Rhona M. Jack

Improving the Value of Costly Genetic Reference Laboratory Testing With Active Utilization Management

CONTEXT Tests that are performed outside of the ordering institution, send-out tests, represent an area of risk to patients because of complexity associated with sending tests out. Risks related to send-out tests include increased number of handoffs, ordering the wrong or unnecessary test, specimen delays, data entry errors, preventable delays in reporting and acknowledging results, and excess financial liability. Many of the most expensive and most misunderstood tests are send-out genetic tests. OBJECTIVE To design and develop an active utilization management program to reduce the risk to patients and improve value of genetic send-out tests. DESIGN Send-out test requests that met defined criteria were reviewed by a rotating team of doctoral-level consultants and a genetic counselor in a pediatric tertiary care center. RESULTS Two hundred fifty-one cases were reviewed during an 8-month period. After review, nearly one-quarter of genetic test requests were modified in the downward direction, saving a total of 2% of the entire send-out bill and 19% of the test requests under management. Ultimately, these savings were passed on to patients. CONCLUSIONS Implementing an active utilization strategy for expensive send-out tests can be achieved with minimal technical resources and results in improved value of testing to patients.

Quercetin, an Over-the-Counter Supplement, Causes Neuroblastoma-like Elevation of Plasma Homovanillic Acid

A 22-month-old boy, who regularly consumed the oral dietary supplement, quercetin, was suspected erroneously of having a catecholamine-producing tumor, based on elevated serum and urine levels of the dopamine metabolite, homovanillic acid (HVA). Subsequent studies of healthy adult volunteers showed that significant elevations in plasma HVA are a consequence of quercetin ingestion.

Cimetidine clearance in the obese

Six subjects with normal weight (mean weight = 62 kg) and six obese subjects (mean weight = 140 kg) were given a single intravenous cimetidine infusion of 600 mg over 10 to 15 minutes. Both groups of subjects had normal serum creatinine levels and were matched with respect to age, desirable body weight, height, renal function, and sex. Compared with subjects of normal weight, obese subjects had higher cimetidine systemic (1147 and 637 ml/min) and renal (808 and 318 ml/min) clearances. Volume of distribution at steady state was of the same order for the two groups (82 and 84 L), but the t½ was shorter in the obese group (1.2 and 1.9 hr). Obese subjects had lower cimetidine sulfoxide serum concentrations and greater cimetidine sulfoxide renal clearance (856 and 509 ml/min). Cimetidine systemic clearance and cimetidine sulfoxide renal clearance values were of the same order in the two groups when normalized by the value of weight raised to the 0.76 and 0.5 powers. Under the assumptions of an average weight of 70 kg and that average serum concentrations produced by cimetidine, 300 mg iv every 6 hours, are appropriate, people with normal renal function and body weight usually receive 48 mg/day/weight0.76. This same dosage in obese individuals with normal serum creatinine values should result in the same average steady‐state serum concentrations. In our obese subjects, the mean cimetidine dose would have been approximately 500 mg iv every 6 hours.

Real Time Free Cortisol Quantification Among Critically Ill Children

Objectives: Ascertainment of adrenal function assessing free rather that total cortisol may be beneficial for the diagnosis of critical illness-related cortisol insufficiency. We hypothesized that centrifugal ultrafiltration would provide timely free cortisol data that highly correlated with the gold standard, but logistically cumbersome, equilibrium dialysis technique when the free cortisol fractions were identically quantified by chemiluminescence immunoassay. We also hypothesized that free cortisol would correlate with illness severity in a large cohort of critically ill children. Design: Prospective, multi-institutional, observational cohort investigation. Setting: Seven pediatric intensive care units within the Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network. Patients: One hundred sixty-five critically ill children across the spectrum of illness severity. Interventions: Blood sampling. Measurements and Main Results: Time to derive plasma free cortisol concentrations after centrifugal ultrafiltration or equilibrium dialysis fractionation with chemiluminescence immunoassay was approximately 2 vs. approximately 24 hrs, respectively. Using centrifugal ultrafiltration, mean plasma free cortisol was 4.1 ± 6.7 &mgr;g/dL (median, 1.6 &mgr;g/dL; range, 0.2–43.6 &mgr;g/L), representing an average of 15.2 ± 9.4% of total cortisol. Nearly 60% of subjects exhibited free cortisol <2 and 30% <0.8 &mgr;g/dL, previously suggested threshold concentrations for defining critical illness-related cortisol insufficiency. Plasma-free cortisol concentrations comparing centrifugal ultrafiltration vs. equilibrium dialysis fractionation demonstrated a strong correlation (R2 = 0.97). For free cortisol <2 &mgr;g/dL, Bland-Altman analysis revealed minimal negative bias for the centrifugal ultrafiltration technique. Illness severity assessed by Pediatric Risk of Mortality III correlated moderately with free cortisol and percent total cortisol as free cortisol. Conclusions: Determination of centrifugal ultrafiltration fractionated free cortisol was fast and results correlated highly with equilibrium dialysis fractionated free cortisol. Many children exhibited free cortisol <2 and <0.8 &mgr;g/dL but did not demonstrate clinical evidence of critical illness-related cortisol insufficiency. This study ascertains that real-time free cortisol quantification is feasible to potentially help guide clinical decisionmaking for cortisol replacement therapy in the pediatric intensive care unit.

