Endocrinology 5

oelomar's version from 2018-11-19 16:52


Question Answer
What is tertiary hyperparathyroidism?Tertiary hyperparathyroidism is a state of excessive secretion of PTH after a long period of secondary hyperparathyroidism and resulting in a high blood calcium level.
What is Trousseau’s sign of latent tetany and what does it indicate?Trousseau’s sign of latent tetany is a medical sign observed in hypocalcaemia. To elicit the sign, a blood pressure cuff is placed around the arm and inflated to a pressure greater than the systolic blood pressure and held in place for 3 minutes. This will occlude the brachial artery. In the absence of blood flow, the patient's hypocalcaemia and subsequent neuromuscular irritability will induce spasm of the muscles of the hand and forearm. The wrist and metacarpophalangeal joints flex.
What clinical investigations can be carried out to help diagnose hypoparathyroidism?Low serum calcium, low/absent serum PTH levels, low 25—hydroxy vitamin D serum level, parathyroid antibodies (present in idiopathic hypoparathyroidism), x-rays of metacarpals showing short 4th & 5th fingers (occurs in pseudohypoparathyroidism), low serum magnesium levels (hypomagnesaemia results in functional hypoparathyroidism).
How is hypoparathyroidism treated?Calcium supplements and calcitriol (vitamin D metabolite) or synthetic PTH.
What are the clinical features of hyperaldosteronism?The usual presentation is hypertension, hypernatraemia, and hypokalaemia. The few symptoms are non-specific; rarely muscle weakness, nocturia and tetany are seen.
What is Conn’s syndrome?Also known as primary hyperaldosteronism, Conn’s syndrome is excess aldosterone production by the adrenal glands resulting in low renin production from the kidneys.
What investigations are carried out to diagnose hyperaldosteronism?Plasma aldosterone:renin ratio (ARR) will be raised (this is a screening test as raised ARR alone does not confirm the diagnosis). Blood pressure is elevated, and there are high serum levels of sodium, and low serum levels of potassium. Once a diagnosis of hyperaldosteronism is established, differentiation of adenoma from hyperplasia involves adrenal CT or MRI.
How is primary hyperaldosteronism treated?An adenoma can be removed laparoscopically. Those with hyperplasia should be treated with the aldosterone antagonist spironolactone.
What is secondary hyperaldosteronism and what can cause it?Secondary hyperaldosteronism occurs as a result of excess renin (and hence angiotensin II) stimulation. One cause is a juxtaglomerular cell tumour. Another is renal artery stenosis.


Question Answer
What is a phaeochromocytoma?A neuroendocrine tumour of the medulla of the adrenal glands (90%) that secretes high amounts of catecholamines (10% occur elsewhere in the sympathetic chain). Most tumours release both noradrenaline and adrenaline. Large tumours and extra-adrenal tumours produce almost entirely norepinephrine.
How is a phaeochromocytoma diagnosed?Measurement of urinary catecholamines and metabolites (metanephrines (metabolites of adrenaline) are most sensitive and specific) is a useful screening test; normal levels on three 24-hour collections of metanephrines virtually exclude the diagnosis. CT/MRI can be used to help located the tumour.
What is multiple endocrine neoplasia (MEN)?MEN is a term which encompasses several distinct syndromes featuring tumours of endocrine glands. MEN syndromes are inherited as autosomal dominant disorders.
What neoplasias are associated with MEN 1?Also known as Wermer’s syndrome. Associated with the “3 P’s” – pituitary, parathyroid, pancreatic.
What neoplasias are associated with MEN 2A?Also known as Sipple’s syndrome. Associated with “2 P’s, 1 M” – medullary thyroid carcinoma (secretes calcitonin), phaeochromocytoma, parathyroid.
What neoplasias are associated with MEN 2B?“1 P, 2 M’s” – medullary thyroid carcinoma (secretes calcitonin), marfanoid habitus (constellation of symptoms including long limbs, arm span exceeding the height of the individual, crowded oral maxilla sometimes with a high arch in the palate, abnormally long and slender fingers and toes, and hypermobility of joints), phaeochromocytoma.
What is McCune-Albright syndrome?This is a genetic disorder of bones, skin pigmentation, and hormonal problems along with premature puberty. It is associated with hypersecretion of a number of endocrine glands at a young age.