S8 L2 - Pituitary Disorders Flashcards
- *Pituitary Disorders**
- Main cause for pituitary disorders
- Two types of tumours and symptoms of each type of tumour
They are mainly caused by pituitary adenoma, a benign pituitary tumour.
These tumours can be:
- Non-functioning (don’t produce anything), but cause inadequate production of one or more pituitary hormone due to the physical pressure of the growing tumour on the glandular tissue
Symptoms of a pituitary adenoma (due to mass effect on local structures):
headaches, nausea, visual problems, vomiting
- Functioning tumours: ‘hyper-secreting’ tumours
Rarer, clinical symptoms depend on which pituitary hormone they are over-secreting
Symptoms of a pituitary adenoma (due to mass effect on local structures)
headaches, nausea, visual problems, vomiting
How to investigate pituitary tumours
3 things
- MRI scan
- Assessment of visual fields
- Blood tests measuring hormone levels
- *Investigations:**
1. Assessment of field of vision
INVESTIGATIONS: Assessment of field of vision
- Field of vision will suggest where pituitary tumour is:
- *Investigations:**
2. INVESTIGATIONS: Dynamic assessment of HPA and GH excess - Adrenal axis deficiency
- Adrenal axis for excess
- GH deficiency
- GH excess
INVESTIGATIONS: Dynamic assessment of HPA and GH excess:
- Stimulation test: suspected hormone deficiency
- Suppression test: suspected hormone excess
*Remember these and then work out the test
Adrenal axis:
- Deficiency: 2 tests:
—- SynACTHen test: Direct stimulation of adrenal by ACTH (use synACTHen test) – see if adrenal gland produces cortisol in response to this
—- Insulin Stress test: Inject adrenaline, this will lower insulin, measure if ACTH rises. ACTH is meant to rise when low insulin levels (think – stress hormone)
- Excess:
—- Dexamethasone suppression test: Suppress ACTH axis with steroids (as cortisol is a steroid). Give patient steroid, measure if cortisol decreases. Cortisol should decrease in this example.
GH axis:
- Deficiency:
—- Insulin stress test: GH should increase
GH increases when low glucose
- Excess:
—- Glucose tolerance test: GH should decrease
GH decreases when high glucose
—- Also, Elevated IGF-1 level (age related reference range)
—- Growth Hormone Day Curve – elevated mean GH
- *Hypopituitarism**
- Cause
- Which order are the hormones effected…
- Cause: Pituitary adenoma putting pressure on the pituitary glandular tissue – the ‘lump’ means the hormone from the hypothalamus (the releasing and inhibiting hormones) can’t get from the hypothalamus to the anterior pituitary gland.
Brief effect of this:
- *GH deficiency**
- Symptoms
- Causes in adults
- Causes in children
- Blood test
(usually subtle)
Symptoms: Decreased exercise tolerance, decreased muscle tone, increased body fat, reduced sense of well-being
Hard to diagnose: because GH is released in pulses
Cause in adult: Usually pituitary adenoma
Cause in children -> see PITUARY DWARFISM: Usually idiopathic (may be genetic mutation or autoimmune inflammation). In age 1-10, result in poor growth and short stature, can be treated with GH (manufactured by recombinant DNA technology)
Blood test: GH/IGF-1, more info under dynamic assessment of HPA and GH axes
- *Pituitary dwarfism**
- Description
- Causes
- Signs and symptoms
- Treatment
Description:
In childhood
Proportionate type of dwarfism
Complete or partial deficiency
Cause: USUAULLY IDIOPATHIC (may be genetic mutation or autoimmune)
GH deficiency (Somatotropin deficiency)
Signs and symptoms: Height below 3rd percentile on standard growth charts
Growth rate slower than expected for age
Delayed or no sexual development during teen years
Treatment: GH therapy (manufactured by recombinant DNA technology)
- *LH and FSH deficiency**
- Cause
- Signs and symptoms
- Blood test
Cause: Pituitary adenoma
Signs and Symptoms:
Low libido, infertility, oligomenorrhea (infrequent menstrual periods), loss of sexual characteristics (e.g. loss of pubic hair), amenorrhea (when women doesn’t have her periods in people at reproductive age). In men – decrease libido, impotence
Blood test: LH, FSH. Testosterone – men, oestrogen – women (basal blood test – has to be measured at specific time)
- *TSH deficiency:**
- Cause
- Symptoms
- Blood test
- *Cause:** Pituitary adenoma, can lead to hypothyroidism (this cause of TSH deficiency is RARE)
- *Symptoms:** Feeling cold, weight gain, bradycardia
- *Blood test:** TSH levels, fT4 (basal blood test – has to be measured at specific time)
- *ACTH deficiency:**
- Cause
- Symptoms
- Blood test
Cause: Pituitary adenoma (this cause of cortisol deficiency is RARE)
Symptoms: Leads to low cortisol - Tiredness, dizziness, low blood pressure, low sodium
THIS CAN BE LIFE-THREATENING (ADDISONIAN CRISIS)
Blood test: 09:00 Cortisol blood test (dynamic blood test – try to stimulate the hormone to see if it responds as expected)
THIS IS NOT ADDISONS DISEASE
- *Hyperprolactinaemia: (caused by mass effect – non-functioning pituitary adenoma)**
- Cause
- Symptoms
- Treatment
- Blood
- *Cause:** Non-functioning pituitary adenoma (mass effect) (see other causes below)
- *Symptoms** – same as under hyperprolactinaemia under hyperpituitarism
- *Treatment:** SURGERY (as the mass have to be removed) – drugs will not work against a non-functioning mass!!
