Direct evaluation of adrenocortical function by measurement of adrenal percent uptake of 131I-6β-iodomethyl-19-norcholesterol using single photon emission computed tomography

In 55 patients (110 adrenal glands) with suspected adrenocortical abnormalities, I assessed the clinical usefulness of adrenal percent uptake of 131I-6β-iodomethyl-19-norcholesterol (NCL-6-131I) by single photon emission computed tomography (SPECT). The percent uptake of NCL-6-131I in 6 hyperfunctioning glands of patients with the final diagnosis of Cushing's syndrome (2.62±1.13(SD)%) was significantly (p<0.01) higher than that in 10 glands of patients with the final diagnosis of adenoma of primary aldosteronism (1.16±0.09(SD)%). Moreover, the percent uptake of NCL-6-131I in adrenal glands with hyperfunctioning lesions was significantly (p<0.01) higher than those in 10 contralateral normal glands of primary aldosteronism (0.55±0.23(SD)%), 30 right glands (0.57±0.24(SD)%) and 30 left glands (0.53±0.22(SD)%) of essential hypertension with normally functioning adrenal cortices. The adrenal percent uptake of NCL-6-131I in 24 glands with hypofunctioning adrenal cortices, including 4 glands suppressed by adenomas of Cushing's syndrome, was below the detectable limit. The data presented above show that the adrenocortical function can be evaluated directly based on measurement of adrenal percent uptake of NCL-6-131I using SPECT. (author)