Conditions of the Endocrine System Flashcards
Describe the condition of hypertcortisolism
Definition:
- umbrella term for a range of conditions characterized by excessive circulating cortisol levels
- Cushing’s disease: caused by increased ACTH secretion from anterior pituitary
- Cushing’s syndrome: occurs independently of ACTH secretion
Aetiology:
- Cushing’s Disease: usually caused by a pituitary microadenoma (benign hormone secreting tumour in anterior pituitary)
- Cushing’s Syndrome: usually iatrogenic (glucocorticoid hormone therapy)
- other: tumour of adrenal cortex, neuroendocrine tumours of the lung (SCLC) that produce ACTH
SSX (caused by increased glucocorticoid activity)
- tunical obesity
- abdo striations
- buffalo hump
- ‘moon face’ with flushed red cheks
- muscle atrophy
- myalgia, arthralgia
- osteoperosis and bone fractures
- insulin resistance
- poor wound healing and skin infections
- if zona reticularis involved, SSX of hyperandrogenism (hirsuitism, menstrual irregularity)
Management:
- if untreated 50% fatality rate within 5 years
- pituitary / adrenal / neuroendocrine tumours: surgery, radio and/or chemotherapy
- iatrogenic: discontinue glucocorticoid therapy
Which types of tumours can cause hypercortisolism?
- pituitary microadenoma
- 70% of cases
- benign hormone secreting tumour of anterior pituitary gland - tumour of adrenal cortex
- neuroendocrine tumours of the lung (SCLC / small cell lung carcinoma)
- secrete hormones including ACTH
Describe the condition of adrenal cortical hypofunction
Definition:
- inability of adrenal cortex to produce sufficient cortical hormones
Classifications:
- Primary adrenocortical insufficiency
- high ACTH levels, decreased cortisol
- called Addison’s disease
- caused by intrinsic dysfunction of adrenal cortex (usually autoimmune attack) - Secondary adrenocortical insufficiency
- low ACTH and cortisol levels
- caused by pituitary or hypothalamic dysfunction or after glucocorticoid therapy
SSX:
- decreased mineralocorticoid activity (dehydration, hypotension, hyperkalaemia)
- decreased glucocorticoid activity (hypoglycaemia, postural hypotension)
- systemic (severe fatigue, weakness, weight loss, GI disturbance)
- skin changes (hyperpigmentation caused by excess ACTH secretion, vitiligo)
Management:
- hormone supplementation (cortisol for glucocorticoids, fludocortisone for mineralcorticoids)
Acute adrenaocortical insufficiency /Addisonial crisis / adrenal crisis:
- medical emergency
- IV fluids and cortisol
- life threatening emergency associated with severe hypotension, hyperkalaemia, hypoglycaemia
What is Addison’s disease?
- another term for primary adrenocortical insufficiency (adrenal cortical hypofunction)
- caused by intrinsic dysfunction of adrenal cortex
- 80% of cases caused by autoimmune attack
- characterized by normal ACTH and low cortisol levels
What is ACTH and how is it implicated in the conditions hypercortisolism and adrenal cortical dysfunction?
ACTH:
- adreno corticotrophic hormone
- produced by anterior pituitary gland
- stimulates release of cortisol and androgens
In hypercortisolism (Cushing’s Disease):
- increased ACTH secretion from anterior pituitary
- causes excessive amounts of circulating cortisol
In primary adrenocortical insufficiency (Addison’s)
- ACTH levels are normal, but cortisol levels are high because of adrenal cortex dysfunction
In secondary adrenocortical insufficiency:
- ACTH levels are low, causing low cortisol levels
- caused by pituitary or hypothalamic dysfunction
What are the symptoms of abnormally high cortisol levels (hypercortisolism) and abnormally low cortisol levels (adrenal cortex hypofunction)
High:
- tunical obesity, moon face, buffalo hump
- muscle atrophy, osteoperosis
- myalgia, arthralgia
- insulin resistance
- HTN
- poor wound healing and skin infections
Low:
- severe fatigue
- weight loss
- GI disturbances
- hyperpigmentation
Describe the condition of phaeochromocytoma
Definition:
- adrenal tumour arising from chromaffin cells of adrenal medulla
Pathophysiology:
- most common cause of excess catecholamine production (epinephrine, norepinephrine)
SSX:
- CVD (HTN, AMI, stroke, AAA, heart failure, palpitations)
- systemic (pallor, sweating, weight loss)
- GI (abdo pain, vomiting, constipation)
- other (severe HA, anxiety, tremours)
Management:
- can cause death by catastrophic hypertensive crisis or fatal cardiac arrythmias
- surgical resection
- long term adrenergic blockade
Which group of hormones is affected by phaeochromocytomas?
