Rose T. Daher

25-Hydroxyvitamin D Assay Variations and Impact on Clinical Decision Making

CONTEXT Laboratories are increasingly shifting to new automated 25-hydroxyvitamin D (25-OHD) assays, with subsequent variability in results. OBJECTIVE/SETTING We describe the experience at our center with such a shift and illustrate its clinical implications. METHODS 25-OHD levels were measured in 494 patients using Immunodiagnostic Systems RIA (IDS-RIA) and DiaSorin Liaison assays. Sources of variability between the assays were investigated in a subset of 83 samples, retested in the reference laboratory in the United States, and by reviewing the performance reports issued by the International Vitamin D External Quality Assessment Scheme, DEQAS. 25-OHD cut-points for target levels were used to compare the two assays. RESULTS 25-OHD concentrations were significantly lower when measured with Liaison as compared to IDS-RIA: mean bias was -5 ng/ml, range was -38.1 to 18.7 ng/ml, P<0.001; the absolute bias was independent of 25-OHD value. Interassay variability was also detected in values obtained in the reference laboratory and in DEQAS reports. Using 20 ng/ml as the target 25-OHD level, 52% of patients required treatment when tested by Liaison, as opposed to 36% by IDS-RIA (P<0.001). Using 30 ng/ml as the desirable level, the proportions were 79 and 64%, respectively (P<0.001). The two assays agreed in only 41-68% of subjects, proportions that depended on criteria used to define agreement. CONCLUSION A change in 25-OHD assays has a significant impact on results, patient classification, and treatment recommendations. Such variability cannot be ignored when deriving and applying vitamin D guidelines. It also renders universal assay standardization a pressing call.

Relation Between Iron-Overload Indices, Cardiac Echo-Doppler, and Biochemical Markers in Thalassemia Intermedia

Cardiovascular impairment is a major cause of morbidity and mortality in patients with thalassemia intermedia. In this study, echocardiographic assessment of left heart condition was performed in patients with thalassemia intermedia, and its relation to hematologic variables--amino terminal pro-brain natriuretic peptide (NT-proBNP), ferritin, hemoglobin--and liver iron concentration (LIC) was investigated. Echocardiographic assessment was performed using pulse-wave Doppler and tissue Doppler imaging. Data from 74 patients with thalassemia intermedia--35 men, 39 women, mean age 26.5 years (8 to 63)--were randomly selected and evaluated. Blood samples were collected for NT-proBNP levels in a random subgroup of 19 patients. Mean baseline values were hemoglobin 8.4 g/dl (4.9 to 13.1), serum ferritin 902.6 ng/ml (15 to 4,140), LIC 9.0 mg Fe/g (0.5 to 32.1), and NT-proBNP 113.5 pg/ml (16.4 to 371). Correlation between LIC and pulmonary artery systolic pressure was significant, suggesting that iron loading in the liver is indicative of cardiovascular sequelae. NT-proBNP was significantly correlated with the ratio of the left ventricular early rapid filling wave to early diastolic velocity at the mitral annulus (r = 0.50, p = 0.04) and hemoglobin (r = -0.49, p = 0.03), but not with other characteristics assessed. In conclusion, this study has highlighted the importance of using tissue Doppler imaging rather than pulse-wave Doppler to characterize left ventricular diastolic dysfunction in patients with thalassemia intermedia. Demonstration of the correlation of LIC and pulmonary artery systolic pressure independent of left ventricular filling pressures supports our hypothesis that left ventricular diastolic dysfunction does not contribute to the increased pulmonary artery systolic pressure in patients with thalassemia intermedia.

High Prevalence of MTHFR Gene A1298C Polymorphism in Lebanon

BACKGROUND Mutations in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene could reduce the enzyme activity and lead to hyperhomocysteinemia, a condition that has been associated with several vascular conditions, in particular, coronary artery disease and deep vein thrombosis. AIM The aim of this study was to assess the prevalence of the two most common polymorphisms, C677T and A1298C, which have not been well studied in the Lebanese population. METHODS We randomly selected 205 healthy individuals originating from different Lebanese provinces and religious communities. The CVD StripAssay was used to test for MTHFR gene polymorphisms. RESULTS We found that for C677T, the prevalence of C/C, C/T, and T/T genotypes was 65.3%, 30.8%, and 3.9%, respectively, with an overall carrier rate of 34.6% and allelic frequency of 0.19. However, the A1298C genotypic prevalence of A/C, A/A, and C/C was 50.2%, 25.9%, and 23.9%, respectively, with an overall carrier rate of 74.14% and an allelic frequency of 0.49. CONCLUSIONS Compared to all other populations reported so far, the Lebanese population harbors the highest prevalence of the MTHFR A1298C polymorphism. This is an important finding to be followed in terms of clinical significance and sheds light on an additional unique genetic feature in this community.

