Predictive Model for Preeclampsia Combining sFlt-1, PlGF, NT-proBNP, and Uric Acid as Biomarkers.

N-terminal pro-brain natriuretic peptide (NT-proBNP) and uric acid are elevated in pregnancies with preeclampsia (PE). Short-term prediction of PE using angiogenic factors has many false-positive results. Our objective was to validate a machine-learning model (MLM) to predict PE in patients with clinical suspicion, and evaluate if the model performed better than the sFlt-1/PlGF ratio alone. A multicentric cohort study of pregnancies with suspected PE between 24+0 and 36+6 weeks was used. The MLM included six predictors: gestational age, chronic hypertension, sFlt-1, PlGF, NT-proBNP, and uric acid. A total of 936 serum samples from 597 women were included. The PPV of the MLM for PE following 6 weeks was 83.1% (95% CI 78.5−88.2) compared to 72.8% (95% CI 67.4−78.4) for the sFlt-1/PlGF ratio. The specificity of the model was better; 94.9% vs. 91%, respectively. The AUC was significantly improved compared to the ratio alone [0.941 (95% CI 0.926−0.956) vs. 0.901 (95% CI 0.880−0.921), p < 0.05]. For prediction of preterm PE within 1 week, the AUC of the MLM was 0.954 (95% CI 0.937−0.968); significantly greater than the ratio alone [0.914 (95% CI 0.890−0.934), p < 0.01]. To conclude, an MLM combining the sFlt-1/PlGF ratio, NT-proBNP, and uric acid performs better to predict preterm PE compared to the sFlt-1/PlGF ratio alone, potentially increasing clinical precision.

NT-proBNP levels in preeclampsia, intrauterine growth restriction as well as in the prediction on an imminent delivery.

OBJECTIVES: Studies of cardiovascular function in pregnancy have shown inconsistent and, in some cases, contradictory results, particularly regarding cardiac output. While some studies report preeclampsia associated with high cardiac output, other studies suggest that preeclampsia should be further subdivided into women with high or low cardiac output. This study was conducted to examine the NT-proBNP levels in preeclampsia, intrauterine growth restriction, and hypertensive pregnancies without preeclampsia. We also examined N-terminal pro-B natriuretic peptide (NT-proBNP) levels three to four months after delivery, in preeclamptic women as well as the prediction of delivery within 10 days. In a reduced number of preeclamptic women and controls we performed echocardiograms to study their diastolic function. METHODS: We investigated the NT-proBNP levels in 213 subjects with preeclampsia only, 73 with intrauterine growth restriction, 44 with preeclampsia and intrauterine growth restriction, 211 who were hypertensive and 662 unaffected pregnancies (controls). We also performed echocardiograms on 36 preeclampsia and 19 controls before delivery and three to five months after delivery. RESULTS: NT-proBNP levels are higher in early onset preeclampsia than in late onset preeclampsia. Intrauterine growth restriction pregnancies showed a NT-proBNP levels similar to hypertensive and unaffected pregnancies. Compared with healthy pregnancies, women with preterm preeclampsia (<37 gestational weeks) had altered left atrial segments. CONCLUSIONS: We observed that NT-proBNP levels are higher in early onset preeclampsia than in late onset. Moreover, diastolic dysfunction is higher in early onset than in late-onset term preeclampsia. An NT-proBNP value >136 pg/mL has a high positive predictive value for an imminent delivery within 10 days.

A more accurate prediction to rule in and rule out pre-eclampsia using the sFlt-1/PlGF ratio and NT-proBNP as biomarkers.

Background The management of potential pre-eclamptic patients using the soluble FMS-like tyrosine kinase 1 (sFlt-1)/ placental growth factor (PlGF) ratio is characterised by frequent false-positive results. Methods A retrospective cohort study was conducted to identify and validate cut-off values, obtained using a machine learning model, for the sFlt-1/PlGF ratio and NT-proBNP that would be predictive of the absence or presence of early-onset pre-eclampsia (PE) in singleton pregnancies presenting at 24 to 33 + 6 weeks of gestation. Results For the development cohort, we defined two sFlt-1/PlGF ratio cut-off values of 23 and 45 to rule out and rule in early-onset PE at any time between 24 and 33 + 6 weeks of gestation. Using an sFlt-1/PlGF ratio cut-off value of 23, the negative predictive value (NPV) for the development of early-onset PE was 100% (95% confidence interval [CI]: 99.5-100). The positive predictive value (PPV) of an sFlt-1/PlGF ratio >45 for a diagnosis of early-onset PE was 49.5% (95% CI: 45.8-55.6). When an NT-proBNP value >174 was combined with an sFlt-1/PlGF ratio >45, the PPV was 86% (95% CI: 79.2-92.6). In the validation cohort, the negative and positive values were very similar to those found for the development cohort. Conclusions An sFlt-1/PlGF ratio <23 rules out early-onset PE between 24 and 33 + 6 weeks of gestation at any time, with an NPV of 100%. An sFlt-1/PlGF ratio >45 with an NT-proBNP value >174 significantly enhances the probability of developing early-onset PE.

