Hyperthyroidism Flashcards
hyperthyroidism
common?
affects ~2% of women (10 fold less in men)
Hyperthyroidism features
Weight loss, nervousness, heat intolerance, high cardiac output, hand tremors
Causes of hyperthyroidism
Primary hyperthyroidism due to hypersecreting thyroid tumour
Secondary due to excessive hypothalamic (TRH) or anterior pituitary (TSH) secretion
or, most commonly due to
Graves disease (50% of all cases)
Thyroid stimulating antibodies that mimic TSH
Symptoms/features of Graves disease
Often have protrusion of eyeballs (exopthalmos)
Hyperthyroidism Treatement
‘Ant-thyroid drugs’ that interfer with T3/T4 synthesis
Surgical removal or ressection of thyroid
Thyroid ablation using radioactive iodine
Will then require T4 replacement therapy for life
What are the adrenal Hormones
Secreted by adrenal medulla:
Adrenaline - in response to stress and exercise, increases heart rate
Secreted by adrenal cortex:
Cortisol - essential for adaptation to stress, mobilises glucose
anti-inflammatory actions (At high levels)
Aldosterone - maintains balance of Na/K in blood
H-P-A axis
What is the process of the secretion of cortisol?
1) Hypothalamus releases corticotropin releasing hormone (CRH) that acts on the anterior pituitary
2) This then releases corticotropin (ACTH) which acts on the adrenal medulla
3) The adrenal medulla then releases cortisol
4) High levels of cortisol inhibit release of corticotropin and corticotropin releasing hormone.
What is Addison’s disease
Deficiency of adrenocortical hormone - affects about 1- 50,000 people
Causes of Addison’s disease
~70% due to autoimmune destruction of adrenal cortex
Can be caused by infectious diseases (e.g TB)
Addison’s disease symptoms
Occurs in all age groups - both sexes equally
weight loss, muscle weakness, fatigue, low BP
often darkening of the skin and gums
Addison’s disease treatment
Replacement therapy with cortisol (and mineralocorticoid if needed)
What is Cushing’s syndrome?
Hypersecretion of cortisol
What causes Cushing’s syndrome?
Rapid pituitary ACTH secretion (=cushing’s disease)
Inappropriate ACTH secretion from tumour (pituitary or elsewhere)
Raised cortisol secretion from tumour in adrenal cortex
Cushing’s syndrome symptoms
Raised blood glucose levels => polyuria, polydipsia
Loss of muscle mass due to protein breakdown for gluconeogenesis
Deposition of new fat around abdoment, face, shouldners
Cardiovascular disease
Cushing’s syndrome treatment
Surgical removal of tumour
irradiation of tumour
inhibitors of steroid biosynthesis
(usually fatal within 5 years if untreated)