Chromogranin A in children with neuroblastoma. Serum concentration parallels disease stage and predicts survival.

Chromogranin A is an acidic protein costored and coreleased with catecholamines from storage vesicles. Its serum concentration is elevated in patients with peptide-producing endocrine neoplasia. We measured serum chromogranin A at the time of diagnosis in 34 children with all stages of neuroblastoma. With a sensitivity of 91% and specificity of 100%, serum chromogranin A emerged as a useful diagnostic tool for neuroblastoma, comparable to or better than other measurements such as neuron-specific enolase, ferritin, or dopamine-beta-hydroxylase. Mean serum chromogranin A correlated with disease stage (r = 0.76, P less than 0.01). The relationship of prognosis (progression-free survival) to baseline serum chromogranin A, age, and disease stage was determined in 34 patients at risk for relapse, with a median followup period of 18 mo (range, 1-48 mo). The survival rate for patients with lower serum chromogranin A levels (less than 190 ng/ml at the time of diagnosis) was 69%, whereas it was 30% for those with higher chromogranin A levels (P less than 0.05). Furthermore, when subjects were additionally stratified by either age or stage, chromogranin A was an effective prognostic tool in patients who either were older than 1 yr (P less than 0.005) or had more advanced disease (stage III or IV; P less than 0.05). We conclude that serum chromogranin A in neuroblastoma is (a) a valuable (sensitive and specific) diagnostic tool, (b) a correlate of tumor burden, and (c) a useful predictor of survival.

Chromogranin A. Storage and release in hypertension.

The chromogranins/secretogranins are a family of acidic, soluble proteins with widespread neuroendocrine distribution in secretory vesicles. Although the precise function of the chromogranins remains elusive, knowledge of their structure, distribution, and potential intracellular and extracellular roles, especially that of chromogranin A, has greatly expanded during recent years. Chromogranin A is coreleased with catecholamines by exocytosis from vesicles in the adrenal medulla and sympathetic nerve endings. Thus, measurement of its circulating concentration by radioimmunoassay may be a useful probe of exocytotic sympathoadrenal activity in humans, under both physiological and pathological conditions. Here, we explore the storage, structure, and function of chromogranin A, and parameters that influence its circulating levels. We have also measured plasma chromogranin A concentrations in different groups of patients with hypertension, including those with pheochromocytoma.

Chromogranin A storage and secretion: sensitivity and specificity for the diagnosis of pheochromocytoma.

Chromogranin A, co-stored and co-released with catecholamines from adrenal medullary and sympathetic neuronal vesicles, is elevated in the plasma of patients with pheochromocytoma. The usefulness of the hormone in the differential diagnosis of hypertension is examined. An elevated level of chromogranin A had comparable diagnostic sensitivity (83%, 24/29) to, but greater diagnostic specificity (96%, 86/90) than the level of plasma catecholamines when subjects with pheochromocytoma (n = 29) were evaluated in comparison to several reference groups, including normotensive controls (n = 49), subjects with essential hypertension (n = 28), subjects with renovascular hypertension (n = 5), and subjects with primary aldosteronism (n = 3). Subjects with signs or symptoms suggesting pheochromocytoma, but in whom the diagnosis was ultimately ruled out (n = 5) had normal plasma levels of chromogranin A. A modest rise in chromogranin A in those with essential hypertension, and correlation of chromogranin A with diastolic blood pressure in normotensive patients and patients with essential hypertension did not impair the diagnostic usefulness of chromogranin A for pheochromocytoma. Renal failure was associated with an elevated plasma chromogranin A independently of blood pressure. Plasma chromogranin A correlated with tumor mass, tumor chromogranin A content, tumor norepinephrine content, and urinary vanillylmandelic acid excretion; it did not correlate with plasma or urinary catecholamines, nor with blood pressure in patients with pheochromocytoma. Plasma chromogranin A levels did not differ in subjects with pheochromocytoma when stratified by age, sex, tumor location, or tumor pathology. Several drugs used in the diagnosis or treatment of pheochromocytoma (clonidine, metoprolol, phentolamine, and tyramine) had little effect on plasma chromogranin A concentration. Within the pheochromocytoma, chromogranin A was localized along with catecholamines to the soluble core of chromaffin granules, where it accounted for 18 +/- 5% of vesicle soluble protein. We conclude that 1) chromogranin A emerges along with catecholamines from pheochromocytoma chromaffin granules; 2) plasma chromogranin A is a sensitive and specific diagnostic tool in evaluation of actual or suspected pheochromocytoma; 3) plasma chromogranin A predicts pheochromocytoma tumor size and overall catecholamine production; and 4) drugs commonly employed in the diagnosis or treatment of pheochromocytoma have little effect on plasma chromogranin A level, preserving the usefulness of chromogranin A in evaluating pheochromocytoma. Thus, measurement of chromogranin A provides a useful adjunct to the diagnosis of pheochromocytoma.

