Biological variation of plasma chromogranin A

Chromogranin A plasma levels predict mortality in COVID-19

Background

Chromogranin A (CgA) and its fragment vasostatin I (VS-I) are secreted in the blood by endocrine/neuroendocrine cells and regulate stress responses. Their involvement in Coronavirus 2019 disease (COVID-19) has not been investigated.

Methods

CgA and VS-I plasma concentrations were measured at hospital admission from March to May 2020 in 190 patients. 40 age- and sex-matched healthy volunteers served as controls. CgA and VS-I levels relationship with demographics, comorbidities and disease severity was assessed through Mann Whitney U test or Spearman correlation test. Cox regression analysis and Kaplan Meier survival curves were performed to investigate the impact of the CgA and VS-I levels on in-hospital mortality.

Results

Median CgA and VS-I levels were higher in patients than in healthy controls (CgA: 0.558 nM [interquartile range, IQR 0.358–1.046] vs 0.368 nM [IQR 0.288–0.490] respectively, p = 0.0017; VS-I: 0.357 nM [IQR 0.196–0.465] vs 0.144 nM [0.144–0.156] respectively, p<0.0001). Concentration of CgA, but not of VS-I, significantly increased in patients who died (n = 47) than in survivors (n = 143) (median 0.948 nM [IQR 0.514–1.754] vs 0.507 nM [IQR 0.343–0.785], p = 0.00026). Levels of CgA were independent predictors of in-hospital mortality (hazard ratio 1.28 [95% confidence interval 1.077–1.522], p = 0.005) when adjusted for age, number of comorbidities, respiratory insufficiency degree, C-reactive protein levels and time from symptom onset to sampling. Kaplan Meier curves revealed a significantly increased mortality rate in patients with CgA levels above 0.558 nM (median value, log rank test, p = 0.001).

Conclusion

Plasma CgA levels increase in COVID-19 patients and represent an early independent predictor of mortality.

Limited Diagnostic Utility of Chromogranin A Measurements in Workup of Neuroendocrine Tumors

BACKGROUND

Plasma chromogranin A (CgA) is related to tumor burden and recommended in the follow-up of patients diagnosed with neuroendocrine tumors (NETs). The use of CgA in the workup of a suspected NET is more questionable.

OBJECTIVE

To assess the positive predictive value (PPV) of CgA plasma concentrations above the upper reference limit (URL) in patients with suspected NET.

METHOD

Patients referred to the NET Centre, Rigshospitalet, Copenhagen from 2015 to 2019 with clinically suspected NET were included if a CgA measurement was performed prior to referral. The utility of CgA was assessed by comparing pre-referral CgA concentrations to the outcome of a thorough workup. In 47 selected cases with continuously unexplained elevated CgA concentrations, a processing-independent analysis (PIA) for CgA was performed.

RESULTS

A total of 197 patients were included. NET was ultimately diagnosed in 25 patients. CgA plasma concentrations were above the URL (elevated) in 19/25 patients diagnosed with NET. In total, 167/197 had elevated CgA concentrations at referral. The positive predictive value (PPV) of elevated CgA concentration was 11% (19/167). Proton pump inhibitor (PPI) treatment was identified as the possible cause of CgA elevation in 55/148 patients with falsely elevated CgA. CgA concentration was normal in 28/47 patients when using PIA.

CONCLUSION

Our data do not support using measurement of CgA for screening when NET is suspected since the PPV was rather low. PPI treatment is a common cause of increased CgA concentrations and should always be discontinued before CgA measurement. PIA of CgA could be a way of excluding NET when suspicion is based primarily on elevated CgA.

Chromogranin A as biomarker in diabetes

Chromogranin A (CgA) is an established plasma marker of neuroendocrine tumors and has been suggested to also have a role as biomarker in other diseases. Whether CgA has any role as biomarker in diabetes is, however, unresolved, but its widespread distribution in the secretory granules in endocrine tissues including β cells and α cells in pancreas, and the metabolic effects of its peptide fragments suggest that CgA may play a pathophysiological role in diabetes, and thus also be a potential diabetes biomarker. In this review, we summarize the available information on CgA and some of its functional post-translational cleavage products in diabetes, followed by a discussion of its potential as a plasma marker in diabetes and the methodological concerns involved.

Evaluation of a new immunoassay for chromogranin A measurement on the Kryptor system

Background

Chromogranin A (CgA) is a biomarker for neuroendocrine tumors (NETs). The aims of this study were to evaluate differences in measurement between the ThermoFisher Brahms CgA Kryptor assay and the CisBio assay and to investigate the influence of patient covariates. Temperature stability of CgA using both assays was determined.

Design and Methods

406 patients were analyzed for serum CgA using both assays. We performed a comparison study to determine whether several patient covariates (gender, use of protein pump inhibitors, impaired kidney function, referral department and tumor location) influenced the results. For the stability study, pooled serum samples were aliquoted and stored at different storage temperatures (room temperature, 4 °C and −20 °C) until assayed. In addition, 15 individual samples were evaluated after storage at 4 °C using the Kryptor assay.

Results

Differences in measured concentrations between the assays were statistically significant. Passing & Bablok fit showed ln Y(Kryptor)=1.05 ln X(CisBio) – 0.20 with a bias of 1.0% after logarithmic transformation. Patient covariates were not associated. Patients׳ sera showed variable stability for CgA in the Kryptor assay at room temperature and 4 °C, whereas the recovery in the CisBio assay was stable at both temperatures.

Conclusion

Differences in measured CgA concentration between the assays could not be explained by the investigated patient covariates. Serum should be stored at –20 °C prior to determination using the Kryptor assay.

