primary hyperaldosteronism

Question 1

definition of primary hyperaldosteronism

Answer 1

charactersied by autonomous aldosterone overproduction form the adrenal gland with subsequent supression of plasma renin activity

independant of the RAAS

consider if HTN, hypokalaemia or alkalosis in someone not on a diuretic

Question 2

aetiology of primary hyperaldosteronism

Answer 2

secondary to adrenal adenoma - Conn’s syndrome (70%) - mutations in K channels

hyperplasia of the adrenal cortex (30%)

rare: glucocorticoid suppressible hyperaldosteronism (1-3%) - ACTH regulatory element of the 11B-hydroxylase gene fuses to the aldosterone synthasis gene = increased aldosterone production and bringing it under control of ACTH

aldosterone producing adrenal carcinoma

Question 3

pathophysiology of primary hyperaldosteronism

Answer 3

increased Na and water retention = HTN

increase renal K loss = hypokalaemia

supression of renin because of NaCl retention

Question 4

epidemiology of primary hyperaldosteronism

Answer 4

prev in hypertensive patients is 1-2%

aldosterone producing adenoma occurs more in women and <50yrs

bilateral adreanl hyperplasia more in men and older

Question 5

symptoms of primary hyperaldosteronism

Answer 5

asymptomatic until picked up on routine bloods

symptoms of hypokalaemia:

• muscle weakness
• polyuria
• polydipsia
• polydipsia - nephrogenic diabetes insipidus secondary to hypokalaemia
• parasthesia
• tetany
• cramps

Question 6

signs of primary hyperaldosteronism

Answer 6

HTN

complications of HTN ie retinopathy

Question 7

screening investigations for primary hyperaldosteronism

Answer 7

UE, renin and aldosterone

low serum K (<4mmol/L), serum na normal - because parallel rise inwater content

inappropriately high urine K

increased plasma aldosterone conc:plasma renin activity ratio after stopping anti-HTN (spirinolactone for 6wk, others for 2wk)

• if anti-hypertensive therapy is required - a blocker can be used
• hypokalaemia should be corrected before test

genetic testing available for GSH - suspect if FH of early HTN

Question 8

classes of confirmatory test for primary hyperaldosteronism

Answer 8

salt loading

determining cause:

• postural test
• CT or MRI abdo
• bilateral adrenal vein catheterisation
• radio-labelled cholesterol scanning

Question 9

salt loading for primary hyperaldosteronism

Answer 9

failure of aldosterone suppression follwing Na load (oral or IV 0.9% NaCl)

confirms primary hyperaldosteronism

Question 10

postural test for primery hyperaldosteronism

Answer 10

plasma aldosterone, renin activity and cortisol are measured with patient recumbent at 8am

test repeated after 4hr of being upright ie 12noon

in adenomas which are ACTH sensitive - aldosterone secretion decrease from 8 - 12

in bilateral adrenal hyperplasia, adrenals respond to standing pressure by increasing renin and thus increase aldosterone secretion

20% false -ve rate

Question 11

CT or MRI abdo for primary hyperaldosteronism

Answer 11

visualise the adrenals

Question 12

bilateral adrenal vein catheterisation for primary hyperaldosteronism

Answer 12

allow distinction between conn’s and bilateral adrenal hyperplasia by measuring adrenal vein in aldosterone levels

Question 13

radiolabelled cholesterol scanning for primary hyperaldosteronism

Answer 13

unilateral uptake in adrenal adenomas

bilateral uptake in bilateral adrenal hyperplasia

Question 14

management of bilateral adrenal hyperplasia

Answer 14

spirinolactone - an aldosterone receptor antagonist

change to eplerenone if spirinolactone SE are intolerable (gynaecomastia, impotence, menstrual irregularities, muscle cramps and GI upset)

amiloride - K sparing diuretic

monitor serum K and creatinine and BP

ACEi and CCB may need to be added

take 4-8wks for HTN to respond to treatment

Question 15

treatment of aldosterone producing adenomas

Answer 15

adrenalectomy

laproscopic surgery associated with reduced post-op morbidity, hospital stay and expense compared to open laparotomy

spirinolactone 25-100mg/24hr PO, for 4wk pre-op controls BP and K

Question 16

treatment of adrenal carcinoma

Answer 16

surgery and postop mititane (selectively inhibits the activity of the adrenal cortex) - poor prognosis

GSH is treated with dexamethasone (0.25mg in morning, 0.5mg at night) - normalises biochem but not necessarily HTN, if so - use spirinolactone

Question 17

complications of primary hyperaldosteronism

Answer 17

same as for HTN

Question 18

prognosis of primary hyperaldosteronism

Answer 18

surgery may cure HTN in 50%

or make it mroe amenable to anti-HTN therapy in those who are not cured - usually elderly or people with long standing HTN