AJP - Endocrinology and Metabolism, Vol 260, Issue 2 E243-E246, Copyright © 1991 by American Physiological Society
Plasma chromogranin A as a marker of sympathochromaffin activity in humans
P. E. Cryer, J. Wortsman, S. D. Shah, R. M. Nowak and L. J. Deftos
Division of Endocrinology, Washington University School of Medicine, St. Louis, Missouri 63110.
The extent to which the sympathochromaffin system compared with other
endocrine/neuroendocrine tissues contributes to the plasma chromogranin A
pool has not been defined. To test the hypothesis that the
sympathochromaffin system is the major source of circulating chromogranin A
only when that system is activated markedly, we measured chromogranin A
concentrations in 200 human plasma samples known to have a broad range of
norepinephrine and epinephrine concentrations, reflecting therefore a broad
range of sympathochromaffin activity at the time of sampling. Plasma
chromogranin A and norepinephrine concentrations were highly correlated
when the sympathochromaffin system was activated markedly (cardiac arrest
samples, n = 13, r = 0.8392, P less than 0.0005) and when there was release
of large amounts of norepinephrine from tumors (pheochromocytoma samples, n
= 17, r = 0.8132, P less than 0.001). However, when the sympathochromaffin
system was activated less markedly, resulting in plasma catecholamine
concentrations that spanned the physiological and lower pathophysiological
range (nonpheochromocytoma noncardiac arrest samples, n = 170),
correlations between plasma chromogranin A and norepinephrine (r = 0.2877,
P less than 0.0001) and epinephrine (r = 0.3814, P less than 0.0001) levels
were relatively weak, although still statistically significant. Thus, at
basal through moderate stress levels, norepinephrine and epinephrine
concentrations accounted for only approximately 10-15% of the variance in
plasma chromogranin A levels. We conclude that, although plasma
chromogranin A concentrations are a valid marker of sympathochromaffin
activity in humans, they are not a sensitive marker under physiological
conditions.