Increased serum strontium levels and altered oxidative stress status in early-onset preeclampsia.

BACKGROUND: Correctly distinguishing preeclampsia (PE), gestational hypertension (GH), and intrauterine growth retardation (IUGR) is a challenge for clinicians due to existing similarities. In our previous study, we showed that serum strontium (Sr) levels were elevated in preeclamptic women compared to healthy and GH pregnant women at the end of pregnancy. The main aim of this study was to evaluate Sr and oxidative stress in PE at the time of symptoms onset and before and compare it with IUGR/GH. METHODS: Samples collected at symptoms onset included 77 preeclamptic women and 72 women diagnosed with IUGR/GH divided into two groups according to the gestational extraction week (<34 and ≥ 34). Fifteen patients were also serialized until delivery. Samples collected before symptoms onset included 140 women who developed early-onset PE (E-PE, n = 9), late-onset PE (L-PE, n = 13), IUGR (n = 9), GH (n = 32) and no pathologies (n = 77). Strontium, placental growth factor (PlGF), soluble fms-like tyrosine kinase 1 (sFlt-1), uric acid (UA), creatinine, lipid peroxidation, and total antioxidant activity (TAA) were measured. RESULTS: Mean Sr, sFlt-1/PIGF ratio, UA, and lipid peroxidation/TAA ratio levels were significantly higher (p = 0.002, <0.0001, <0.0001 and = 0.03, respectively) and estimated glomerular filtration rate (eGFR) and TAA significantly lower (p = 0.0008 and < 0.0001, respectively) in E-PE vs other pathologies when gestational extraction week was <34. There was a significant correlation between Sr and eGFR (r = 0.43, p = 0.02), sFlt-1/PIGF ratio (r = 0.56, p = 0.002), TAA and gestational week of sampling (r = -0.45, p = 0.02) and UA (r = -0.82, p < 0.0001) in the E-PE serial samples. No differences were found in Sr levels before symptoms onset. CONCLUSION: Serum Sr concentration and oxidative status are increased in E-PE when compared to other pathologies at the time of symptoms onset. More studies are needed to elucidate the causes of Sr levels elevation and its role in the pathophysiology of PE.

Phenotyping and relative quantification of vitamin D binding protein in a paediatric population by using liquid chromatography-tandem mass spectrometry.

BACKGROUND: Adequate concentrations of vitamin D are required to ensure bone health and minimize the incidence of multiple extraskeletal diseases. Although total 25-hydroxyvitamin D (25OHD) remains the recommended biomarker for assessing vitamin D status, it has been speculated that free 25OHD correlates better with clinical outcomes. The calculation of free 25OHD depends on the concentrations of vitamin D binding protein (DBP), the determination of which involves different immunoassays and has led to varying results and conclusions. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous identification and relative quantification of DBP isoforms. METHODS: We used serum samples from healthy children ( n = 79), mainly Caucasian (88%). Proteins were denatured, reduced, alkylated and digested with trypsin. Purified peptides were analysed by LC-MS/MS. The DBP phenotype was established by using the combinations of tryptic peptides associated with each of the three isoforms and one peptide common to all of them to perform relative quantification. The genotyping of volunteers ( n = 7) facilitated verification of the ability of our method to correctly identify the DBP phenotype. RESULTS: The DBP phenotype was correctly established in all samples from volunteers, based on the 100% correlation observed with the genotype. The most common DBP phenotype in Caucasian children was 2/1S (34%) and the rarest 1F/1F (2%). The relative quantification of DBP concentrations did not show statistically significant differences between phenotypes ( P = 0.11). CONCLUSIONS: LC-MS/MS enabled simultaneous phenotyping and relative quantification of DBP, while avoiding the analytical limitations of immunoassays and confirming similar concentrations of DBP in all phenotypes.

