Pituitary Disorders Flashcards
Definition pituitary microadenoma?
< 1cm size
What is Lymphocytic Hypophysitis
Pituitary mass that occurs post-partum
-secondary hypoadrenalism due to ACTH deficiency
- can cause visual field issues
Causes for hypopituitarism
- Congenital
- Neoplastic
- Vascular
- Inflammatory/ infiltrative
- Infection
- Post –irradiation
- Miscellaneous
Pituitary Apoplexy
- Haemorrhage or infarction into a pre-existing adenoma
- Hypertension increases risk
- Severe headache, visual disturbance, altered consciousness, cranial nerve palsies
- Acute ACTH deficiency may be life-threatening (Always give steroids)
- CT best in acute (<48 hours), thereafter MRI
- Conservative v surgical approach
Pituitary hormone abnormality common after irradiation?
Growth hormone deficiency
Chance of checkpoint inhibitor hypophysitis
highest with CTLA-4
Most common functioning pituitary adenoma?
Lactotroph (50%)
Natural pattern of growth hormone release
Pulsatile secretion
– 10 pulses per day
– 90 minutes per pulse
– 2 hours between pulses
– Increased amplitude in women
Circadian
– Maximal in second half of night
– Slow wave (stage 3 & 4)
Stimuli for Growth Hormone release
– Stress/exercise
– Hypoglycaemia
– Amino acids (protein)
– Sex steroids
Physiologically
* GHRH
Negative Feedback
* Somatostatin
* Growth Hormone
* IGF-1
* Ghrelin stim
* FFA’s
Cause(s) for acromegaly?
- GH producing pituitary tumour - 98% (70% with have invasive macroadenoma)
- GHRH tumours rare,
- Ectopic GH production – 1 case
Screening test for acromegaly?
- IGF-1 - useful screening test
- Oral glucose tolerance test (75 gram glucose, 2nd line test)
- IGFBP-3 also a sensitive marker of GH excess
Treatment options for GH producing pituitary adenomas
Surgery
Radiotherapy
Medications
* Dopamine agonists (Cabergoline, Bromocriptine)
* Somatostatin analogues (octreotide, lanreotide …)
* Growth hormone antagonists
Consequences of acromegaly?
- Mortality increased 2-fold
– 60% cardiovascular
- Diabetes 30%
- Cardiomyopathy
- Arrhythmias
- Hypertension
- Obstructive sleep apnoea
- Hypertriglyceridaemia
- Colorectal cancer
Adult GH Deficiency Causes
– Pituitary tumour (50%)
– Craniopharyngioma (13%)
– Irradiation (2%)
– Idiopathic (12%)
– Other (16%)
Adult GH Deficiency Issues
- Depressed mood
- Increased anxiety
- Lack of energy levels
- Social isolation
- Increased body fat, particularly central adiposity
- Decreased muscle mass
- Decreased insulin sensitivity
- Increased prevalence of impaired glucose tolerance
- Increased LDL cholesterol and decreased HDL cholesterol
- Accelerated atherogenesis
- A variable decrease in cardiac muscle mass
- Impaired cardiac function
- Decreased total and extracellular fluid volume
- Decreased bone density, associated with an increased risk of fracture
Causes of increased prolactin?
Spurious: Macroprolactinaemia (Large (50kDa) and very large (150kDa) but biologically inactive forms of prolactin)
Physiologic
* sleep, stress, pregnancy, breast-feeding
Pharmacologic
* DA receptor blockers: Phenothiazines, Butyrophenones Tiaprides: Metaclopramide, domperadone, cisapride
* DA synthesis inhibitors – methyldopa
* Opioids
* H2 antagonists
* Imipramine, Amitryptilene
* Seratonin reuptake inhibitors - Fluoxitene
* Ca antagonists - Verapamil
* Oestrogens
Pathologic
* Hypothalamic / Pituitary Stalk Lesions - craniopharyngioma, infiltrative disease, stalk section.
* Pituitary Disease - Prolactinoma’s, Mixed tumours, Non functioning tumours
* Other - Primary hypothyroidism, chronic renal failure, cirrhosis, neurogenic
Clinical Features Increased Prolactin
Women (micro more common than macro)
– Galactorrhoea 50%
– Menstrual irregularity (25% of those with menstrual disturbances)
– Infertility
– Recurrent miscarriage
– Hirsutism – raised adrenal androgen production
– Osteopaenia
- Men (macro more common than micro)
– Loss of libido (2% of those with reduced sexual potency)
– Infertility
– Galactorrhoea 20%
