title: Plasma chromogranin A as a marker of sympathochromaffin activity in humans.
abstract: 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.
authors.affiliation: Division of Endocrinology, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: P E
authors.initials: PE
authors.lastname: Cryer
authors.forename: J
authors.initials: J
authors.lastname: Wortsman
authors.forename: S D
authors.initials: SD
authors.lastname: Shah
authors.forename: R M
authors.initials: RM
authors.lastname: Nowak
authors.forename: L J
authors.initials: LJ
authors.lastname: Deftos
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000097:blood*; D000313:Adrenal Medulla / Q000294:innervation / Q000502:physiology*; D015415:Biomarkers; D053379:Chromogranin A; D002864:Chromogranins / Q000097:blood*; D004837:Epinephrine / Q000097:blood*; D006323:Heart Arrest / Q000097:blood*; D006801:Humans; D009638:Norepinephrine / Q000097:blood*; D010673:Pheochromocytoma / Q000097:blood*; D011863:Radioimmunoassay; D012016:Reference Values; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D015415:Biomarkers; C506150:CHGA protein, human; D053379:Chromogranin A; D002864:Chromogranins; D009638:Norepinephrine; D004837:Epinephrine