Phaeochromocytomas:
- adrenal tumour arising from chromaffin cells
- cause increased catecholamine production (epinephrine, norepinephrine)
Describe the condition of simple / non-toxic goitres
Definition:
- enlarged thyroid gland
- thyroid function maintained
Classifications:
- simple diffuse (uniform enlargement) - most common in young women, pregnant women
- simple multinodular (enlargement with nodule formation)
Aetiology:
- iodine deficiency
- most common cause
- higher levels of TSH are secreted to maintain normal levels of T3 and T4
- causes hyperplasia of follicular cells in thyroid and resulting enlargement - Other:
- ingestion of goitrogens (lithium, tobacco)
- pregnancy, OCP
- early stage Hashimoto’s thyroiditis
SSX:
- simple diffuse
- soft and symmetrical goitre
- neck tightness with swallowing
- non tender
- no bruit - simple multinodular
- can become very large
- if haemorrhaged into a nodule: pain and oedema
- if compressing mediastinal structures: cough, dysphagia, stridor, oedema
Management:
- asymptomatic simple: observation
- iodoine supplementation (helps childhood goiotres, doesn’t impact adulthood goitres)
- if compressive SSX: partial thyroidectomy (high risk of recurrence)
What are dietary sources of iodine, and how is iodine implicated in goitres?
Dietary sources:
- dairy, eggs, seafood
Iodine:
- synthesizes production of T3 and T4 from thyroglobulin in thyroid glands
- if insufficient iodine: T3 and T4 levels drop, so anterior pituitary secretes more TSH (thyroid stimulating hormone)
- elevated TSH causes hyperplasia of follicular cells
Describe the condition of hypothyroidism
Definition:
- deficiency of T3 and T4 thyroid hormones
Classifications:
- Primary:
- caused by thyroid gland failure
- most common cause: Hashimoto’s thyroiditis (autoimmune)
- other causes: iatrogenic, congenital, iodine deficiency - Secondary:
- caused by TSH deficiency
- caused by pituitary adenoma, pituitary surgery - Tertiary:
- caused by TRH deficiency
- caused by hypothalamic dysfunction
SSX:
- puffiness and pallor = sterotypical features
- myxedema (non-pitting oedema) especially in hands, feet and eyelids (periorbital oedema) - caused by GAG / glycosaminoglycan accumulationo in various body tissues
Describe the condition of Hashimoto’s thyroiditis
Definition:
- autoimmune disease of thyroid gland causing hypothyroidism
Incidence:
- most common type of primary hypothyroidism in Aus
- 10 x more common in females
- typically onset in middle age
Precipitating factors:
- high iodine supplementation
- lithium amiodarone drugs
Pathophysiology:
- autoimmune disorder
- lymphocyte mediated inflammation and fibrosis of thyroid
- secretion of IgG antibodies against thyroglobulin and thyroid peroxidase
- causes goitre (early stage)
- causes thyroid atrophy (late stage)
Describe the condition of thyrotoxicosis
Definition:
- clinical state caused by an excess of thyroid hormones
Classifications:
- toxic diffuse goitre (Grave’s)
- toxic multinodular goitre
- toxic solitary nodule
Aetiology:
- usually caused by hyperthyroidism
- can also be caused by levothyroxine ingestion
SSX:
- goitre
- diffuse enlargement
- audible bruit - ocular changes (GAG accumulation)
- lid retraction and bulging eyes
- corneal ulceration and conjunctivitis
- excessive lacrimation
- diplopia
- decreased visual acuity - increased metabolic rate
- heat intolerance
- weight loss
- sweating - GIT
- increased appetite and thirst
- hyperdefecation, diarrhea - CVS / Respiratory
- palpitations and atrial fibrillation
