Utility of icteric index in clinical laboratories: more than a preanalytical indicator.

INTRODUCTION: Total bilirubin tests are highly demanded in clinical laboratories. Since icteric index (I-index) has zero cost, we aimed to evaluate its clinical utility and cost-effectiveness to determine if total bilirubin is necessary to be tested. We took into account if haemolysis could interfere to icteric index determination. MATERIAL AND METHODS: Retrospectively we reviewed I-index results in two cohorts (43,372 and 8507 non-haemolysed and haemolysed samples, respectively). All determinations were done using Alinity c chemistry analysers (Abbott Diagnostics). Receiver operating characteristic (ROC) curve was used to determine the optimal index cut-off to discriminate between normal and abnormal bilirubin concentration (20.5 µmol/L). RESULTS: The ROC curve analysis suggested 21.4 µmol/L as the optimal I-index cut-off but differences in sensitivity and specificity were detected between patient derivation. For rejecting purpose, 15.4 µmol/L and 17.1 µmol/L I-index thresholds were selected based on patient derivation (inpatients and emergency room; and primary care and outpatients, respectively) with 97% sensitivity and 0.25% false negative results. Sensitivity was much lower in haemolysed samples. We selected 34.2 µmol/L I-index as threshold to detect hyperbilirubinemia with 99.7% specificity and 0.26% false positive results, independent of haemolysis. With the icteric index cut-offs proposed, we would save 66% of total bilirubin requested and analyse total bilirubin in around 2% of samples without total bilirubin requested. CONCLUSIONS: This study supports the use of I-index to avoid bilirubin determination and to identify patients with hyperbilirubinemia. This work considers that the economic and test savings could help to increase the efficiency in clinical laboratories.

Neuroapoptosis in newborns with respiratory acidosis at birth.

BACKGROUND: S100B protein is one of the most accurate biomarkers for diagnosis of neuroapoptosis and brain damage. The aim was to evaluate the lactate concentration and acid-base balance (pH, pCO2, pO2, HCO3c and BEb) in umbilical cord blood to predict high risk of neuroapoptosis and analyze the relationship between the levels of these biomarkers and umbilical cord blood S100B protein concentration at birth. METHODS: Apparently healthy newborns were included. S100B protein and blood gas test (lactate and acid-base balance) were determined in umbilical cord blood at birth. Newborns were classified into two groups: with and without high risk of neuroapoptosis. Newborns with high umbilical cord blood S100B protein concentration were considered newborns at high risk of neuroapoptosis. RESULTS: Sixty-one newborns were included, 12 had high risk of neuroapoptosis and 49 did not. S100B protein concentration correlate directly with pCO2 levels (Rho: 0.286, p = .0321) and lactate concentration (Rho: 0.278, p = .0315); and indirectly with pH (Rho: -0.332, p = .01). The analysis of the ROC curves yielded significant curves for pH and pCO2 to predict high risk of neuroapoptosis, pH optimal cutoff value was 7.19 (sensitivity: 50%, specificity: 83.7%, AUC: 0.708); and pCO2 optimal cutoff value was 60 mmHg (sensitivity: 30%, specificity: 85.4%, AUC: 0.705). CONCLUSIONS: Respiratory acidosis is associated to high concentrations of S100B protein in umbilical cord blood at birth. Umbilical cord blood pH and pCO2 may be useful in differentiating newborns at high risk of neuroapoptosis. Umbilical cord blood gas test may be valuable as risk indicator for neuroapoptosis at birth.