Comparison of neutrophil volume distribution width to C-reactive protein and procalcitonin as a proposed new marker of acute infection

Abstract Background: The aim of this study was to assess the use of neutrophil distribution width (NDW) and to compare it to C-reactive protein (CRP) and procalcitonin (PCT), in the detection of early sepsis in the intensive care unit. Methods: Subjects (N = 166) were divided into 4 groups: healthy, acute inflammatory non-infectious (AINI), localized infection, and systemic infection, according to clinical history and cultures. NDW, CRP, and PCT were compared among the different groups using multivariate analysis of variance (MANOVA). Diagnostic efficacy was assessed using receiver operating characteristic curves and areas under the curves (AUC). Results: The lowest meanNDW was found in the healthy group (n = 41), followed by the AINI (n = 20), localized infection (n = 55), and systemic infection (n = 50) groups. AUCNDW was 0.877 for infected (localized + systemic) vs non-infected (healthy + AINI) groups, and 0.965 for systemic infection vs non-infected groups. A cut-off of 21.9 resulted in 90% sensitivity, 92% specificity, 90% positive predictive value, and 92% negative predictive value (AUCNDW = 0.965, 95% confidence interval 0.935–0.995). According to MANOVA, only NDW was able to differentiate an acute inflammatory process from early infection in postoperative patients, but not healthy from AINI subjects. Conclusions: NDW had the highest diagnostic accuracy and is available with the complete blood count with differential (CBC). It may be a promising parameter to aid in the diagnosis of acute infection in adults, provided the possibility of haematological disorders is first ruled out.

Extended use of serum free light chain as a biomarker in lymphoproliferative disorders: a comprehensive review.

Serum free light chain (sFLC) assays were shown to improve detection, management, and prognostication in plasma cell disorders. Recently, sFLC assays improved detection of M proteins when combined with standard methods of protein electrophoresis/immunofixation in patients with non-Hodgkin lymphoma/chronic lymphocytic leukemia (NHL/CLL). Incidence of abnormal sFLC ratio (sFLCr) varied from 0% to 36% and 29.7% to 59% in NHL and CLL, respectively. Increased sFLC levels or abnormal sFLCr predict shorter overall survival in early-stage CLL. Furthermore, abnormal sFLCr correlated with advanced disease stage and poorer outcome. In diffuse large B-cell lymphomas, increased sFLC was demonstrated as an independent, adverse prognostic factor for overall/event-free survival. Moreover, abnormal sFLCr can be a diagnostic tool in central nervous system lymphomas. Finally, the quantitative FLC assay has the potential to become a new, easily measured biomarker for predicting prognosis and enhanced detection in NHL/CLL. It may be used serially at follow-up evaluations to provide clues to relapse.

A NEONATAL SCREENING IN LEBANON: RESULTS OF FIVE YEARS EXPERIENCE

BACKGROUND Neonatal screening programs for common disorders like phenylketonuria, congenital hypothyroidism, and glucose-6-phosphate dehydrogenase (G6PD) deficiency are not fully established at the national level in Lebanon. Screening for the above disorders was carried out for newborns delivered at the American University of Beirut Medical Center over a period of five years. SUBJECTS AND METHODS Blood specimens collected 2-3 days after birth were applied to neonatal screening blood collection cards. A total of 9117 newborns were screened using phenylalanine, thyroid-stimulating hormone, and G6PD activity measurements on blood spots. RESULTS One case of phenylketonuria and another of hyperphenylalaninemia were detected. We also detected 5 cases of permanent type of congenital hypothyroidism, giving an incidence of 5:9117 (1:1823). The age range at initiation of hormonal replacement therapy was 9-46 days. The overall incidence of G6PD was 106:9117 (1:86 or 1.16%), of which 84 had complete deficiency (1:109 or 0.92%), and 22 with intermediate activity. CONCLUSION The incidence of these disorders found in this Lebanese sub-population warrants consideration of a comprehensive nationwide neonatal screening program.

