Normokalemic hyperaldosteronism in patients with resistant hypertension.
BACKGROUND
Primary aldosteronism is a common cause of non-renal secondary hypertension. A correct diagnosis results in curing the hypertension or targeting appropriate pharmacotherapy. In patients with low renin resistant hypertension (after treatment with three or more different anti-hypertensive drugs the blood pressure remains above 140/90 mmHg), screening for aldosteronism is mandatory.


OBJECTIVE
To demonstrate that normal blood levels of potassium in resistant hypertensive patients do not exclude the possible presence of hyperaldosteronism, and to suggest the use of the plasma aldosterone concentration (ng/dl)/plasma renin activity (ng/ml/hour) ratio in screening for hyperaldosteronism.


METHODS
Blood tests, suppression and stimulation tests (2 L normal saline i.v./4 hours and 20 mg furosemide i.v. for 60 minutes in a standing position) were systematically performed in 20 low renin normokalemic resistant hypertensive patients. None had renal disorders, known endocrine abnormalities or heart failure. They did not receive anti-hypertensive drugs affecting PAC or PRA. Basal PRA and PAC were measured twice: PAC after saline infusion and PAC/PRA after stimulation.


RESULTS
PAC/PRA above 50 was used to denote hyperaldosteronism. Serum K was 4 +/- 0.07 mM/L, PAC 22.8 +/- 1.8 ng/dl, PRA 0.13 +/- 0.02 ng/ml/hour, PAC/PRA 190 +/- 22 (above 100 in 17). After suppression PAC decreased from 25 +/- 1.8 to 11 +/- 1 ng/dl (normal < 5 ng/dl). Stimulation did not affect PRA and PAC/PRA. Abdominal computed tomography scan revealed normal adrenal glands in 15 patients. Spironolactone (116 +/- 60 mg/day) normalized blood pressure in all patients; it was used as a single therapy in 8, and in association with only one anti-hypertensive drug in the remaining 12 patients. In one patient the treatment was discontinued due to the presence of hyperkalemia.


CONCLUSIONS
Low renin resistant hypertension associated with normokalemia may be due to hyperaldosteronism. Normal aldosterone levels in the basal condition do not exclude the possibility of hyperaldosteronism. Using a PAC/PRA ratio above 50 as a screening test can aid the physician in deciding when to perform dynamic tests, thus increasing the sensitivity of the diagnosis of hyperaldosteronism. CT scan is frequently normal. Targeted pharmacotherapy leads to a normalization of blood values.
Benchetrit
Sydney
S
Department of Nephrology, Meir Hospital, Sapir Medical Center, Kfar Saba, Israel. drsidney@inter.net.il
Bernheim
Jacques
J
Podjarny
Eduardo
E
D000328:Adult; D000368:Aged; D000450:Aldosterone / Q000097:blood*; D000704:Analysis of Variance; D000959:Antihypertensive Agents / Q000627:therapeutic use; D003404:Creatinine / Q000097:blood; D005260:Female; D006801:Humans; D006929:Hyperaldosteronism / Q000097:blood* / Q000150:complications* / Q000188:drug therapy; D006973:Hypertension / Q000097:blood* / Q000188:drug therapy / Q000209:etiology*; D007008:Hypokalemia / Q000097:blood* / Q000150:complications*; D008297:Male; D008875:Middle Aged; D000451:Mineralocorticoid Receptor Antagonists / Q000627:therapeutic use; D011188:Potassium / Q000097:blood*; D012083:Renin / Q000097:blood*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013148:Spironolactone / Q000627:therapeutic use
D000959:Antihypertensive Agents; D000451:Mineralocorticoid Receptor Antagonists; D013148:Spironolactone; D000450:Aldosterone; D003404:Creatinine; D012083:Renin; D011188:Potassium