Patient Preparation:
With the patient supine, a catheter is introduced into the inferior vena cava. Specimens are collected simultaneously from both adrenal veins and from the inferior vena cava.
Test performed: Each sample is tested for aldosterone and for cortisol.
aldosterone-to-cortisol ratio =
= (aldosterone) / (cortisol)
NOTE: Need to check units. Aldosterone conventional units are ng/dL; for cortisol µg/dL.
Interpretation
In a unilateral adenoma, the adrenal vein from the affected side will show an increase in aldosterone and the aldosterone-cortisol ratio relative to the inferior vena cava. The aldosterone in the adrenal vein of the affected side will usually be at least 5 times greater than that seen on the uninvolved side
• in a unilateral adenoma, the adrenal vein from the unaffected side will show a markedly reduced aldosterone and both the aldosterone and aldosterone-cortisol ratio will be less than in the inferior vena cava
• in patients with an adenoma, aldosterone levels decrease when the patient goes from the supine to upright position, whereas normal persons show the opposite (an increase in aldosterone is seen when going from the supine to upright position
In bilateral adrenal hyperplasia or bilateral adenomas, the aldosterone-cortisol ratios will be approximately equal in both adrenal veins; these both will be greater than that seen in the inferior vena cava.