Daño cerebral postanestesia general / Brain damage after general anesthesia

Fundamento y objetivo: La proteína S100B es un marcador sérico de daño cerebral. El objetivo fue evaluar el daño cerebral producido por la anestesia general mediante la determinación de la concentración de proteína S100B sérica antes y después de la anestesia general. Pacientes y método: Se incluyeron pacientes con intervención quirúrgica programada de amigdalectomía por hipertrofia amigdalar. En la consulta de preanestesia se extrajo una muestra de sangre venosa (muestra basal). Los pacientes fueron sometidos a anestesia general utilizando los siguientes fármacos anestésicos intravenosos: midazolam, fentanilo y propofol; y sevoflurano inhalado. Al finalizar la intervención quirúrgica y con el paciente aún en quirófano, se extrajo una segunda muestra de sangre venosa (muestra postexposición). Se determinó en suero la concentración de la proteína S100B en la muestra basal (S100Bb) y en la muestra postexposición (S100Bp), mediante inmunoanálisis de electroquimioluminiscencia en el MODULAR E-170 (Roche Diagnostics). Resultados: Se incluyeron 76 pacientes, 46 varones y 30 hembras, con edades entre 3 y 14 años (mediana 5 años). En todos los pacientes, los niveles de proteína S100B sérica aumentaron tras la anestesia general. Los valores obtenidos de S100Bp (mediana 164,0 ng/l) fueron significativamente mayores que los obtenidos de S100Bb (mediana 94,5 ng/l). La mediana de la diferencia entre S100Bp y S100Bb fue de 58,0 ng/l. Mediante el test de Wilcoxon se encontraron diferencias estadísticamente significativas entre S100Bb y S100Bp (p < 0,0001). Conclusiones: La concentración de proteína S100B sérica aumentó significativamente tras la anestesia general. Esto indica que la anestesia general puede producir daño cerebral (AU)

Background and objective: S100B protein is a serum marker of cerebral damage. The objective was to evaluate the brain damage caused by general anaesthesia, by determining the concentration of serum S100B protein before and after of general anaesthesia. Patients and method: Patients with chronic adenotonsillar hypertrophy and indications for tonsillectomy were included. A venous blood sample was taken from the patients before general anaesthesia (basal sample). The patients were anaesthetised using the following intravenous anaesthetic drugs: midazolam, fentanyl and propofol; and inhaled sevoflurane. A second venous blood sample (postoperative sample) was taken from patients after the surgery, in the operating room. The concentration of serum S100B protein was determined in the basal sample (S100Bb) and postoperative sample (S100Bp) by immunoassay electro-chemiluminescence in MODULAR E-170 (Roche Diagnostics). Results: Seventy-six patients were included, 46 males and 30 females, aged between 3 to 14 (median 5 years). In all the patients, serum S100B protein levels increased after general anaesthesia. The values of S100Bp (median 164.0 ng/L) were significantly higher than the values of S100Bb (median 94.5 ng/L). The median of the difference between S100Bp and S100Bb was 58.0 ng/L. There were statistically significant differences between S100Bb and S100Bp using the Wilcoxon test (P < .0001). Conclusions: The concentration of serum S100B protein increased significantly after general anaesthesia. This indicates that general anaesthesia may cause brain damage (AU)

[Brain damage after general anesthesia]. / Daño cerebral postanestesia general.

BACKGROUND AND OBJECTIVE: S100B protein is a serum marker of cerebral damage. The objective was to evaluate the brain damage caused by general anaesthesia, by determining the concentration of serum S100B protein before and after of general anaesthesia. PATIENTS AND METHOD: Patients with chronic adenotonsillar hypertrophy and indications for tonsillectomy were included. A venous blood sample was taken from the patients before general anaesthesia (basal sample). The patients were anaesthetised using the following intravenous anaesthetic drugs: midazolam, fentanyl and propofol; and inhaled sevoflurane. A second venous blood sample (postoperative sample) was taken from patients after the surgery, in the operating room. The concentration of serum S100B protein was determined in the basal sample (S100Bb) and postoperative sample (S100Bp) by immunoassay electro-chemiluminescence in MODULAR E-170 (Roche Diagnostics). RESULTS: Seventy-six patients were included, 46 males and 30 females, aged between 3 to 14 (median 5 years). In all the patients, serum S100B protein levels increased after general anaesthesia. The values of S100Bp (median 164.0 ng/L) were significantly higher than the values of S100Bb (median 94.5 ng/L). The median of the difference between S100Bp and S100Bb was 58.0 ng/L. There were statistically significant differences between S100Bb and S100Bp using the Wilcoxon test (P<.0001). CONCLUSIONS: The concentration of serum S100B protein increased significantly after general anaesthesia. This indicates that general anaesthesia may cause brain damage.