Performance of plasma free metanephrines in diagnosis of pheochromocytomas and paragangliomas in the population of Asturias. / Rendimiento de las metanefrinas libres plasmáticas en el diagnóstico de los feocromocitomas y paragangliomas en la población asturiana.

INTRODUCTION: Pheochromocytoma and paraganglioma are uncommon tumors whose best known symptoms include high blood pressure, palpitations, headache, and sweating. Clinical identification is not easy, however, and requires biochemical tests that allow for early diagnosis, including measurement of metanephrines levels. The aim of this study was to assess the diagnostic performance of plasma free metanephrines (PMETs) and to verify the transferability of the reference values used. METHODS: PMETs levels were measured by liquid chromatography coupled to tandem mass spectrometry. Other biochemical tests evaluated (plasma catecholamine, urine metanephrine, catecholamine and vanilmandelic acid levels) were performed by liquid chromatography with electrochemical detection. Requests of these tests from 01/09/2015 to 31/10/2017 were reviewed, and both the reference values (document EP28-A3c) and the parameters of biological variation (Fraser method) for PMETs were estimated. RESULTS: The study sample consisted of 1,279 patients (61.3% females) aged 0-90 years, including 19 with pheochromocytoma/paraganglioma. Tests requested included: PMETs (n=662), catecholamines (n=589), metanephrines (n=586), and vanilmandelic acid (n=513) in urine, and plasma catecholamines (n=228). Tests with higher sensitivity were urinary fractionated metanephrines (91.7%) and PMETs (82.4%). When performance was compared in patients with both tests (n=243), they detected the same number of tumors (90.9%), but PMETs showed greater specificity (93.5% vs 88.8%). Plasma normetanephrine levels showed a significant association with age (rho=0.19, P<.0001). CONCLUSION: PMETs and urinary fractionated metanephrines are the biochemical tests with better performance in diagnosis of pheochromocytomas/paragangliomas.

Use of the sFlt-1/PlGF ratio to rule out preeclampsia requiring delivery in women with suspected disease. Is the evidence reproducible?

BACKGROUND: Soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) ratio has been proven to predict preeclampsia occurrence. METHODS: Blood samples from 195 pregnant women with suspected preeclampsia were obtained at obstetric triage admission or from the high-risk pregnancy outpatient office. Serum PlGF and sFlt-1 were measured by an electrochemiluminescence immunoassay (ECLIA) on the immunoanalyser Cobas e601 (Roche Diagnostics) and the corresponding ratio was calculated. Final outcomes were reviewed by an independent obstetrician. Only the first determination was considered. RESULTS: A sFlt-1/PlGF ratio of 38 or lower ruled out the need for pregnancy termination due to preeclampsia in the subsequent week with a negative predictive value (NPV) of 99.1% (sensitivity 97.1% and specificity 67.5%). None of the 76 pregnancies with first determination of an sFlt-1/PlGF ratio of 38 or lower between 24 and 34 weeks of gestation delivered due to early-onset preeclampsia. Positive likelihood ratio (PLR) of an sFlt-1/PlGF ratio above 38 for prediction of pregnancy termination due to preeclampsia within 4 weeks is analogous to published evidence. CONCLUSIONS: Between 24 and 34 weeks of gestation, no subsequent determination was needed to completely rule out early-onset preeclampsia when the first sFlt-1/PlGF ratio determination was 38 or lower in singleton pregnancies with signs or symptoms of this syndrome. These findings, if confirmed, will reduce costs and facilitate the implementation of the sFlt-1/PlGF ratio in women with clinical suspicion of preeclampsia in the third trimester.

N-terminal pro B-type natriuretic peptide and angiogenic biomarkers in the prognosis of adverse outcomes in women with suspected preeclampsia.

