AN 18-YEAR-OLD white man with neurofibromatosis (NF) presented with intermittent hypertension. His medical history included a plexiform neurofibroma of the left eye and spinal fusion for xyphoscoliosis. His physical examination revealed a blood pressure of 170/110 mm Hg, facial asymmetry with proptosis of the left eye, Lisch nodules in the right eye, normal cardiopulmonary function, and a soft abdomen without hepatosplenomegaly or masses. No bruits were present. His skin showed multiple café au lait spots, axillary freckling, and a neurofibroma on his left ankle.
Results of a laboratory evaluation, including complete blood cell count, routine blood chemistry studies, and urinalysis, were normal. A 24-hour evaluation of a urine specimen for vanillylmandelic acid and catecholamine levels yielded normal results. A renal nucleotide scan and flow with captopril showed slightly decreased perfusion to the right kidney with decreased excretion and radionuclide retention in the calyx of the upper pole. Postcaptopril renin levels