- exacerbated asthma - neuro
- nervousness, emotional lability, psychosis
- hyper-reflexia, tremor
- muscle atrophy - reproductive
- menstrual irregularities
- loss of libido - skin
- GAG accumulation in skin of legs causes pretibial skin myxedema and thicke
Management:
- anti-thyroid drugs, beta-blockers, radioactive iodine
- surgery: sub-total thyroidectomy (risk for hypothyroidism, damage to laryngeal nerves or parathyroid gland)
- good prognosis with management, risk for hypothyroidism
Describe Grave’s disease
Definition:
- toxic diffuse goitre
- autoimmune disease
- most common cause of thyrotoxicosis (excess of thyroid hormones)
Incidence:
- 8 x more common in females
Risk factors:
- familyl history, high dose iodine supplementation, major stressors causing an autoimmune response
Pathophysiology:
- autoantibodies present in 50% of cases are directed against thyroid stimulating hormone receptors
- causes goitre production and elevated T3 and T4 levels
Describe the condition of thyroid cancer
Incidence:
- 7th most common cancer in women
- much more common in women
Risk factors:
- family history
- benign thyroid disease
- exposure to ionizing radiation (20 years latency)
Classifications:
- papillary carcinoma (80%, begins as a solitary nodule and spreads through gland)
- follicular, medullary and anaplastic carcinomas
SSX:
- rapid onset nodule enlargement (firm and non-tender)
- large tumours can cause discomfort, dysphagia, Horner’s syndrome
- metastatic spread: Cx lymphadenopathy
Management:
- excellent prognosis: if tumour under 2cm, patient under 50 and no spread, no change to life expectancy
- surgical resection
- hemi or total thyroidectomy
Describe the condition of hyperparathyroidism
Definition:
- increased PTH (parathyroid hormone) secretion
Classifications:
- Primary
- adenoma of a single PT gland (most common)
- causes increased PTH secretion and increased serum calcium levels - Secondary:
- secondary to a pathology causing low serum calcium levels (rickets, malabsorption)
- PTH levels increase as a response to low serum calcium levels
SSX: (bones, stones, abdo groans, psychic moans and fatigue overtones)
- 50% asymptomatic, SSX usually mild
- SSX caused by hypercalcaemia
- Bones
- reduction in bone density (osteoclastic bone resorption and fibrous replacement)
- bone pain
- fracture
- arthralgia - stones
- nephrolithiasis - abdo groans
- anorexia
- nausea
- constipation
- polydipsia
- polyuria - psychic moans
- HA
- insomnia
- irritability
- depression
- paraesthesia
- poor concentration / memory loss - fatigue overtones
- maliase
- muscle cramps
- weakness
- hyporeflexia - cardiac changes
- hypercalcaemia increases cardiac contractility and excitability
- arrythmias and HTN
Management:
- monitor if asymptomatic
- symptomatic or pregnant: surgical excision
Describe the condition of hypoparathyroidism
Definition:
- insufficiency of PTH
- causes hypocalcaemia
Aetiology:
- removal of parathyroid adenoma causing suppression of other parathyroid glands
- thyroid surgery
- autoimmune disease, infection
SSX:
(hypocalcaemia increases excitability of sensory and motoor nerves)
- muscular:
- increased tone
- hyperreflexia
- Chvostek sign and Troussea phenomenon - neuro
- paraesthesia
- irritabiity
- confusion
- premature cataracts - cardiac changes
- decreased cardiac contractility and excitability
Life threatening SSX: tetany of laryngeal muscles
Management:
- no effective PTH replacements
- calcium supplementation
Which conditions are involved in pathological changes to serum calcium levels?