Chromogranin A in familial pheochromocytoma: diagnostic screening value, prediction of tumor mass, and post-resection kinetics indicating two-compartment distribution.

PURPOSE: Chromogranin A, co-released with catecholamines from the adrenal medullary and sympathetic neuronal vesicles, is elevated in plasma from patients with pheochromocytoma. We assessed its diagnostic screening value, its plasma level in correlation with tumor mass, and its disposition kinetics in familial pheochromocytoma and sporadic pheochromocytoma. PATIENTS AND METHODS: The sensitivity and specificity of chromogranin A's diagnostic value for pheochromocytoma were established through one kindred with familial pheochromocytoma associated with von Hippel-Lindau syndrome (13 available members) and in seven subjects with sporadic pheochromocytoma. Serial postoperative plasma samples were also obtained (5 minutes to 4 days) from eight subjects with pheochromocytoma in order to study chromogranin A post-resection kinetics. Chromogranin A was measured by radioimmunoassay based on purified pheochromocytoma chromogranin A. RESULTS: In this kindred, elevations of chromogranin A (greater than 52 ng/mL) were sensitive (83%, five of six) and specific (100%, 10 of 10) in detecting familial pheochromocytoma; these diagnostic values comparable to those achieved by conventional evaluations for pheochromocytoma, such as urinary catecholamines, urinary catecholamine metabolites or imaging methods. Elevated levels of plasma chromogranin A specifically indicated pheochromocytoma, rather than von Hippel-Lindau syndrome gene carrier status. In 13 preoperative subjects with either familial or sporadic pheochromocytoma, plasma chromogranin A concentration predicted tumor size (r = 0.81, p less than 0.01). The change in chromogranin A plasma concentration after pheochromocytoma resection best fit a two-compartment model, with an initial rapid half-life time of 16 minutes, followed by a longer half-life time of 520 minutes. The model also predicted a 23.8:1 compartmental ratio of extravascular/intravascular chromogranin A, suggesting substantial tissue sequestration or binding of chromogranin A. CONCLUSIONS: (1) Plasma chromogranin A is a valuable (sensitive and specific) diagnostic tool in detecting both familial and sporadic pheochromocytoma. (2) The concentration of plasma chromogranin A predicts the size of the pheochromocytoma. (3) Chromogranin A post-resection kinetics suggest extravascular sequestration of chromogranin A.

Chromogranin A in uremia: progressive retention of immunoreactive fragments.

Chromogranin A is a soluble protein that is stored and released with catecholamines from their secretory vesicles. Its measurement is a probe of exocytotic sympathoadrenal activity, and in plasma it may also be a useful tool in the diagnosis of peptide producing endocrine neoplasms. Because we have found that chromogranin A is elevated in secondary (uremic) hyperparathyroidism, we systematically investigated the influence of renal dysfunction and its attendant hyperparathyroidism on chromogranin A in several subject groups: normal controls (serum creatinine less than or equal to 1.2 mg/dl), nonazotemic renal transplant recipients, nonazotemic subjects with glomerular disease (serum creatinine between 1.2 and 2 mg/dl), mid-range renal disease subjects (serum creatinine between 2 and 7.5 mg/dl), and end-stage renal disease subjects (serum creatinine greater than 7.5 mg/dl). Plasma chromogranin A rose with deterioration of renal function, and the rise was independent of etiologic diagnosis, blood pressure, or indices of sympathoadrenal activity or hyperparathyroidism. Size fractionation of uremic plasma by gel filtration, and immunoextraction by region-specific anti-chromogranin A (anti-N-terminal, anti-C-terminal, and anti-mid-molecule) antibodies suggested that chromogranin A immunoreactivity circulates in uremia as lower molecular weight fragments of the parent chromogranin A molecule, with mid-molecule fragments the major constituent. This immunoreactivity is only minimally removed by peritoneal dialysis and is not at all hemodialyzable. The uremia-dose-dependent accumulation of chromogranin A immunoreactive fragments in renal failure suggests that the kidney is a major site of disposition or removal of the immunoreactivity. Furthermore, lack of detectable chromogranin A immunoreactivity in normal subjects' urine suggests that the immunoreactivity is destroyed as it is removed by the kidney. We conclude that plasma chromogranin A increases in proportion to degree of renal insufficiency and that renal function must therefore be controlled when using plasma chromogranin A in the investigation of amine or peptide hormone storage and release.

Circulating chromogranin A as a diagnostic tool in clinical chemistry.

Chromogranin A, measured in the circulation by radioimmunoassay, has emerged as a useful tool in the evaluation of exocytotic sympathoadrenal activity in man, as well as the diagnosis of the presence and extent of neuroendocrine neoplasia. Here we present current thoughts on the structure and function of chromogranin A, and describe known parameters affecting its plasma concentration.