A correction formula for neuron‑specific enolase measurement in hemolyzed neonatal serum samples

Abstract

Abstract. As a specific biomarker in neonatal hypoxic-ischemic encephalopathy (HIE), the measurement of neuron-specific enolase (NSE) has been advocated as a predictor of outcome in neurological injury. However, the measured levels of NSE may be influenced by hemolysis. In the current study, the change in the concentration of NSE in serum was measured by chemiluminescence prior to and following the addition of individual frozen and thawed red blood cells from 86 neonates that were collected within 24 h of birth. The changes in the concentration of NSE were compared with the changes in the concentration of hemoglobin (Hb), measured by the hemoglobin cyanide (HiCN) method, to establish a correction formula. The performance of the correction formula was evaluated by comparing the corrected concentration of NSE using the individual constants and the correction formula. The average individual constant of NSE from the 86 hemolyzed neonatal serum samples was 25.15±3.94 mg/g Hb. The concentration variation between NSE and Hb in neonatal sera could be described by the equation ΔNSE serum =1.8594+24.0670 xΔHb HiCN (r²= 0.8045, P<0.001). There was no statistically significant difference in the NSE corrected results between the individual constant group and the correction formula group (Z=-1.645, P=0.100). The linear regression formula of Hb measured with the instrumental method compared with the HiCN method was Hb instr = 0.9816xHb HiCN +0.5596 (r²= 0.9924, P<0.001). Based on these regression analyses, the correction formula for NSE in hemolyzed neonatal serum was determined as NSE corr =NSE meas -24.0670xHb HiCN -1.8594 or NSE corr = NSE meas -24.5181xHb instr +11.8609. In conclusion, hemolysis has a substantial influence on the accurate measurement of NSE in neonatal serum samples. For hemolyzed neonatal serum samples, correcting the NSE results using a correction formula is essential to evaluate the severity of neonatal hypoxic ischemic encephalopathy. IntroductionHypoxic-ischemic encephalopathy (HIE) secondary to perinatal asphyxia remains a major cause of neonatal mortality and morbidity worldwide (1,2). The incidence of HIE ranges from 1 to 3 per 1,000 full-term infants and is present in almost 60% of premature newborns (3-5). Approximately 15-20% of affected newborns succumb within the postnatal period, and an additional 25% develop severe and permanent neuropsychological handicaps, including cerebral palsy, seizures, visual impairment, mental retardation, learning disabilities and epilepsy (5).Neuron-specific enolase (NSE) belongs to the family of enolase enzymes present in all tissues and organisms capable of glycolysis (6). Enolases consist of three subunits (α, β, and γ) encoded by separate genes. These subunits may combine to form five different isoenzymes: αα, αβ, αγ, ββ and γγ (6). NSE, comprised of γγ homodimers and αγ heterodimers, is widely distributed in central nervous system neurons and amine precursor uptake and decarboxylation cells (7). As a marker of neuronal cell death, the serum concentration of N...

Correction of the NSE concentration in hemolyzed serum samples improves its diagnostic accuracy in small-cell lung cancer

“…As previously mentioned, very divers hemolysis correction equations are described in current literature and the equation developed in this study is again different [2,3,11]. This can be explained by multiple factors, such as the difference in hemolysis interference between newborns and adults or the variability between measurement systems used to detect hemolysis and serum NSE.…”

“…Neuron-specific enolase (NSE) is a dimeric metalloenzyme which functions as a cell specific isoenzyme of the glycolytic enzyme enolase [ 1 ]. It is comprised of γγ homodimers and αγ heterodimers that are predominantly expressed in mature neurons and cells of neuronal origin, although the αγ heterodimer can also be found in erythrocytes and platelets and released upon hemolysis [ 2 , 3 ]. Previously, the NSE concentration in serum was shown to correlate with tumor burden, metastasis and treatment response in tumors of neuroendocrine origin such as small-cell lung cancer (SCLC) [ 1 , 4 , 5 ].…”

“…Previously, various correction equations for NSE detection in neonatal serum samples suffering from brain injuries were established [ 3 , 11 ]. However, since the NSE concentration in erythrocytes of newborns substantially differs from that of adults (± 25 μg NSE/mg hemoglobin (Hb) and ± 25 ng NSE/mg Hb respectively), these equations cannot be used in lung cancer diagnostics [ 2 , 3 ]. Other earlier developed correction equations for NSE quantification in adults were based on detection methods prone to assay interference [ 2 ].…”

An Update on Postoperative Cognitive Dysfunction Following Cardiac Surgery

“…On the contrary, there was an elevation in Neuron-Specific enolase in 49% of patients following surgery, but there was no association with POCD. As neuron-specific enolase is also found in erythrocytes and platelets, this elevation may be attributed to haemolysis as a result of blood surface interactions during on-pump cardiac surgery [106,107]. Similarly, in a secondary analysis of 148 patients, Holmgaard et al 2019 did not detect an association between the duration or extent of rSO2 desaturations >10% compared to baseline with the incidence of POCD at discharge, or 3 months post-operatively.…”

An Update on Postoperative Cognitive Dysfunction Following Cardiac Surgery

“…On the contrary, there was an elevation in Neuron-Specific enolase in 49% of patients following surgery, but there was no association with POCD. As neuron-specific enolase is also found in erythrocytes and platelets, this elevation may be attributed to haemolysis as a result of blood surface interactions during on-pump cardiac surgery ( 109 , 110 ). Similarly, in a secondary analysis of 148 patients, Holmgaard et al ( 111 ) did not detect an association between the duration or extent of rSO2 desaturations >10% compared to baseline with the incidence of POCD at discharge, or 3 months post-operatively.…”