Hypopituitarism Flashcards
Definition
Decreased secretion of anterior pituitary hormones
Order of affected hormones
Growth hormone FSH/LH PRL TSH ACTH
Cause of pan-hypopituitarism
Irradiation
Surgery
Pituitary tumor
Etiology
Neoplastic: Pituitary adenoma (most common cause) Craniopharyngomas Rathke's cyst Other space occupying->sellar meningiomas, metastases, plasmacytomas, germ cell, astrocytomas Pituitary metastasis
Vascular:
Pituitary apoplexy
Sheehans
Intrasellar aneurysms
Inflammatory/infiltrative: Lymphocytic hypophysitis Immunotherapy Haemachromatosis Sarcoid TB
Infection:
Abscess
Fungal
Tuberculomas
Congenital Radiotherapy Surgery Traumatic brain injury Empty sella syndrome
Classification of microadenoma and macroadenoma
Micro 10mm
How to remember which hormones are lost first
The hormones essential for life (ACTH and TSH) lost last
How does pituitary adenoma lead to hypopituitarism
Impaired blood flow
Compression
Interference of hormone delivery
Presentation
Due to hormone lack and cause presence of risk factors FHx of pituitary hormone deficiencies headaches failure to thrive or short stature infertility hypoglycaemia amenorrhoea/oligomenorrhoea galactorrhoea delayed puberty hypotension visual field defects ophthalmoplegia Other diagnostic factors cardiovascular events cold intolerance weight gain hypoactive sexual desire hot flushes erectile dysfunction and reduced libido nausea vomiting fatigue weakness dizziness constipation nocturia and polyuria breast atrophy reduced bone and muscle mass loss of axillary and pubic hair dry skin delayed relaxation of reflexes
Clinical features based on the hormone deficient
GH->central obesity, atherosclerosis, reduced strength/exercise, cardiac output, hypoglycemia, osteoporosis
FSH/LH: libido loss, oligo/amenorrhea, -ve fertility, ED, hypogonadism
ACTH->adrenal insufficiency, anorexia, wt loss, nausea, myalgias, pallor, hypotension
TSH->hypothyroid
DI-> nocturia, polyuria, polydipsia (suggests hypothalmic/hypothalmic/pituitary stalk cause)
Investigations
serum electrolytes->low sodium (ACTH -ve), +sodium (DI_
8 a.m. cortisol and ACTH->low cortisol and inappropriately low ACTH
TFT
8 a.m. testosterone, FSH, and LH in men
estradiol, FSH, and LH in women
prolactin->slightly elevated
insulin-like growth factor-1 (IGF-1)
cosyntropin/tetracosactide stimulation test
Other test to consider;
Insulin tolerance test
Water deprivation and desmopressive response test
MRI pituitar
What is the cosyntropin stimulation test
250 micrograms of cosyntropin (synthetic ACTH 1-24) is administered intramuscularly or intravenously; serum cortisol levels are measured at 30 and 60 minutes.
Serum cortisol concentration ≥498 nmol/L (18 micrograms/dL) is considered a normal response.
What is the insulin tolerance test
0.05 to 0.15 units of insulin/kg is administered intravenously and serum glucose, cortisol, and GH are measured before and after 15, 30, 60, 90, and 120 minutes of injection.
In normal subjects, serum cortisol increases to ≥498 nmol/L (18 micrograms/dL) if the serum glucose falls to 5 micrograms/L in the setting of hypoglycaemia (glucose
What is the water deprivation and desmopressin response test
Deprived of fluids for 8 hours
Measure osmolarity every 4 hours, urine volume and osmolarity every 2 hours
Then given desmopressin IM, measurements over next 4 hours
If central DI->kidneys response and develop concentrated urine
In hypo: low paired urine and plasma osmolalities; low urinary sodium; low urine specific gravity (3 L/24h)
Management
Address underlying cause
Other than GH and ADH->replacement is the target hormones of the pituitary produced
ACTH deficiency-> maintenance hydrocortisone or prednisolone + IV/IM for stress events. Have emergency bracelet
Thyroid->levothyroxine after adrenal (ACTH replacement)
GnRH deficient:
Female X fertility desired->transdermal estrogen + progesterone
Female +fertility desire->gonadotropins
Male Xfertility->testosterone
Male +fertility->gonadotropins
GH-> somatropin (recombinant human growth hormone)
ADH->desmopressin
Anti-CTLA-4 antibody therapy with hypophysitis-> high dose glucocorticoid
Why must ACTH deficiency be diagnosed and treated prior to thyroid replacement
Levothyroxine may provoke addisonian crisis due to +cortisol clearance