Evaluation of Pleural Fluid Lactate for Diagnosis and Management of Parapneumonic Pleural Effusion.

BACKGROUND: The aim was to measure the accuracy of pleural fluid lactate concentration for diagnosis of parapneumonic pleural effusion (PPE) and to discriminate between uncomplicated (UPPE) and complicated PPE (CPPE). METHODS: Pleural fluid lactate was measured in patients with pleural effusion. Patients were classified into two groups according to the etiology of pleural effusion: PPE and NOT PPE. RESULTS: We studied 173 patients. Thirty patients were PPE (10 UPPE and 20 CPPE) and 143 were NOT PPE. The AUC value was 0.831 (p < 0.0001) and the optimal cutoff value was 5.6 mmol/L exhibiting 70% sensitivity and 90.9% specificity for diagnosis of PPE. Also, pleural fluid lactate could be used to discriminate between UPPE and CPPE, the AUC value was 0.740 (p = 0.0089) and the optimal cutoff value was 10.2 mmol/L, exhibiting 45% sensitivity and 90% specificity. CONCLUSIONS: Pleural fluid lactate has a high accuracy for diagnosis and management of PPE.

Homocysteine: new tumor marker in pleural fluid.

There are no published studies examining the utility of total homocysteine (HCY) in pleural fluid. The aim was to measure the accuracy of pleural fluid HCY concentration for diagnosis of malignant pleural effusion (MPE). We studied pleural fluids obtained by thoracocentesis in patients with pleural effusion. Pleural fluid HCY concentration was measured by immunonephelometry using N Latex HCY reagent with monoclonal antibody in automated analyzers BNII (Siemens Diagnostics®). Patients were classified into two groups according to the etiology of pleural effusion: benign pleural effusions (BPE) and MPE. Pleural effusion was categorized as MPE if malignant cells were demonstrated in pleural fluid or pleural biopsy. The accuracy of pleural fluid HCY concentration for diagnosis of MPE was determined using receiver operating characteristic (ROC) techniques by analyzing the area under the ROC curve (AUC). We studied 89 patients with ages between 1 and 96 years old (median = 66). Forty-eight patients were BPE and 41 were MPE. Pleural fluid HCY concentration was significantly higher in patients with MPE (median = 13.70 µmol/L) than in those with BPE (median = 8.05 µmol/L). The AUC value was 0.833 (95 % confidence interval (CI) 0.739-0.903). The optimal cutoff value was 13.1 µmol/L exhibiting 56.1 % (95 % CI 39.8-71.5) sensitivity and 85.4 % (95 % CI 72.2-93.9) specificity. Pleural fluid HCY concentration showed high diagnostic accuracy to predict whether a pleural effusion is benign or malignant. Pleural fluid HCY concentration may be measured easily and quickly in automated analyzers and could be a tumor marker commonly used for diagnosis of MPE.

Serum lactate dehydrogenase in combination with free-to-total serum prostate specific antigen ratio for diagnosis of prostate cancer.

BACKGROUND: Evaluate the utility of serum lactate dehydrogenase (LDH) in combination with free-to-total serum prostate specific antigen ratio (%fPSA), for diagnosis of prostate cancer (PC) with serum total prostate specific antigen (PSA) levels in the intermediate range of 4 to 10 ng/mL. METHODS: The following variables were analysed: PSA, %fPSA, and LDH. Two categories of patients were included in the analysis: NOT PC and PC. RESULTS: We studied 134 patients, 112 had NOT PC and 22 had PC. We defined the following multivariable score (S): S = A + B, where A and B are coefficients of LDH and %fPSA, respectively. AUC values were 0.719 (p = 0.0036), 0.749 (p = 0.0082), and 0.816 (p = 0.0001) for %fPSA, LDH, and S, respectively. Using the proposed S increases by 18% specificity compared to only using the %fPSA parameter. CONCLUSIONS: LDH in combination with %fPSA improves diagnostic performance for detection of PC compared to using only %fPSA.