Exposure to environmental tobacco smoke during pregnancy in rats yields less effect on indices of brain cell number and size than does postnatal exposure.

While there is evidence that human perinatal exposure to environmental tobacco smoke (ETS) can result in an increased risk of respiratory disorders and sudden infant death syndrome, evidence linking ETS exposure to neurodevelopmental handicaps is suggestive but less compelling. We previously noted that postnatal ETS exposure, rather than prenatal exposure, resulted in reduced concentration of hindbrain DNA and increased protein/DNA ratio when rat brain tissue was studied at 9 weeks postnatal age. We have now evaluated the effects of ETS exposure during pregnancy on brain development by assaying brain tissue at term. ETS exposure had no detectable effects on regional brain concentrations of DNA, protein and cholesterol or on protein/DNA and cholesterol/DNA ratios. While ETS exposure during pregnancy also had no detectable effects on the weights of the individual fetuses or on the weights of various organs, certain regions of the fetal skeleton demonstrated accelerated ossification. The findings of this study are contrasted to the developmental effects of both nicotine and ETS in Rhesus macaques. Additional studies designed specifically to assess the risk of prenatal ETS exposure on brain development in non-human primates and other precocial species are warranted.

Tacrolimus and sirolimus in capillary dried blood spots allows for remote monitoring.

Therapeutic drug monitoring of tacrolimus and sirolimus plays a significant role in the clinical follow‐up of transplant patients receiving IMS therapy. Success of transplant and favorable patient outcome relies on maintaining adequate therapeutic drug levels. The purpose of this research is to assess the clinical utility of remote collection of DBS for immunosuppressant monitoring and compare the IMS level in paired collections of venous whole blood and DBS. Sirolimus and tacrolimus levels were clinically correlated in capillary blood collected from a finger poke with venous whole blood from pediatric, post‐transplant patients. The participants took the dried blood spot card home with them with a pre‐addressed, postage‐paid envelope and mailed it back to the laboratory. Overall, a small but statistically significant negative bias was observed (−0.6 ng/mL, p = 0.0011). A chart review was performed to assess whether clinical management would have changed, and none of the cases revealed a clinically significant change. Sirolimus in DBS also correlated with venous levels. Overall, a small but statistically negative bias was observed (−0.8 ng/mL, p = 0.029). In summary, analysis of IMS levels in DBS is possible, and the difference noted between capillary and venous blood is within the clinically acceptable limits.

Under-filled blood collection tubes containing K2EDTA as anticoagulant are acceptable for automated complete blood counts, white blood cell differential, and reticulocyte count.

Current laboratory standards from Clinical Laboratory Standards Institute (CLSI) and manufacturer’s (Becton Dickinson) data indicate that under‐filling K2EDTA blood collection tubes can result in erroneous hematology values. To accommodate under‐filled tubes and reduce collection volumes while optimizing our automation, we explored the acceptable limit of under‐filled tubes for hematology values. We collected 8.0 ml of blood from 30 normal adult volunteers. Each donation was aliquoted in the following volumes: 4.0, 2.0, 1.0, 0.5 ml × 2. These samples were analyzed within 1 h of blood collection on Sysmex XE‐2100 (Sysmex America Inc., Mundelein, IL, USA) for complete blood count, reticulocyte, and white blood cell differentials. Results of the under‐filled tubes were compared to those of the standard volume. The Deming regression analysis show excellent correlation for all parameters between each under‐filled blood collection volume compared to a standard 4 ml volume. The Bland and Altman analysis shows good agreement between both 1.0 and 2.0 ml compared to a 4.0 ml volume. The 0.5 ml compared to a 4.0 ml volume, however, shows increased variation on many parameters. In addition all three collection volumes show negative bias compared to the standard volume for platelet count, but the difference is considered insignificant with a percent difference of 5.5%, 3.2%, and 1.5% for 0.5, 1.0, and 2.0 ml collection volume respectively. Finally for 0.5 ml collection volume we noticed a low level of false positive flagging rate for white blood cell. Acceptable complete blood count values of under‐filled powdered K2EDTA tubes can be obtained with as little as 1.0 ml of blood.

