Analytical Evaluation of Lumipulse Anti-Mullerian Hormone Assay.

BACKGROUND: The measurement of serum Anti-Mullerian hormone (AMH) is used in daily practice to estimate the ovarian reserve in women. METHODS: The aim of this study was to evaluate the new Lumipulse AMH® immunoassay (Fujirebio) with regard to the reliability with two preexisting assays: Elecsys AMH Plus® (cobas®, Roche) and Vidas AMH® (bioMérieux). Precision of Lumipulse AMH was evaluated on the Lumipulse G600 II using the manufacturer's quality controls. Thirty-three samples were used for method comparison. RESULTS: Lumipulse AMH repeatability and intermediate precision did not exceed 4.1 %. There was a proportional bias between Lumipulse and Cobas method and between Lumipulse and Vidas whereas a good agreement was found between Cobas and Vidas. CONCLUSIONS: Lumipulse AMH assay demonstrated good precision and good agreement with the two other methods up to 6 ng/mL. Nevertheless, this study shows the need to standardize AMH assays to improve the comparability of the methods.

Preliminary evaluation of the diagnostic performance of Roche Elecsys® active vitamin B12 versus total vitamin B12 for vitamin B12 deficiency screening.

INTRODUCTION: The prevalence of vitamin B12 deficiency is high in at-risk populations with sometimes irreversible consequences. Beside total B12 (TVB12), active B12 (AVB12) is a promising first-line marker. Only Abbott AVB12 assays were largely evaluated and generally demonstrated benefit in clinical practice. More recently developed Roche AVB12 still requires some investigations. OBJECTIVES: Our study aimed to evaluate the Roche Elecsys® AVB12 immunoassay performance versus Roche Elecsys® TVB12 competition assay. DESIGN: and Methods: We included 175 patients at Rouen University Hospital who had a TVB12 value <300 pmol/L. We evaluated performance of AVB12 by comparing the results with TVB12 and MMA values in case of disagreement. RESULTS: Positive correlation was found between the AVB12 and TVB12. We found a disagreement between TVB12 and AVB12 in 18.8% of cases. Among 33 cases of disagreement, 76% had normal AVB12 but low TVB12, whereas 24% had low AVB12 and normal TVB12. Thirty-one MMA determinations were performed: 71% showed agreement between MMA and AVB12, versus 29% between MMA and TVB12. TVB12 reported a sensitivity (Se) at 66.7%, specificity (Sp) at 20%, positive predictive value (PPV) at 16.7% and negative predictive value (NPV) at 71.4% for the prediction of MMA elevation. We determined an optimized cut-off value of 45.5 pmol/L for AVB12, which reported a Se 66.7%, Sp 60%, PPV 30.7%, and NPV 88.9%. CONCLUSIONS: Our results provide preliminary evidence that Roche AVB12 may offer better discrimination than Roche TVB12 in the diagnosis of vitamin B12 deficiency. Further more detailed evaluation is warranted.

Huge discrepancy between serum immunoglobulin concentration and proteinemia due to heavy chain disease.

Immunoassays are widely used in clinical laboratories because of their ease of use and low cost. These tests are based on antigen-antibody binding. However, clinicians and laboratory personnel may be confronted with immunoassay interference leading to difficulties in medical care. Here, we report a huge analytical discrepancy with IgG concentration higher than proteinemia in a 75-year-old man. Serum electrophoresis and immunofixation diagnosed γ-heavy chain disease. After investigation by different methods, the assay discrepancy was still present. We hypothesize that the interference is related to the truncated immunoglobulin secreted by the lymphoproliferative disorder.

[Acute hemolysis crisis revealed a Wilson disease]. / Diagnostic d'une maladie de Wilson devant une anémie hémolytique.

Wilson disease is a rare inherited disorder of copper metabolism that affects liver and brain due to copper tissue accumulation. The mechanism involved is based on mutations of the ATP7B gene. Children have predominant hepatic manifestations while adult are more often diagnosed by neurological and psychiatric symptoms. However, others features are tubulopathy, articular disorders and hemolytic anemia. We report the diagnostic of Wilson disease in a 14 years old girl and her sibling after investigation of hemolytic anemia, hepatic insufficiency, and hypophosphatemia.

Interest of adjusting urine cannabinoids to creatinine level to monitor cannabis cessation therapy in heavy smokers with psychiatric disorders.

Up to 25% of hospitalized patients in a psychiatric department exhibit troubles linked to cannabis use. Weaning patients with psychiatric disorders off drugs of abuse requires specific care to improve their clinical outcome. The present study aims to develop a predictive model of urinary excretion of creatinine-normalized cannabinoids (UCNC ) and to determine UCNC thresholds corresponding to the widely used cut-offs of 20 ng/mL and 50 ng/mL for cannabinoids. One hundred thirty-two patients with 452 urine samples were included between 2013 and 2017. Urinary cannabinoids and UCNC elimination curves were computed for each patient. Using a mono-exponential mixed effect model with 88 samples from 26 subjects exhibiting at least 3 decreasing UCNC in a row, the average calculated elimination rate constant was 0.0108 ± 0.0026 h-1 , corresponding to a mean elimination half-life of 64 ± 12 hours. The use of UCNC is of particular interest because of a high inter- and intra-individual variability of urinary creatinine concentration (from 0.06 to 3.81 mg/mL). Moreover, UCNC allows for the detection of diluted or concentrated urine specimens that may lead to false positive (FP) or false negative (FN) results. Receiver operator characteristic (ROC) curves were used to assess UCNC thresholds of 32.4 and 124.7 ng/mg that provide a strong discrimination between positive and negative samples for cannabinoids cut-offs of 20 and 50 ng/mL respectively. The developed model and the defined UCNC thresholds allowed for the accurate prediction of the time needed to reach a negative UCNC result that could be used by clinicians to optimize clinical care.