- Hypercalcaemia:
- caused by primary hyperparathyroidism (adenoma of a parathyroid gland)
- causes increased PTH secretions and increased serum calcium levels - Hypocalcaemia
- caused by hypoparathyroidism (decreased PTH secretion causes decreased serum calcium levels)
- also present in secondary hyperparathyroidism (pathology causing low serum calcium levels already present, causes increased PTH secretions to try to raise calcium)
What are the SSX of hypercalcaemia and hypocalcaemia?
Hypercalcaemia (primary hyperparathyroidism):
- causes increased cardiac muscle contractility and excitability
- bones, stones, abdo groans, psychic moans, fatigue overtones
Hypocalcaemia (hypoparathyroidism, secondary hyperparathyroidism:
- causes decreased cardiac muscle contractility and excitability
- increases muscle and nervous excitability
Which conditions cause hypercortisolism, and which cause hypocortisolism?
Hypercortisolism:
- Cushing’s Disease (caused by increased ACTH secretion) - usually caused by a pituitary microadenoma
- Cushing’s Syndrome (independent of ACTH secretion)
- tumour of adrenal cortex, neuroendocrine tumour of lungs
Hypocortisolism:
- primary adrenocortical insufficiency (Grave’s disease) caused by adrenal cortex dysfunction
- secondary adrenocortical insufficiency - caused by pituitary or hypothalamic dysfunction
What are the symptoms of hypercortisolism and hypocortisolism?
Hypercortisolism
- caused by Cushings, or pituitary or neuroendocrine tumour
- tunical obesity, buffalo hump, moon face
- myalgia, arthralgia
- muscle atrophy, osteoperosis
- insulin resistance
- HTN
- poor wound healing and skin infections
Hypocortisolism:
- caused by primary adrenocortical insufficiency (Addison’s) or secondary adrenocortical insufficiency
- severe fatigue, weakness, weight loss
- GI disturbance
- hyperpigmentation
- acute adrenal crisis: medical emergency (can be fatal)
Which endocrine pathology affects catecholamine production?
Phaeochromocytoma:
- tumour of adrenal medulla (from chromaffin cells)
- causes excessive catecholamine production
Which endocrine pathologies affect levels of thyroid hormones?
Hypothyroidism:
- primary (most common: Hashimoto’s thyroiditis)
- secondary (caused by pituitary adenoma or pituitiary surgery)
- tertiary (caused by hypothalamic dysfunction
Hyperthyroidism / Thyrotoxicosis:
- toxic diffuse goitre (Grave’s)
- toxic multinodular goitre
- toxic solitary nodule
What are the symptoms of hyperthyroidism and hypothyroidism?
Hypothyroidism:
- puffiness and pallor
- GAG accumulation causes non-pitting oedema (myxedema)
Hyperthyroidism:
- goitre
- ocular changes (bulging eyes, diplopia, conjunctivitis, lacrimation)
- increased BMR
- increased appetite and thirst, hyperdefecation / diarrhea
- CVS/resp: palpitations, atrial fibrillation, exacerbates asthma
- neuro: nervousness, psychosis, tremor, hyper-reflexia, muscle atrophy
- reproductive: menstrual irregularities, loss of libido
- GAG accumulation in skin of legs: pretibilal skin myxedema and thickening
What are GAGs and how are they involved in pathologies of the thyroid gland?
GAGs:
- glycosaminoglycans
- proteoglycans normally found in ECM of connective tissue
Hypothyroidism:
- GAGs accumulate in body tissues due to reduced rate of protein breakdown
- causes myxedema of hands, feet and eyelids
Hyperthyroidism:
- GAGs accumulate in skin of legs
- causes pretibial myxedema
