Pituitary and thyroid diseases Flashcards
ILO 8.8a: be familiar with the underlying disease processes of the common medical disorders affecting the body
describe the endocrine system
a complex network of glands that produce and release hormones that control and co-ordinate many important processes in the body
what hormones do the adrenal glands produce?
- cortisol
- aldosterone
- adrenaline
- noradrenaline
what is the role of the hypothalamus? where is it located? what hormones does it produce?
part of the lower brain which tells the pituitary gland when to release hormones
* produces releasing hormones - TRH (thyrotropin releasing hormone), GnRH (gonadotropin releasing hormone), CRH (corticotropin releasing hormone)
what hormoes do the islet cells of the pancreas produce?
- insulin (beta cells)
- glucagon (alpha cells)
what do the paratyroid glands do?
controls bood calcium levels
what does the pituitary gland do?
controls other glands to produce hormones
what does the thyroid gland do?
produces hormones that control metabolism, growth and development
why can disorders of the endocrine system occur?
3
- hormone levels are too high
- hormone levels are too low
- body does not respond to hormones in the expected way
what can endocrine diseases cause?
- too much or too little hormone production
- development of tumours
where is the pituitary gland located?
at the base of the brain, below the hypothalamus
what hormoes does the anterior pituitary gland produce?
- TSH - thyroid stimulating hormone
- ACTH - adrenocorticotropic hormone
- GH - growth hormone
- LH, FSH, prolactin
what hormones does the posterior pituitary gland produce?
- ADH - anti-diuretic hormone
- oxytocin
what is the difference between a functional and non-functional adenoma?
- functional adenomas actively produce and release excess hormones
- non-functional adenomas do not secrete significant amounts of hormone and can cause symptoms by growing and compressing glands
what affect can pituitary tumours have on the optic nerve? how can this be treated?
- pituitary adenomas can grow to compress the optic nerve and cause vision problems
- if the tumour affects the optic chiasm, it can affect vision in both eyes
- treated with trans-sphenoidal surgery
describe the negative feedback loop of growth hormone
- hypothalamus releases GHRH (growth hormone releasing hormone)
- GHRH acts on the **anterior pituitary **gland to release GH (growth hormone)
- GH is converted to IGF-1 (insulin growth factor) in the liver and decreases secretion of GH by stimulating stomatostatin
- excess GH also inhibits release of GHRH
what happens when a person has insufficient growth hormone?
- growth failure in children
- metabolic changes in adults - increased fat, reduced vitality
what happens when a person has excess growth hormone?
- gigantism in children
- acromegaly in adults
what causes acromegaly?
- insidious onset
- benign pituitary tumour
what are the physical features of acromegaly?
- coarse features
- enlarges supra-orbital ridges
- broad nose
- thickened lips and soft tissues
what conditions are associated with acromegaly? why?
- carpel tunnel syndrome - enlarged hands
- type 2 DM - GH causes raised blood glucose levels so insulin resistance
- cardiovascular disease (ischaemic HD, acromegalic cardiomyopathy) - thickening of heart muscle
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what are the dental aspects of a person with acromegaly?
- enlarged tongue
- interdental spacing
- ‘shrunk’ dentures (mouth grows too large)
- reverse overbite / class 3 occlusion
what are the tyroid hormones and what do they do?
T3 and T4 - regulate metabolism
what is hyperthyroidism? what does it cause?
an excess of T3 and T4 produced, causing increased metabolism
what are the signs of hypertyhroidism?
5
- warm, moist skin
- tachycardia, atria fibrillation
- increased blood pressure
- tremor and hyperreflexia
- eyelid retraction and lid lag
what are the symptoms of hyperthyroidism
6
- hot and excessive sweating
- weight loss
- diarrhoea
- heart palpitations
- muscle weakness
- irritable, manic, anxious
what are the causes of hyperthyroidism?
6
- Grave’s disease
- toxic multi-nodular goitre
- toxic adenomas
- thryoiditis
- exogenous thyroid hormone intake
- pituitary tumour
what is Grave’s disease? what people is it more common in? what are the symptoms?
auto-immune condition which causes the tyroid gland to produce more hormones
* common in women over 30
* diffuse goitre
* opthalmopathy - oedema and erythema of periorbital and conjunctivae, upper eyelid retraction
how can pituitary tumours cause hyperthyroidism?
benign pituitary adenoma which produces TSH
describe how thyroid levels are regulated
- hypothalamus produces TRH (thyrotropin releasing hormone)
- TRH works on the anterior pituitary gland to release TSH (thyroid stimulating hormone)
- TSH works on the thyroid gland to produce T3 and T4
- T4 negatively regulates the production of TRH in the hypothalamus
- T3 negatively regulates the production of TSH in the anterior pituitary
what is hypothyroidism and what does it cause?
a lack/no T3 or T4 hormone released which causes reduced metabolism
what are the signs of hypothyroidism?
6
- dry, coarse skin
- bradycardia
- hyperlipidaemia (high colesterol)
- confusion
- goitre (Hashimoto’s)
- delayed reflexes
what are the symptoms of hypothyroidism?
9
- tiredness
- cold intolerance
- weight gain
- constipation
- hoarse voice
- puffed face and extremities
- angina
- slow/poor memory
- hair loss
what are the primary and secondary causes of hypothyroidism?
6,1
primary
* autoimmune thyroiditis (Hashimoto’s)
* idiopathic atrophy
* radioiodine treatment / thyroidectomy surgery
* iodine deficiency
* drugs
* congenital
secondary
* hypothalmic/pituitary disease
what is Hashimoto’s thyroiditis and what are the presenting features?
- autioimmune disease usually genetic which gradually destroys the thyroid gland
- presents with goitre and other hypothyroidism features
how can a pituitary tumour cause hypothyroidism?
- there is limited space for expansion of pituitary gland in Sella Tunica
- pituitary tumour can expand and compress normal pituitary tissue
- the compressed cells produce abnormally low TSH, leading to less T3 and T4 produced and therefore hypothyroidism
what are the investigations for thyroid disease?
3
- blood tests - T3, T4, TSH levels
- imaging - ultrasound, radiopaque scan
- tissue samples - fine needle aspiration/biopsy (FNA, FNB)
what blood results would you find with primary hyperthyroidism?
- high T3 and T4
- low TSH
what blood results would you find with secondary hyperthroidism?
- high T3 and T4
- high TSH
what blood results would you find with primary hypothyroidism?
- low T4
- high TSH
what blood results would you find with secondary hypothyroidism?
- low T4
- low TSH
what are the treatments for hyperthyroidism?
- medication - carbimazole, beta blockers
- radioiodine 131i
- surgery - partial thyroidectomy
what is the treatment for hypothyroidism?
- T4 (thyroxine) tablets
how does thyroid cancer usually present?
- thyroid swelling
- papillary or follicular in younger patients
- undifferentiated in elderly
- cold nodes on radioiosotope scan
what are the dental aspects of thyroid disorders? how do hypo and hyperthyroid patients differ?
- goitre detectable at the dentist
- hyperthyroidism - pain, anxiety and psychiatric problems, caution for treatment until controlled
- hypothyroidism - avoid use of sedative if severe, can present as burning mouth
