Internal Medicine

0521779407-14 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:16

Mineralocorticoid Disorders 987

➣Mineralocorticoid excess: spontaneous or easily provoked

hypokalemia, metabolic alkalosis, hypernatremia (mild), dilu-

tional anemia, hypomagnasemia, kaliuresis

➣Mineralocorticoid deficiency: hyperkalemia, hyperchloremic

nonanion gap acidosis (type IV RTA)

■Basic urine studies:

➣24-h urine potassium

■Specific Diagnostic Tests

➣Mineralocorticoid excess:

Supine plasma renin activity (PRA), aldosterone level: ratio of

aldosterone/PRA >30 with elevated plasma aldosterone con-

centration suggestive of primary hyperaldosteronism

24-h urine for aldosterone, creatinine

Normal saline infusion 2.0 L over 4 h with serum aldoster-

one pre/post: aldosterone >10 ng/dL consistent with primary

hyperaldosteronism

24-h urine for aldosterone, creatinine while off ACE inhibitors,

beta-blockers for 1–2 wk, on high salt intake: aldosterone excre-

tion >15 mcg/d consistent with primary hyperaldosteronism

18-OH-corticosterone: usually increased in adenoma

➣Mineralocorticoid deficiency:

Serum PRA, aldosterone levels pre/post furosemide or 3-h

upright

Serum aldosterone 60 min post-Cosyntropin

Imaging

■Mineralocorticoid excess: CT/MRI of adrenals, radionuclide scintig-

raphy (not usually needed)

■Mineralocorticoid deficiency: none

Other Tests

■Mineralocorticoid excess: adrenal vein sampling of aldosterone pre/

post-Cosyntropin, serum aldosterone post-dexamethasone

differential diagnosis

■Mineralocorticoid excess:

➣Primary hyperaldosteronism: adenoma, hyperplasia; glucocor-

ticoid-remediable hyperaldosteronism; licorice (glycyrrhetinic

acid) ingestion

➣Secondary hyperaldosteronism

➣Low renin hypertension

➣Liddle syndrome