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A Kryptor assay measured significant higher levels of CgA compared with CisBio.

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Difference between Kryptor and CisBio not explained by patient covariates in this study.

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Storage at room temperature and 4 °C should be avoided when using the Kryptor assay.

The biochemical utility of chromogranin A, chromogranin B and cocaine- and amphetamine-regulated transcript for neuroendocrine neoplasia

Neuroendocrine neoplasia (NEN) is a heterogeneous group of tumours and often represents a therapeutic challenge to clinicians. The peptides chromogranin A (CgA), chromogranin B (CgB) and cocaine- and amphetamine-regulated transcript (CART) are widely distributed throughout the neuroendocrine system. CgA and CgB have been used as general NEN biomarkers for many years, while CART has only recently been identified. Of these biomarkers, CgA is the most commonly used. However, circulating CgA concentrations exhibit considerable intra-individual biological variation, are altered by proton pump inhibitors (PPIs) and somatostatin analogues and are elevated in non-NEN malignancies. Therefore, interpretation of CgA results must be in the context of these confounding factors. The effects of treatment and non-NEN conditions on circulating CgB and CART concentrations are less well understood. CgB is less affected by impaired renal function and PPIs than CgA; while, circulating CART concentrations lack a diurnal variation in humans and are more reliable markers of pancreatic NEN malignancy than CgA. The utility of circulating CgA measurements in NEN prognosis, surveillance and disease recurrence has been widely investigated. However, the utility of CgB and CART in NEN management is yet to be elucidated. Further studies are needed to establish whether CgB and CART are useful alternatives to CgA.

Plasma chromogranin A after severe burn trauma

BACKGROUND

Chromogranin A (CgA) in plasma (P-CgA), a neuroendocrine marker of sympathetic stress, has been shown to predict mortality in medical intensive care. We hypothesized that the magnitude of CgA release would reflect stress load, and thereby injury severity in burn intensive care patients.

METHODS

Fifty-one consecutive patients with a burn area exceeding 10% were included. P-CgA was measured twice daily for seven days after injury. The point value at 24h, the mean and maximum values and the AUC at days 1-7, were tested as possible predictors. Injury severity in the form of organ dysfunction was measured as SOFA score at day 7.

RESULTS

P-CgA could be classified into two types with respect to variability over time. Patients with high variability had more deep injuries and were older than those with low variability. All measures of CgA correlated with SOFA score at day 7, but not with total burn size. Univariate regressions showed that age, burn size and three of four measures of P-CgA predicted organ dysfunction. Multiple regressions showed that age, burn size, and either P-CgA at 24h, the mean value up to day 7, or the maximum value up to day 7, were independent predictors for organ dysfunction. Significant organ dysfunction was best predicted by age, burn area and the CgA point value at 24h with an AUC value of 0.91 in a ROC-analysis.

CONCLUSIONS

The extent of neuroendocrine activation assessed as P-CgA after a major burn injury is independently related to organ dysfunction.

Inside ST-elevation myocardial infarction by monitoring concentrations of cardiovascular risk biomarkers in blood

BACKGROUND

No information is available on the optimal sampling time to catch the highest increase for biomarkers whose elevation after ST-elevation myocardial infarction (STEMI) is prognostic for adverse events. This study aimed to investigate release kinetics and peak times of cardiac troponin I (cTnI), C-reactive protein (CRP), B-type natriuretic peptide (BNP), chromogranin A (CgA) and cystatin C (CyC) in STEMI patients undergoing primary percutaneous coronary intervention (PPCI).

METHODS

Blood concentrations of cTnI, CRP, BNP, CgA and CyC were measured before and 6 h, 24 h, and 48 h after PPCI in 84 STEMI patients. The averaged trajectory of marker kinetics was estimated by multivariable regression models adjusted for patient characteristics and orthogonal polynomials were used to describe related releases.

RESULTS

From the estimated kinetics cTnI peaked at 10 h from symptoms, BNP at 28 h and CRP within 30 h. CyC concentrations did not change, whereas CgA concentrations increased from 6 to 48 h after PPCI. The amount of BNP release was found to be affected by the interaction between gender and age: females<75 years had BNP concentrations fourfold higher than males.

CONCLUSIONS

According to different release kinetics a single blood sampling for measuring all biomarkers is not recommended.

Discontinuation of proton pump inhibitors during assessment of chromogranin A levels in patients with neuroendocrine tumours

Background:

The aim of this prospective study was to examine whether discontinuation of proton pump inhibitors (PPIs) or replacement by H₂-receptor antagonists (H2RA) resulted in a decrease of chromogranin A (CgA) levels in 196 patients with well-differentiated neuroendocrine tumours (NETs).

Methods:

Patients with an unexpectedly high CgA level not connected with NET disease discontinued PPIs, or used H2RA instead; 2 weeks later CgA level was measured again.

Results:

In all, 19 out of 196 (10%) patients showed unexpected elevated CgA levels, they all used PPI. In 11 out of 19 patients with no evidence of the disease, median CgA decreased from 390 μg l⁻¹ during PPI treatment to 56 μg l⁻¹ after discontinuation (P=0.003). In 8 out of 19 patients with stable disease, median CgA decreased from 618 to 318 μg l^–1 (P=0.012). In 12 out of 19 patients who ceased all acid inhibition, CgA levels decreased by 82%, while in the seven patients who replaced PPI by H2RA, CgA decreased by 77% (P=0.967).

Conclusion:

Proton pump inhibitor use causes falsely elevated CgA levels in patients with NET. We recommend to stop, or replace PPI by H2RA, to obtain a reliable CgA value.