Lec4 Adrenal causes of hypertension Flashcards
What is the location of the adrenal glands?
Superior pole of the kidneys, retroperitoneal - around T12
How big are the adrenal glands?
1.5 inches in height x 3 inches in length
What do the adrenals looks like on a CT scan (cross section through it)?
Inverted Y shape
Name the layers of the adrenal glands
Zona glomerulosa
Zona Fasciculata
Zona Reticularis
Medulla
What do each of the layers produce?
G - produces Aldosterone - swaps sodium for potassium
F - produces Cortisol - elevates blood glucose
R- produces adrenal androgens - sex hormones
What are the three adrenal causes of hypertension?
- Primary Hyperaldosteronism
- Phaeochromocytoma
- Some forms of Congenital Adrenal Hyperplasia
Which layer in the adrenal gland contributes to primary hyperaldosteronism?
Zona Glomerulosa - because it produces aldosterone
What can cause the zone glomerulosa to produce excess aldosterone?
Adenoma of the ZG - a single, enlarged node producing excess aldosterone
Hyperplasia - enlarged tissue
Rare genetic causes
How does excess aldosterone produced in the zone glomerulosa cause hypertension?
Excess aldosterone causes excess sodium to be reabsorbed in the kidney tubule and so water also follows and is reabsorbed, which leads to HYPERTENSION
In which layer of the adrenal gland does a phaeochromocytoma develop?
Adrenal medulla
What is a phaeochromocytoma (phaeo)?
A tumour of the adrenal medulla which results in high levels of noradrenaline and adrenaline
What is Congenital Adrenal Hyperplasia?
It is an uncommon enzyme defect
leads to a build up of aldosterone, causing hypertension
What kind of molecule is aldosterone?
Mineralocorticosteroid
Describe the pathway for aldosterone secretion
When the kidneys are under perfused this is sensed by baroreceptors in the renal artery
The kidney responds by producing RENIN
Renin catalyses the reaction which turns ANGIOTENSINOGEN into ANGIOTENSIN I
ANGIOTENSIN CONVERTING ENZYME - ACE - catalyses conversion of ANGIOTENSIN I into ANGIOTENSIN II
Angiotensin II causes production of ALDOSTERONE which acts on the kidney and causes water to be reabsorbed
This INCREASES BLOOD PRESSURE
What is Conn’s Syndrome?
A condition in which there is excess aldosterone
Why is it important to distinguish between primary hyperaldosteronism (PA) /Conn’s syndrome and essential hypertension?
Because Conn’s syndrome is a potentially curable cause of high blood pressure
What type of patients would you screen for PA?
- Hypokalaemic patients - this might be due to high aldosterone
- Resistant hypertension patients - on 3 hypotensive drugs
- Young people - there is much more likely to be an underlying cause for their hypertension
Why are patients with PA worse off than patients who just have straight forward hypertension?
Because PA patients have more vascular and renal pathology than a patient with essential hypertension with the same blood pressure
What is the initial screening test for PA?
Suppressed renin with normal/high aldosterone indicates PA
What is the confirmatory test for PA?
Oral or IV Na+ suppression test
If there is a high sodium, you expect the aldosterone to be low because there is no need for more production of aldosterone when sodium is high
If there is normal to high aldosterone at high levels of sodium then there is inappropriate aldosterone production
What are the tests for specific aetiology of PA? i.e. secreting adenoma or bilateral hyperplasia
- Adrenal CT scan
- Adrenal venous sampling - to see if the aldo secretion is uni/bilateral
- Metomidate PET CT
Older adults often have nodules in their adrenal glands which are harmless. True or False?
True
What forms of treatment are there for Unilateral adenoma in Primary Hyperaldosteronism?
Laparascopic adrenalectomy Medical treatment (sometimes)
What is the treatment for Bilateral Hyperplasia in PA?
Medical treatment with ALDOSTERONE ANTAGONISTS
e.g. Spironolactone and Eplerinone