BACKGROUND: This study compares the performance of the soluble fms-like tyrosine kinase 1 to placental growth factor (sFlt-1/PlGF) ratio and the cardiac biomarker N-terminal pro-B type natriuretic peptide (NT-proBNP) in the prediction of adverse outcomes in women with suspicion of PE. METHODS: A retrospective cohort study was conducted on women admitted at triage with signs and/or symptoms of PE (n=340). Serum levels of sFlt-1, PlGF and NT-proBNP were determined by an electrochemiluminescence immunoassay (Roche Diagnostics). The main outcomes were early- or late-onset PE and development of adverse outcome, defined as delivery within the first week since clinical presentation or fetal/early neonatal death. RESULTS: NT-proBNP concentrations (ng/L) were significantly increased in PE versus non-PE women, both at <34 (169 versus 34) and ≥34weeks of gestation (101 versus 49) (p<0.001). A cut-point of 70 showed sensitivities/specificities of 78/74% for early-, and 70/62% for late-onset PE; slightly lower than those offered by the sFlt-1/PlGF ratio or uric acid. The respective cut-points of 178 and 219 for sFlt-1/PlGF ratio and NT-proBNP, demonstrated similar performance in the prediction of adverse outcome, with sensitivity/specificity of 95/84% and 94/76%, respectively. CONCLUSION: NT-proBNP and sFlt-1/PlGF ratio can be used to predict the development of an adverse outcome.

Interleukin-6 in cerebrospinal fluid as a biomarker of acute meningitis.

BACKGROUND: Microbiological culture of cerebrospinal fluid is the gold standard to differentiate between aseptic and bacterial meningitis, but this method has low sensitivity. A fast and reliable new marker would be of interest in clinical practice. OBJECTIVE: Interleukin-6, secreted by T cells in response to meningeal pathogens and quickly delivered into cerebrospinal fluid, was evaluated as a marker of acute meningitis. DESIGN AND METHODS: A total of 150 cerebrospinal fluid samples were analysed by an electrochemiluminescence method, selected according to patient diagnosis: (a) bacterial meningitis confirmed by positive culture (n = 26); (b) bacterial meningitis with negative culture or not performed (n = 15); (c) viral meningitis confirmed by polymerase chain reaction or immunoglobulin G determination (n = 23); (d) viral meningitis with polymerase chain reaction negative or not performed (n = 42); and (e) controls (n = 44). RESULTS: Cerebrospinal fluid interleukin-6 concentration showed significant differences between all pathologic groups and the control group (P < 0.001). As a diagnostic tool for bacterial meningitis, interleukin-6 showed an area under the curve of 0.937 (95% confidence intervals: 0.895-0.978), significantly higher than those of classical biomarkers. An interleukin-6 cutoff of 1418 pg/mL showed 95.5% sensitivity and 77.5% specificity, whereas a value of 15,060 pg/mL showed 63.6% sensitivity and 96.7% specificity, for diagnosis of bacterial meningitis. CONCLUSION: Interleukin-6 measured by electrochemiluminescence method is a promising marker for early differentiation between aseptic and bacterial meningitis. More studies are needed to validate clinical implications for future practice in an emergency laboratory.

Role of vitamin D and sFlt-1/PlGF ratio in the development of early- and late-onset preeclampsia.

BACKGROUND: The imbalanced production of placental biomarkers and vitamin D deficiency have been proposed as risk factors for the development of preeclampsia (PE). However, little is known about the relationship between them and their role in early- versus late-onset PE. The objectives were to assess the role of 25-hydroxyvitamin D [25(OH)D] concentrations and the soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) ratio in the development of early- and late-onset PE; and to evaluate the relationship between 25(OH)D and the biomarkers. METHODS: A retrospective, full-blinded cohort study was conducted at the Obstetric Emergency Service of a tertiary care hospital. Pregnant women (n=257) attending obstetric triage with suspicion of PE were included. sFlt-1, PlGF and 25(OH)D concentrations were measured by electrochemoluminescence (ECLIA) immunoassay and pregnancy outcome (development of PE) was registered from patients records. RESULTS: PE women showed lower 25(OH)D concentrations at clinical presentation than non-PE women (median: 35.0 nmol/L and 39.6 nmol/L, respectively; p=0.027). Women with 25(OH)D levels <50 nmol/L experienced an increased risk of developing late-onset PE [odds ratio (OR) 4.6, 95% confidence interval (CI) 1.4-15], but no association was found for early-onset PE. However, a sFlt-1/PlGF ratio above the corresponding cutpoints increased the risk of developing both early- and late-onset PE [ORs 58 (95% CI 11-312) and 12 (95% CI 5.0-27), respectively]. No association was found between 25(OH)D levels and sFlt-1/PlGF ratio. CONCLUSIONS: Low vitamin D status in women with suspected late-onset PE increases the risk of imminent development of the disease.

