Figure 7. Vitamin C secretion by human adrenal glands.

Vitamin C concentrations were measured in the adrenal and peripheral veins of 26 patients with primary hyperaldosteronism. Under radiographic guidance, catheters were placed in both adrenal veins, and blood samples were taken after stimulation with adrenocorticotrophic hormone (ACTH). Vitamin C concentrations in each of the adrenal (n = 47) and peripheral (n = 26) veins sampled are shown. In 5 patients, blood samples were obtained from only one adrenal vein because of unusual venous anatomy or difficulties with adrenal vein catheterization. In the adrenal veins, peak vitamin C concentrations (Mean ± SD: 176 ± 71 µmol/L) were reached between 1 and 4 min, and were significantly (P < 0.0001, paired t test) higher than corresponding peripheral plasma vitamin C concentrations (35 ± 15 µmol/L). In patients in whom adrenal vein vitamin C concentration could be measured in only one adrenal gland, that single value was used in the calculation. In patients in whom both adrenals were successfully sampled, the mean of the two adrenal vein vitamin C concentrations was used for calculation, but all values are shown. Modified and reproduced from (Padayatty et al., 2007), with permission from American Journal of Clinical Nutrition.