Endocrinology Revision Flashcards
What is the most common drug causing gynaecomastia?
Spironolactone
How can goserelin cause gynaecomastia?
GnRH agonist
In normal physiology, the pulsatile release of GnRH stimulates testosterone production.
When goserelin is given long-term in a non-pulsatile manner, this disrupts the endogenous feedback loops controlling testosterone production, and results in hypoandrogenism.
This in turn causes the development of gynaecomastia.
What is Conn’s syndrome?
1ary hyperaldosteronism
Most common cause of 1ary hyperaldosteronism?
Bilateral idiopathic adrenal hyperplasia
Features of 1ary hyperaldosteronism?
1) HTN
2) Hypokalaemia
3) Metabolic alkalosis
How can hypokalaemia present?
Muscle weakness
1st line investigation in suspected Conn’s?
Plasma aldosterone/renin ratio
What will a plasma aldosterone/renin ratio show in Conn’s?
HIGH aldosterone levels alongside LOW renin levels (negative feedback due to sodium retention from aldosterone)
What is next investigation following plasma aldosterone/renin ratio in Conn’s?
High resolution CT & adrenal vein sampling
These are used to differentiate between unilateral and bilateral sources of aldosterone excess
Mx of adrenal adenoma causing Conn;s?
surgery (laparoscopic adrenalectomy)
Mx of bilateral adrenocortical hyperplasia causing Conn’s?
Aldosterone antagonist e.g. spironolactone
What is seen in sick euthyroid?
TSH low or normal
T3 & T4 low
What is the most important modifiable risk factor for the development of thyroid eye disease?
Smoking
What is subacute thyroiditis (De Quervain’s thyroiditis)?
Typically presents with hyperthyroidism.
Thought to follow viral infection.
What are the 4 phases of hyperthyroidism?
phase 1 (lasts 3-6 weeks): hyperthyroidism, painful goitre, raised ESR
phase 2 (1-3 weeks): euthyroid
phase 3 (weeks - months): hypothyroidism
phase 4: thyroid structure and function goes back to normal
What is seen on thyroid scintigraphy in De Quervain’s thyroiditis?
globally reduced uptake of iodine-131
Does Cushing’s cause a metabolic acidosis or alkalosis?
Alkalosis –> bicarbonate resorption is increased in the tubules with potassium depletion
Mechanism of labetalol?
Both alpha AND beta blocking qualities
Definitive mx of primary hyperparathyroidism?
total parathyroidectomy (NOT subtotal)
How often must insulin-dependent diabetics check their blood glucose whilst driving?
Every 2 hours
1st line insulin regime for newly diagnosed adults with type 1 diabetes?
basal-bolus using twice-daily insulin detemir
What conversion is impaired in CAH caused by 21-hydroxylase deficiency?
Impairs the conversion of 17-hydroxyprogesterone to 11-deoxycortisol, leading to cortisol deficiency and excess androgen production
Therefore there will be increased plasma 17-hydroxyprogesterone levels.
What is required for both PTH secretion & its action on target tissues?
Magnesium
How can hypomagnesaemia affect calcium?
Hypomagnesaemia may both cause hypocalcaemia and render patients unresponsive to treatment with calcium and vitamin D supplementation.