Hyperaldosteronism may be either primary or secondary.
Primary disease (Conn's syndrome) is due to excess production of aldosterone, most commonly due to an adrenal adenoma. This results in excess sodium and water retention with loss of potassium and hydrogen ions. Patients therefore become hypertensive with hypokalaemic alkalosis. In this situation, the juxtaglomerular apparatus is not stimulated and renin levels are therefore low.
Secondary disease is due to impaired renal perfusion most commonly associated with renal vascular disease or malignant hypertension. This results in excess production of renin from the juxta-glomerular apparatus, ultimately causing excess aldosterone production. Renin levels are therefore high.
The diagnosis of Conn's syndrome rests on having a high index of suspicion. The diagnosis may not be obvious because many patients with hypertension are prescribed diuretics which cause hypokalaemia. Initially, hypertension and hypokalaemia may therefore simply be mistaken for effects of therapy. Renin levels may aid in making the diagnosis. A CT scan showing a small adrenal mass in a patient suspected of having Conn's syndrome, may aid in confirming the diagnosis.
An adenoma may be detected by iodo-cholesterol scanning. Carcinomata tend not to show with isotope scans. Only two cases of ectopic aldosterone producing adenomas have been described, one in the kidney and one in the ovary. Bilateral adenomata are exceedingly rare.
Patients may be controlled medically, initially by spironolactone. If the patient is elderly and the dose is small, this may be the preferred treatment. Otherwise it is most cost-effective to treat surgically.
In patients who are on a large dose or who experience side effects of the drug, such as impotence, gynaecomastia, hypotension and weakness due to hypokalaemia, surgery is indicated. Since these tumours are normally unilateral and small, laparoscopic adrenalectomy is the treatment of choice. Total adrenalectomy is normally performed rather than simple extirpation of the tumour from the gland.
Since there is no glucocorticoid suppression of the contralateral gland, post-operative steroids are not necessary. However, the occasional patient may experience problems with mineralocorticoid suppression of the opposite gland and this may not recover instantly. Weight loss, hyperkalaemia and hypotension within 1 week of surgery indicate a need for mineralocorticoid replacement by fludrocortisone. This rarely requires to continue beyond 1 month.
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