Patient selection: primary aldosteronism
Initial testing: abdominal CT to visualize both adrenal glands
Subtyping by CT was concordant with AVS in 56% of patients with bilateral adrenal tumors, 38% of patients with unilateral adrenal tumors and 89% of patients without adrenal tumors.
Rules:
(1) If a patient has an adrenal tumor on abdominal CT, then perform adrenal vein sampling.
(2) If a patient does not have an adrenal tumor on abdominal CT, then use score to determine if adrenal vein sampling is appropriate.
Parameters in a patient without adrenal tumor on CT:
(1) sex
(2) serum potassium in mmol/L
(3) aldosterone to renin ratio (ARR)
aldosterone to renin activity ratio =
= (aldosterone in pg/mL) / (renin activity in ng/mL per hour)
|
Parameter
|
Finding
|
Points
|
|
sex
|
female
|
1
|
|
|
male
|
0
|
|
serum potassium
|
< 3.8 mmol/L
|
0
|
|
|
>= 3.8 mmol/L
|
1
|
|
ARR
|
<= 550
|
1
|
|
|
> 550
|
0
|
total score =
= SUM(points for all 3 parameters)
Interpretation:
• minimum score: 0
• maximum score: 3
• The higher the score the greater the chance of bilateral disease.
• A patient with a score of 3 probably has bilateral disease and does not need adrenal vein sampling.
|
Score
|
Sensitivity for Bilateral
|
Specificity for Bilateral
|
|
2
|
74%
|
75%
|
|
3
|
29%
|
96%
|
Performance:
• The area under the ROC curve is 0.80.
