Anterior pituitary disorders

Question 1

Causes of increased prolactin

Answer 1

Stalk compression
hypothalamic injury
prolactinoma, cosecretion with pituitary adenoma
hypothyroid

Question 2

Effects of increased prolactin

Answer 2

amenorrhea
infertility
impotence
galactorrhea

Question 3

Causes of decreased prolactin

Answer 3

pregnancy: progesterone inhibits lactation

Question 4

GH increase cause

Answer 4

tumour (acremegaly, adult)

Question 5

ACTH increase causes

Answer 5

pituitary adenoma
ectopic ACTH tumours
–> Cushing’s disease/syndrome

Addison’s disease will increase ACTH but a decrease in cortisol

Question 6

ACTH decrease reasons

Answer 6

autosomal cortisol secreting tumours –> secondary adrenal insufficiency

Question 7

LH increase reasons

Answer 7

gonadotroph cell adenoma (rare)

Question 8

FSH decrease causes

Answer 8

pituitary failure

–> secondary hypogonadism, infertility

Question 9

TSH increase causes

Answer 9

primary hypothyroidism (TSH > 10)

Question 10

TSH decrease causes

Answer 10

Primary hyperthyroidism (TSH < 0.1)
--> secondary hypothyroidism

Question 11

Usual order of loss of pituitary function

Answer 11

GH
LH
FSH
TSH
ACTH
PRL

Question 12

Causes of hypopituitarism

Answer 12

Vascular: aneurysm, arteriosclerosis
I: sarcoidosis, histiocytosis, AI
N: pituitary carcinoma, craniopharyngioma, pituitary tumour, metastatic carcinoma, pinealoma
Drug-related
Radiation
CV, autoimmune/allergic
Head truma, post-partum pituitary necrosis
ENdocrine: DM, hemoglobinopathies, Fe overload, hypothalamic disease, isolated hormone deficiency
Genetic - familial hypopituitaris

Question 13

Testing GH axis

Answer 13

measure IGF1

stimulation test: insulin-induced hypoglycemia, glucagon + arginine
suppression test: gluose suppression test

Question 14

Testing gonadotropic axis

Answer 14

measure LH FSH testosterone estradiol

stimulation test: GnRH
suppression test: excess LH/FSH extremely rare

Question 15

Testing thyroid axis

Answer 15

TSH, free T4

stimulation test: administer TRH

Question 16

Testing adrenocortical axis

Answer 16

measure ACTH, am cortisol, urine cortisol

Stimulation test: insulin-induced hypoglycemia, ACTH stress test
suppression test: dexamethasone

Question 17

Testing prolactin axis

Answer 17

measure prolactin

stimulation test: TRH

Question 18

Triple bolus test

Answer 18

insulin, TRH, GnRH

Question 19

Clomiphene stimulation test

Answer 19

interrupts negative feedback loop –> stimulates gonadotropin release from pituitary

Question 20

GH secreting tumou frequency

Answer 20

8-10%

Question 21

Prolactinoma frequency

Answer 21

30%, most common

Question 22

Mixed GH-prolactin adenoma frequency

Answer 22

4.5%

Question 23

ACTH-secreting tumour frequency

Answer 23

14%

Question 24

Thyrotroph tumour frequency

Answer 24

rare <1%

Question 25

Gonadotropic tumour freq

Answer 25

rare: 2.5%

Question 26

Granular cell tumour frequency

Answer 26

1-2% of unselected biopsies, most frequent of posterior ptiuitary

Question 27

Craniopharyngioma

Answer 27

sella turcica epithelial tumour disturbance of HPA axis, vision, CSF flow heavily calcified and hard to operate on 3-5% of all intracranial neopaslms

Question 28

Consequences of GH excess

Answer 28

before closure of epiphyseal plate: gigantism after closure of epiphyseal plates: acromegaly - thickened sweat skin, large feet, hands, skull and jaw, cardiomegaly, organomegaly, hypertension, arthritis, carpal tunnel syndrome, paresthesias, fatigue, glucose intolerance may have mass effects of pituitary adenoma

Question 29

Consequences of TSH excess

Answer 29

secreting tumours are rare causes goiter and hyperthyroidism weight loss, nervousness, rapid heartbeat, difficulty sleeping, frequent bowel movements women: amenorrhea

Question 30

Consequences of excess sex hormones

Answer 30

precocious puberty | Initiation of sexual maturation before puberty (8 girls 9 boys)

Question 31

Pituitary mass effect

Answer 31

hypothalamus compress optic chiasma compres normal pituitary tissue compress pituitary stalk - block GnRH, dopamine transport

Question 32

Management of small pituitary tumours

Answer 32

<10 mm and no hormonal hypersecretions - 2-4 mm: no further testing - 5-9 mm: MRI 1-2x over next 2 years, if lesion stable, reduce frequncy

Question 33

Pit tumour pharmacotherapy

Answer 33

Most useful in prolactinomas May use in other tumours as an adjunct to surgery/radiotherapy Options: Dopamine agonists --> prolactinomas, less useful for GH Somatostatin analogue --> acromegaly Pegvisomant (GH receptor blocker) --> acromegaly refractory to octreotide Ketoconazole, metyrapone, mitotane --> cushing's disease

Question 34

Pituitary surgery

Answer 34

for large tumours and other hyperfunctional tumours Transphenoidal : used in 95% cases Indications: 1st line for symptomatic pituitary adenomas used when medical/radiotherapy fails provides prompt relief indictaed in pituitary apoplexy with compressive symptoms

Question 35

Pituitary radiotherapy

Answer 35

reserved for patients with large tumours and/or persistent hormonal hyperfunction despite surgical intervention 2 types: 1)conventional: slow response, 80% success in acromegaly, 50% cushing's - high rate of hypopituitarism and other complications possible 2) gamma knife radiosurgery: stereotactic CT guided cobalt 60 gammar adiation to narrowly focused area success: 70% acromegaly, 70% cushings - lower complication rate, still high for hypopituitarism

Question 36

Acromegaly therapy

Answer 36

1) surger 2) octreotide - shrinks tumour 3) GH receptor antagonist - pegvisomat

Question 37

Prolactinoma therapy

Answer 37

1) dopamine agonist 2) surgery 3) radiation

Question 38

Hypogonadotropic hypogonadism

Answer 38

Low LH and FSH Congenital or acquired Acquired more common

Question 39

Congenital causes of hypogonadotropinism

Answer 39

Idiopathic - most often Familial hypogonadotropic hypogonadism - can be tarnsmitted as X-linked, autosomal recessive, or dominant - mutations in GnRH receptor, LH/FSH mutation, etc

Question 40

Acquired causes of low LH and FSH

Answer 40

1) severe illness, stress, malnutrition, exercise - reversible 2) dopamine antagonists/serotonin agonists --> increased prolactin inhibits GnRH 3) Hyperprolactinemia - as above, or may destroy surrounding gonadotropes 4) Sellar Mass lesions: should be distinguished from prolactinomas 5) hemochromatosis

Question 41

Pituitary investigations

Answer 41

structural imaging --> CT/ MRI (best) Functional evaluation --> PET-FDG MACROadenomas usually nonfunctional MICROadenomas usually functional

Question 42

Complete androgen insensitivity

Answer 42

``` X-linked recessive normal female external genitalia absent vagina/short vagina with blind end testes in abdomen, inguinal canals, or labia majora normal Leydig cells + no spermatogenesis Normal breast development reduced/absent pubic hair normal female psychological development testosterone normal or Increased LH increased increased estrogen ```