Panhypopituitarism Flashcards
What are the hypothalamic causes of hypopituitarism?
Tumors
- Craniopharyngioma
- Metastasis from malignant tumors e.g. lung and breast CA
Infarct / Stroke (rare)
Radiation therapy
- Can lead to hypothalamic / pituitary dysfunction or both
Is dose and time-dependent, and may not become apparent until many years s/p treatment
- Hence impt for pt post-therapy to go for regular screening
Infiltrative lesions :
- Marked thickening of infundibulum on MRI is a common finding
- Conditions include Sarcoidosis and Langerhans cell histiocytosis
Infections: TB, Candida, Hanta virus
Traumatic brain injury (TBI)
What are the pituitary causes of hypopituitarism?
Mass lessions
- Most commonly by a non-secretory pituitary macroadenoma > 1cm
- Commonly: HG, Prolactinoma, Non-Secreting pituitary tumor
Pituitary surgery – Pituitary function may be better or worse afterwards
Pituitary radiation
Sheehan syndrome
Pituitary apoplexy
Snake bite: Russell viper bites have been shown to cause hemorrhagic necrosis of the pituitary
Hemochromatosis : Gonadotropin deficiency is the most common endocrine abnormality
How does non secretory pituitary adenoma present?
Presents with loss of multiple anterior pituitary hormone deficiencies
- GH and gonadotrophins are usually first affected
- TSH and ACTH are usually last to be affected
A/w HYPERPROLACTINAEMIA due to Stalk Compression Syndrome
- Loss of dopaminergic inhibition from hypothalamus
- Don’t confuse this w/ prolactinoma 🡪 will p/w macroadenoma w/ Prolactinaemia >4-5x ULN; whereas in SCS prolactin levels usually 2x ULN
What is Sheehan’s syndrome and how does it present?
Infarction after postpartum haemorrhage, often severe as to cause hypotension and require multiple transfusions
In severe hypopituitarism, patient may develop lethargy, anorexia, weight loss, and inability to lactate during the first days/weeks after delivery
In mild hypopituitarism, there may be delay in recognition for many year
What is pituitary apoplexy and how does it present?
Sudden haemorrhage into the pituitary gland, often into a pituitary adenoma
This may produce severe headache, double vision and sudden severe visual loss, sometimes followed by acute life-threatening hypopituitarism.
Often pituitary apoplexy can be managed conservatively with replacement of hormones and close monitoring of vision, although if there is a rapid deterioration in visual acuity and fields, surgical decompression of the optic chiasm may be necessary.
How does a patient with growth hormone deficiency present?
- Growth Failure (during childhood) -> Dwarfism
- ↓ bone density
- Muscle atrophy & weakness
How does a patient with prolactin deficiency present?
Lactation Failure following delivery
Asymptomatic in Males
How does a patient with central TSH deficiency present?
- Weight gain
- LOA
- Cold intolerance
- Lethargy
- Constipation
- Dry skin
- Menstrual Change (Oligo/Menorrhagia)
How does a patient with 2’ adrenal deficiency present?
- HypoNa
- HypoTN
- Hypoglycaemia
- Lethargy
- Hypoandrogenism (in women)
How does a patient with ADH deficiency present?
Central DI 🡪 polyuria, polydipsia
How does a patient with oxytocin deficiency present?
No Effect
How does a male with 2’ hypogonadism present?
- Testicular Atrophy
- Gynecomastia
Infertility, Loss of libido
Menopausal / Andropausal S&S, Osteoporosis, CV S/E
How does a female with 2’ hypogonadism present?
Amenorrhea
What is Kallman’s syndrome?
Isolated gonadotrophin (GnRH) deficiency due to mutations in the KAL1 gene on the short arm of X Ch
Characterized by anosmia
What is septo- optic dysplasia?
- Congenital syndrome associated with mutations in the HESX1 gene 🡪 resulting in developmental abnormality of the forebrain
- Presents in childhood with a clinical triad of midline forebrain abnormalities, optic nerve hypoplasia and hypopituitarism.
What is ‘empty sella’ syndrome?
An ‘empty sella’ on pituitary imaging
This is sometimes due to a defect in the diaphragma and extension of the subarachnoid space (cisternal herniation) OR may follow spontaneous infarction or regression of a pituitary tumour
All or most of the sella turcica is devoid of apparent pituitary tissue, but, despite this, pituitary function is usually normal, the pituitary being eccentrically placed and flattened against the floor or roof of the fossa.
May be associated with a certain degree of decreased pituitary function, causing hypopituitarism
What is the investigations performed for GH deficiency?
First measure IGF-1 levels 🡪 will be low
Then perform Insulin tolerance test / glucagon stimulation test
- First, exclude CVD, epilepsy, and patients with severe untreated hypopituitarism
- Involves overnight fast followed by IV insulin 0.15U/kg at time 0
- Caution – must be done with care else may ppt severe neuroglycopenia 🡪 seizure, coma
- Glucose, cortisol and GH levels are measured at 0, 30, 45, 60, 90, 120min
- Is meant to ↑ GH and Cortisol!
What is the investigations performed for Gonadotrophin deficiency?
Measure serum LH & FSH
Men: testosterone + SHBG
Women: Estradiol
Females: the presence of regular menstrual cycles effectively rules out gonadotropin deficiency; no further diagnostic test is required.
What is the investigations performed for TSH deficiency?
do TFT – showing ↓ T3, ↓ T4, ↓ or normal TSH
What is the investigations performed for ACTH deficiency?
Administer an 8am cortisol + ACTH + Synacthen Test showing
- 8am cortisol & ACTH shows Hypocortisolism & low ACTH
- If acute central A-I: optimal rise in cortisol
- If chronic central A-I: suboptimal rise in Cortis
What is the investigations performed for prolactin deficiency?
check serum prolactin levels
What are the 2 hormones that needs to be replaced in a patient with pan hypopituitarism going for surgery for removal of adenoma?
The 2 main replaced hormones are Cortisol & Thyroxine
- Cortisol, so that pt doesn’t develop Addisonian crisis intra-op
- Thyroxine, so that pt doesn’t develop Myxedema Coma crisis intra-op
Always cortisol before thyroxine b/c:
- Cortisol has a permissive effect on thyroxine
- ↑ Thyroxine activity increases cortisol clearance 🡪 further lowers cortisol levels 🡪 ppt adrenal crisis
What are the indications for growth hormone replacement?
Children for growth!
Adults exhibiting excessive tiredness, muscle weakness, weight gain 🡪 improves psychological well being
How do you replace sex hormones in a young man?
we give testosterone (IM/Gel) for libido, sexual activity
- ALONE CANNOT BE ENOUGH
- If wants to father a child: give FSH & LH injections for spermatogenesis & testosterone production