- *Blood:** Serum prolactin (Basal blood test – can be measured at ANY time)
- *ADH deficiency:**
- Cause
- Symptoms
- *Cause:** Hypothalamic tumour or pituitary tumour that has extended up into the hypothalamus. Or, cranial radiotherapy, pituitary surgery, autoimmune infiltration, infections like meningitis
- *Symptoms:** Excess secretion of dilute urine, resulting in dehydration, increased sensation of thirst.
- *Hyperpituitarism:**
- Cause
- Hormones most affected
Causes:
Hypersecreting pituitary adenoma
Hormones most affected:
Three hormones most commonly affected: prolactin, GH, ACTH
- *Hyperprolactinaemia:** (caused by pituitary adenoma secreting prolactin)
- Two types of prolactinoma
- Causes
- Symptoms
- Treatment
Macro-prolactinoma – large tumour (>1cm)
Micro-prolactinoma – small tumour (<1cm)
Cause: Prolactinoma (a pituitary adenoma that secretes prolactin), [also a non-functioning pituitary adenoma via mass effect – covered in different card]. Other causes: pregnancy, suckling during breastfeeding, stress and exercise, medication (e.g. anti-sickness and anti-psychotic drugs are dopamine antagonists)
Increased conc. of prolactin (PRH), increases negative feedback on the hypothalamus, this increases production of PIH (Prolactin inhibiting hormone, also called dopamine).
ALSO: Prolactin directly inhibits LH secretion (mechanism of this – increase prolactin, increase of PIH, decreases the release of GnRH: this causes diminished LH and FSH production too).
Symptoms: Galactorrhoea (milky discharge from breast unassociated with child birth or breast feeding), gynecomastia, hypogonadism, amenorrhea (women – loss of menstrual cycle), erectile dysfunction,
Men usually presented later – as women get concerned and see doc when noticed they’ve lost their period.
Treatment: Cabergoline (dopamine receptor agonist), this will shrink the tumour - Don’t operate on a hyperprolactinaemia
NOTE – Must work out if this is a prolactinoma or a pituitary adenoma causing it through mass effect, as treatment options are different.
Usually: If prolactin is <5000 more likely to be due to ‘stalk effect’
If prolactin is >5000, more likely to be due to active prolactin secretion (prolactinoma)
NOT ALWAYS THOUGH
- *GH excess:**
- Cause
- Reason for symptoms
Cause: large growth-hormone secreting pituitary adenoma
Local mass effects (due to pressure): headaches, visual field defects, cranial nerve palsies
Reason for symptoms: Excess GH, increases IGF-1 production. IGF-1 causes symptoms of ACROMEGALY (see above) in adult and GIGANTISM (see above) in children
- *Acromegaly**
- Causes
- Signs
- Three types of treatment from acromegaly
- Long-term complications if untreated
Acromegaly
Causes: Often caused by a pituitary adenoma - GH is in excess in adulthood
Growth plates have fused, so height is not affected
Signs: Broad nose, coarse facial features, thick lips, prominent supraorbital ridge, enlarged head and feet, greasy skin, excessive sweating, deepening voice
Three types of treatment from acromegaly: surgery to remove the adenoma (called transsphenoidal hypophysectomy – through nose and sphenoid bone into the sphenoidal sinus cavity), radiation therapy, drug therapy (e.g. GH receptor antagonist or somatostatin (GHIH) to prolong GH suppression)
Long-term complications if untreated:
Premature cardiovascular death, increase risk of thyroid cancer and colonic tumours, disfiguring body changes, hypertension, diabetes (as GH antagonises insulin)
- *ACTH excess:**
- Cause
- Signs and symptoms
- Blood test
Cushing’s disease
Cause: ACTH-secreting pituitary tumour, steroid medication
Signs and symptoms:
pic
Blood test: Record cortisol levels at midnight for Cushing’s disease
