baseline or >3:1 after CRH administration

Question 11

What blood results are typically seen in 17-alpha-hydroxylase deficiency?

Answer 11

High deoxycortisol and cortisone Low cortisol, androgen and oestrogen

Question 11

What is the method of inheritance of Kallmann syndrome?

Answer 11

X-linked recessive

Question 11

What is the treatment of Kallmann syndrome?

Answer 11

HCG or testosterone to restore pubertal development

Question 11

Where does ADH (vasopressin) exert it's effects within the nephron?

Answer 11

Collecting ducts - increases water permeability

Question 12

Does a rise in urine osmolality following desmopressin suggest cranial or nephrogenic DI?

Answer 12

Cranial

Question 12

What is the gold standard test for differentiating excessive ACTH secretion from pituitary vs ectopic source?

Answer 12

Inferior petrosal sinus sampling - involves samples before and after CRH given compared to peripheral blood

Question 13

What hepatic side effect can carbimazole cause?

Answer 13

Cholestatic liver injury - pruritus, jaundice, pale stool and dark urine

Question 13

At what level would a defect be in hypogonadotropic hypogonadism?

Answer 13

Hypothalamus or pituitary gland

Question 14

What results would be expected in short and chronic stimulation by GnRH in a hypothalamic cause of hypogonadotropic hypogonadism?

Answer 14

No response to short stimulation Normal response following chronic stimulation

Question 15

What is the best test to perform to diagnose central precocious puberty?

Answer 15

FSH and LH before and after GnRH administration - would expect LH >10 and FSH >7

Question 16

What would you expect with urine output in SIADH?

Answer 16

Small amounts of concentrated urine

Question 17

In which state is the majority of thyroid hormone circulated within the blood?

Answer 17

Bound to thyroxine-binding globulin

Question 18

Which vasoactive agent has the highest affinity towards A1, B1 and B2 receptors?

Answer 18

Epinephrine

Question 19

How does 11-b-hydroxylase deficiency present?

Answer 19

Hypertension Ambiguous genitalia Hypokalaemia Older children present with peripheral precocious puberty

Question 20

How does partial 17-alpha-hydroxylase deficiency present?

Answer 20

Primary amenorrhoea and delayed puberty