Abstract
For the diagnosis of primary aldosteronism (PA), confirmatory testing is mandatory
and different function tests can be employed. There are, however, sparse data comparing
the fludrocortisone suppression test (FST) and the saline infusion test (SIT). Patients
with PA (n=90) or essential hypertension (n=65) were studied. They underwent one or
the other test or both of them. Using the DPC Siemens aldosterone radioimmunoassay,
we found that the SIT led to a stronger suppression of aldosterone than the FST. Post-test
aldosterone-to-renin ratios (ARRs) and the percentage of suppression of aldosterone
serum concentrations performed worse. The same results were observed in patients who
underwent both FST and SIT. Some patients had divergent results in both tests. For
the SIT, a lower cutoff value should be used than for the FST for the adequate identification
of patients with unilateral PA. Long-term prospective studies are needed to address
the question at what cutoff values patients benefit from subtype differentiation of
PA. We discuss here possible explanations for divergent results obtained with both
tests.
Key words
aldosterone - adrenal - fludrocortisones - hypertension