Diagnostic challenges of aminoacidopathies and organic acidemias in a developing country: A twelve-year experience

BACKGROUND Diagnosis of aminoacidopathies and organic acidemias constitutes a real challenge in a developing country with high consanguinity rate and no systematic newborn screening. We report a twelve-year experience with the identification of these disorders in Lebanon, based on their clinical and biochemical profiles. METHODS In this retrospective study, we reviewed clinical presentation and biochemical investigations of 294 patients. Traditional chromatographic methods were used for analyses. Findings were linked to the identified disorders. RESULTS Out of 2921 patients, presenting to our metabolic program with neurological, digestive, family history and/or other symptoms suggestive of aminoacidopathy or organic acidemia, 294 patients were included with confirmed amino or organic acid disorder. The overall analytical yield was 10%. Aminoacidopathies were three-fold higher than organic acidemias. Phenylketonuria and methylmalonic acidemia were the most frequent. The majority of patients (79%) were symptomatic (median age: 14months, range: 1day-44years), mainly with neurological manifestations (87%). Intellectual disability was mostly due to phenylketonuria (73%). Chronic liver failure was frequent in maple syrup urine disease (53%). Plasma amino and urine organic acid chromatography were diagnostic in 8.8% and 3.9% of analyzed cases, respectively. Change in chromatographic technique from reversed-phase to ion-exchange enhanced the detection of many aminoacidopathies. CONCLUSIONS In the absence of newborn screening, the majority of aminoacidopathy and organic acidemia cases are still diagnosed clinically. This study emphasizes the importance of clinical awareness and accurate biochemical analyses as key tools for diagnosis in countries like ours, and the necessity for a comprehensive national newborn screening program.

ApoB-100 R3500Q mutation in the Lebanese population: Prevalence and historical review of the literature

An interesting mutation affecting the Apo-B gene, R3500Q, is known to display variable geographical distribution in the world and is mostly implicated in the pathogenesis of Familial Hypercholesterolemia (FH). The aim of this study is to determine the prevalence of this mutation in the Lebanese population and compare it to the available international literature. DNA from 160 unrelated healthy donors from our HLA-bank was used and the ApoB genotype was determined using the CardioVascular Disease (CVD) StripAssay (this assay is based on a Polymerase Chain Reaction-Reverse Hybridization technique). The R3500Q mutation was not observed in the general Lebanese population. Since the mutation frequency is elevated in Central Europe and tends to decrease as one moves east and south, it disappears completely in the Mediterranean regions such as Spain, Turkey and Israel; therefore, it is rather expected to be absent in Lebanon as well. Our report adds a valuable piece of information regarding this mutation in an Arab country and paves the way for future research involving patients diagnosed with FH in order to assess the role of the R3500Q mutation in the development of this clinical entity.

Serum Flt3 Ligand Variation as a Predictive Indicator of Hematopoietic Stem Cell Mobilization

Flt3 ligand (FL) is a good indicator of bone marrow (BM) cellularity, having a reciprocal relationship with white blood cell (WBC) count in aplastic anemia and chemotherapy-induced neutropenia. In this report, serum FL level was measured by enzyme-linked immunosorbent assay (ELISA), in 16 consecutive patients undergoing autologous peripheral stem cell transplantation, with an average of 12 selected levels for each patient based on major changes of WBC counts at different procedure stations. We found a significant increase of serum FL level at the WBC nadir after mobilization chemotherapy and a more dramatic increase at the WBC nadir post transplantation, consistent with a more profound BM aplasia after myeloablative chemotherapy as compared to high-dose cyclophosphamide used for mobilization. Hence, we reproduced the reciprocal relationship between serum FL and BM cellularity. A direct correlation between the increase of FL level after mobilization chemotherapy and the length of mobilization was also established, which may help physicians, at the individual patient level, to predict the time of stem cell collection. Finally, we showed a direct correlation between the peripheral CD34+ count at the time of stem cell collection and the peak FL level after transplantation, which can reflect BM stromal cell function. Our results suggest that variation of serum FL level may be used as predictive indicator of hematopoietic stem cell (HSC) mobilization.

Experience with hyperphenylalaninemia in a developing country: unusual clinical manifestations and a novel gene mutation.

We report our experience in a cohort of patients with hyperphenylalaninemia in a tertiary care referral center in Lebanon. Forty-one sequential patients were studied: 34 classical phenylketonuria (PKU), 3 hyperphenylalaninemia (non-PKU), and 4 biopterin metabolism defects. The majority of cases were clinically diagnosed at variable ages with variable neurological outcomes. Only 29.3% were detected by neonatal screening. Two unusual cases were observed in the context of inadequate treatment in 1 and delayed therapy in the other: a newborn with PKU developed severe keratomalacia; and a 5-year-old girl with dihydropteridine reductase deficiency due to a novel mutation identified in the quinoid dihydropteridine reductase gene developed Lennox-Gastaut syndrome and white matter changes with periventricular cysts. Part of our experience parallels that in the West. However, the clinical manifestations observed in our patients emphasize the importance of a national newborn screening program with efficient management of diagnosed cases.