Lethal neonatal case and review of primary short-chain enoyl-CoA hydratase (SCEH) deficiency associated with secondary lymphocyte pyruvate dehydrogenase complex (PDC) deficiency

Mutations in ECHS1 result in short-chain enoyl-CoA hydratase (SCEH) deficiency which mainly affects the catabolism of various amino acids, particularly valine. We describe a case compound heterozygous for ECHS1 mutations c.836T>C (novel) and c.8C>A identified by whole exome sequencing of proband and parents. SCEH deficiency was confirmed with very low SCEH activity in fibroblasts and nearly absent immunoreactivity of SCEH. The patient had a severe neonatal course with elevated blood and cerebrospinal fluid lactate and pyruvate concentrations, high plasma alanine and slightly low plasma cystine. 2-Methyl-2,3-dihydroxybutyric acid was markedly elevated as were metabolites of the three branched-chain α-ketoacids on urine organic acids analysis. These urine metabolites notably decreased when lactic acidosis decreased in blood. Lymphocyte pyruvate dehydrogenase complex (PDC) activity was deficient, but PDC and α-ketoglutarate dehydrogenase complex activities in cultured fibroblasts were normal. Oxidative phosphorylation analysis on intact digitonin-permeabilized fibroblasts was suggestive of slightly reduced PDC activity relative to control range in mitochondria. We reviewed 16 other cases with mutations in ECHS1 where PDC activity was also assayed in order to determine how common and generalized secondary PDC deficiency is associated with primary SCEH deficiency. For reasons that remain unexplained, we find that about half of cases with primary SCEH deficiency also exhibit secondary PDC deficiency. The patient died on day-of-life 39, prior to establishing his diagnosis, highlighting the importance of early and rapid neonatal diagnosis because of possible adverse effects of certain therapeutic interventions, such as administration of ketogenic diet, in this disorder. There is a need for better understanding of the pathogenic mechanisms and phenotypic variability in this relatively recently discovered disorder.

Evaluation of Multiplex Antinuclear Antibody Assay in Pediatric Patients

Objective: To determine whether multiplex antinuclear assay (ANA) can replace immunofluorescence assay (IFA) in pediatric patients. Methods: Archived frozen serum samples from patients with suspected autoimmune diseases were selected based on the availability of leftover serum samples with corresponding results. These samples had been previously tested for ANA using IFA methodology (101 samples), dsDNA (93 samples), and ENA (27 samples) by ELISA methods. Antinuclear assay screen was performed on these samples using the AtheNA Multi-Lyte ANA Test System. Results: There was a high level of discordance (45.5% concordance) between multiplex ANA screen and IFA method but strong correlation between multiplex ANA and specific autoantibody assays (89% to 96% concordance). All patients with positive ANA by IFA method, who were either diagnostic or suspicious for juvenile idiopathic arthritis (JIA), were negative by multiplex ANA assay. Conclusion: Multiplex ANA testing is an efficient and reliable method for detecting specific antinuclear antibodies; however, it cannot replace IFA as an ANA screening method in the pediatric population, especially for children with JIA.

Another laboratory test utilization program: our approach to reducing unnecessary 1,25-dihydroxyvitamin D orders with a simple intervention.

To the Editor We were very interested in the report by Jeffrey Warren1 outlining a comprehensive laboratory test utilization program in a large academic medical center. The report highlighted the implementation of an interdisciplinary committee to review utilization patterns, appropriateness, and new test requests in combination with significant information technology (IT) resources dedicated to computerized provider order entry decision tools. Over 5 years, they decreased send-out testing expenses normalized to clinical laboratory expenses. We implemented a similar laboratory test utilization program in a 250-bed pediatric hospital that processes approximately 1,000 requisitions daily. Send-out expenses are a proportionally large burden on clinical laboratory and hospital budgets.2 We developed a strategy to manage “flagged” test requests with minimal IT resources. Our utilization committee operates similarly to the committee …