Abstract
This work discusses the clinical performance of chromogranin A (CGA), a commonly measured marker in neuroendocrine neoplasms, for the diagnosis of pheochromocytoma/paraganglioma (PPGL). Plasma CGA (cut-off value 150 µg/L) was determined by an immunoradiometric assay. Free metanephrine (cut-off value 100 ng/L) and normetanephrine (cut-off value 170 ng/L) were determined by radioimmunoassay. Blood samples were collected from PPGL patients preoperatively, one week, six months, one year and two years after adrenal gland surgery. The control patients not diagnosed with PPGL suffered from adrenal problems or from MEN2 and thyroid carcinoma. The clinical sensitivity in the PPGL group of patients (n = 71) based on CGA is 90% and is below the clinical sensitivity determined by metanephrines (97%). The clinical specificity based on all plasma CGA values after surgery (n = 98) is 99% and is the same for metanephrines assays. The clinical specificity of CGA in the control group (n = 85) was 92% or 99% using metanephrines tests. We can conclude that plasma CGA can serve as an appropriate complement to metanephrines assays in laboratory diagnosis of PPGL patients. CGA is elevated in PPGLs, as well as in other neuroendocrine or non-neuroendocrine neoplasia and under clinical conditions increasing adrenergic activity.
Highlights
In this work we present our experiences with radioimmunoassay of plasma chromogranin A (CGA) in the laboratory diagnosis of neuroendocrine tumors classified as pheochromocytoma (PCC)and paraganglioma (PGL)
recurrence of the disease (REC) were not included in the clinical specificity and sensitivity calculations listed in Tables 1 and 2 since such increased values can be normalized by not administering pump inhibitors (PPIs) to patients, or long-term kidney failure or the recurrence of pheochromocytoma/ paraganglioma (PPGL) must be taken into consideration when interpreting the results as the case may be
Figure together with medullary thyroid carcinoma (MTC), follicular thyroid carcinoma (FTC) or papillary was not included in the control group because he suffered from chronic renal insufficiency
Summary
In this work we present our experiences with radioimmunoassay of plasma chromogranin A (CGA) in the laboratory diagnosis of neuroendocrine tumors classified as pheochromocytoma (PCC)and paraganglioma (PGL). In this work we present our experiences with radioimmunoassay of plasma chromogranin A (CGA) in the laboratory diagnosis of neuroendocrine tumors classified as pheochromocytoma (PCC). Neuroendocrine cells are widely dispersed cells with dense core granules similar to those dense core granules present in serotonergic neurons (neuro properties), which store bioactive amines and peptide hormones (endocrine properties) [1,2]. These cells do not contain synapses [1,3]. Neuroendocrine neoplasms can be divided into functional and non-functional tumors; the former ones are usually diagnosed at an earlier stage due to endocrine symptoms related to hormonal production, whereas the non-functional tumors remain silent and are frequently diagnosed when metastasis has already occurred [2,5]
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