Development of an isotope dilution GC-MS procedure for the routine determination of creatinine in complex serum samples.

The accurate determination of creatinine in serum is essential for the diagnosis and treatment of kidney diseases. The determination of serum creatinine in clinical laboratories is routinely carried out by the Jaffe method or by enzymatic methods that may suffer from interferences. So, the development of reliable, fast and interference-free routine methods for complex serum samples is required. A fast method using isotope dilution mass spectrometry (IDMS) and gas chromatography mass spectrometry (GC-MS) was developed using minimally (13)C labeled creatinine analogs, multiple linear regression and rapid derivatization of creatinine with acetylacetone in 2 min by using focused microwave technology. The proposed method was validated with the analyses of two Certified Reference Materials (ERM-DA252a and ERM-DA253a) and compared with the Jaffe and enzymatic methods when analyzing real serum samples containing variable levels of bilirubin The proposed method is capable of providing accurate serum creatinine concentrations in less than 45 min from sample arrival to full data treatment and can be an alternative routine procedure for creatinine determinations in complex serum samples.

New biomarkers in diagnosis of early onset preeclampsia and imminent delivery prognosis.

BACKGROUND: Several studies have revealed a high soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) ratio in preeclamptic women. However, its role in patients with suspected preeclampsia (PE) at triage in the emergency department remains an issue and a controversial unique cutpoint of 85 has been proposed regardless of gestational age. A new cutpoint for sFlt-1/PlGF ratio was investigated to rule out PE at obstetric triage, and to assess its prognostic value for risk of imminent delivery. METHODS: Blood samples from 257 pregnant women with suspected PE were obtained at obstetric triage admission. Serum PlGF and sFlt-1 were measured by an electrochemoluminiscence immunoassay (ECLIA) on the immunoanalyzer Cobas e601 (Roche Diagnostics) and the corresponding ratio was calculated. Final outcomes (mainly development of PE) were reviewed and time between clinical presentation and delivery was calculated. RESULTS: The best ratio cutpoint to diagnose PE changed according to gestational age: 23 (92.0% sensitivity, 81.1% specificity) and 45 (83.7% sensitivity, 72.6% specificity) for women <34 and ≥ 34 weeks' gestation, respectively. Furthermore, sFlt-1/PlGF ratio inversely correlated with time elapsed between clinical presentation and delivery, and a cutpoint of 178 could predict complications such as imminent delivery or fetal/neonatal death with a sensitivity of 70.6% and a specificity of 97.8%. CONCLUSIONS: The new cut-off values for the sFlt-1/PlGF ratio adjusted by the gestational age at clinical presentation can be used to rule out PE at obstetric triage and to predict imminent delivery with better accuracy than the cutpoint currently accepted.

Biological variation and prognosis usefulness of new biomarkers in liver transplantation.

BACKGROUND: An observational retrospective study has been conducted, including 52 patients (37 male and 15 female), ranging from 22 to 65 years old, who underwent an orthotopic liver transplantation (OLT) at the Hospital Universitario Central de Asturias (HUCA) between 2007 and 2010. METHODS: The main objective was to evaluate the post-OLT critical complication prognosis usefulness of the precursors of three new biomarkers: mid-regional proadrenomedullin (MR-proADM), carboxy-terminal-proendothelin-1 (CT-ProET-1) and mid-regional proatrial natriuretic peptide (MR-ProANP). As all of them are blood pressure mediators, stress-associated physiological phenomena are expected to affect their expression and secretion, mainly those related to blood circulation. Therefore, as a second goal, the biological variability of the biomarkers has been studied in a set of OLT patients without complications during the first postoperative week. The knowledge of the reference change value of the new biomarkers will be interesting for their correct interpretation in future investigations. The prognostic value of the new biomarkers was also compared to that of procalcitonin (PCT). RESULTS: It has been shown that the basal concentration of the biomarkers is higher in patients that undergo OLT than in the normal population, correlating with the severity of the pathology. The intra-individual biological variation of these biomarkers is similar to other biochemical parameters, the reference change value for OLT patients being 90% for CT-proET-1, 112% for MR-proADM and 127% for MR-proANP. CONCLUSIONS: Multivariate analysis showed that MR-proADM was the best biomarker for the prognosis of severe complications.