Evaluation of thyroid test utilization through analysis of population-level data.

BACKGROUND: Inappropriate laboratory test utilization can result in unnecessary patient testing and increased healthcare costs. While several thyroid function tests are available, thyroid-stimulating hormone (TSH) is recommended as the first-line test for investigating and monitoring thyroid dysfunction. We evaluate thyroid test utilization in Northern Alberta in terms of testing patterns, frequencies, and reflex cutpoints. METHODS: This retrospective study analyzed thyroid test requests from January to December 2014. Each request was designated as appropriate or potentially inappropriate as per clinical practice guidelines and Choosing Wisely recommendations, and the frequencies of each testing pattern were calculated. Sub-analysis was performed to categorize testing patterns based on physician specialty. The number of test requests per patient was determined to assess the appropriateness of testing frequency. Receiver operating characteristic (ROC) curves were generated to define optimal TSH cutpoints for automatic reflex to FT4 testing. RESULTS: Of 752,217 test requests, approximately 10% were potentially inappropriate in terms of testing patterns. Free thyroxine (FT4) and free triiodothyronine (FT3) requested with TSH accounted for 59% of all potentially inappropriate test requests, and 49% of requests from endocrinologists (ENDO) were potentially inappropriate, occurring most frequently among those with less experience. Excessive testing frequencies were observed in 869 patients, accounting for 9382 test requests. Adjustment of our TSH reflex cutpoint would significantly increase specificity for identifying a low FT4 without compromising sensitivity. CONCLUSIONS: This study suggests that questionable testing patterns, excessive testing frequencies, and suboptimal reflexive testing cutpoints contribute to inappropriate thyroid test utilization.

Mitotic regulation of SEPT9 protein by cyclin-dependent kinase 1 (Cdk1) and Pin1 protein is important for the completion of cytokinesis.

Precise cell division is essential for multicellular development, and defects in this process have been linked to cancer. Septins are a family of proteins that are required for mammalian cell division, but their function and mode of regulation during this process are poorly understood. Here, we demonstrate that cyclin-dependent kinase 1 (Cdk1) phosphorylates septin 9 (SEPT9) upon mitotic entry, and this phosphorylation controls association with the proline isomerase, Pin1. Both SEPT9 and Pin1 are critical for mediating the final separation of daughter cells. Expression of mutant SEPT9 that is defective in Pin1 binding was unable to rescue cytokinesis defects caused by SEPT9 depletion but rather induced dominant-negative defects in cytokinesis. However, unlike SEPT9 depletion, Pin1 was not required for the accumulation of the exocyst complex at the midbody. These results suggest that SEPT9 plays multiple roles in abscission, one of which is regulated by the action of Cdk1 and Pin1.

Digesting all the options: laboratory testing for celiac disease.

Celiac disease is a complex immune-mediated disorder that is triggered by ingestion of gluten and related proteins in genetically susceptible individuals. Under conditions of increased intestinal permeability, gluten-derived peptides can travel across the intestinal epithelium and undergo deamidation catalyzed by the tissue transglutaminase (TTG) enzyme. This renders them immunogenic in individuals expressing specific human leukocyte antigen (HLA) DQ heterodimers. The resulting immune response is characterized by the production of antibodies against both deamidated gliadin peptides (DGP) and TTG, generation of pro-inflammatory cytokines and activation of cytotoxic T cells. This response damages the intestinal epithelium resulting in the wide range of gastrointestinal and systemic symptoms observed in those with celiac disease. Celiac disease diagnosis has traditionally been based on biopsy and histological examination of the small intestine. While this approach is still considered the gold standard, it is invasive and susceptible to both false-positive and false-negative results. Several laboratory tests have become available to aid in the diagnosis and monitoring of celiac disease, and are the focus of this review. These include serological tests for celiac disease-specific antibodies such as anti-endomysial antibodies, anti-TTG antibodies and anti-DGP antibodies of both the immunoglobulin A (IgA) and immunoglobulin G (IgG) class, genetic tests to elucidate HLA DQ status and ancillary tests such as total IgA. While some have suggested that laboratory tests may replace intestinal biopsy in specific circumstances, others maintain that this procedure remains a critical component of celiac disease diagnosis. We review the analytical methodology, strengths, weaknesses, diagnostic performance and clinical utility of the various laboratory tests for celiac disease. Potential future markers and tests that are now considered obsolete are also discussed. Current clinical practice guidelines for the diagnosis and management of celiac disease from the European Society for Pediatric Gastroenterology, Hepatology and Nutrition, the American College of Gastroenterology and the World Gastroenterology Organisation are summarized, and important differences between these guidelines are highlighted.

Metal release from hip prostheses: cobalt and chromium toxicity and the role of the clinical laboratory.

Individuals with advanced hip disease suffer from pain, impaired hip function, and decreased quality of life. Roughly one million metal-on-metal (MoM) hip prostheses have been implanted worldwide in order to ameliorate these issues. While most MoM hip replacements are successful, some patients suffer from serious adverse effects secondary to the release of metal debris due to implant wear and corrosion. MoM hip prostheses are comprised predominantly of cobalt and chromium, and the serum concentration of these metal ions has been shown to correlate with both implant wear and the accumulation of metal debris in the periprosthetic tissue. Consequently, measurement of cobalt and chromium concentrations may be useful in the assessment of implant function and the potential for adverse effects in the follow-up of patients with MoM hip prostheses. The purpose of this Mini Review is to describe the adverse biological consequences of metal release from hip prostheses, provide an overview of the clinical utility of cobalt and chromium measurement and the current recommendations for testing, and alert laboratorians and physicians to the many challenges associated with measuring these metal ions.

Characterization of presynaptic septin complexes in mammalian hippocampal neurons.

Septins are GTPases that form heteromeric complexes and are linked to neurological disorders. Although several septin subcomplexes have been reported in various mammalian tissues, the cellular and subcellular distribution of these complexes is largely unexplored. Using antibodies against ten mammalian septins, we show that septins diverge with respect to their tissue distribution implying that septin complexes in various tissues have unique composition. Although all ten septins examined were expressed in brain tissue, we describe septin complex(es) including SEPT3, SEPT5, SEPT6, SEPT7 and SEPT11 that could be functional within the presynapse because, unlike other septins they: (1) showed an increase in expression from embryonic day 15 to post-natal day 70, (2) were abundantly expressed in axons and growth cones of developing hippocampal neurons, (3) were found in presynaptic terminals of mature synapses, (4) were enriched in a preparation of synaptic vesicles and (5) immunoprecipitated together from brain tissue and cultured nerve cells. Knockdown of SEPT5 or SEPT7 in developing hippocampal neurons impaired axon growth. Because septins are functionally linked to the cytoskeleton and vesicle traffic, presynaptic neuronal septin complexes could be important for ensuring proper axon development and neurotransmitter release.

Evaluation of interference from hemoglobin C, D, E and S traits on measurements of hemoglobin A1c by fifteen methods.

BACKGROUND: Hemoglobin C, D Punjab, E or S trait can interfere with hemoglobin A1c (HbA1c) results. We assessed whether they affect results obtained with 15 current assay methods. METHODS: Hemoglobin AA (HbAA), HbAC, HbAD Punjab, HbAE and HbAS samples were analyzed on 2 enzymatic, 4 ion-exchange HPLC and 9 immunoassay methods. Trinity Premier Hb9210 boronate affinity HPLC was the comparative method. An overall test of coincidence of least-squared linear regression lines was performed to determine if HbA1c results were statistically significantly different from those of HbAA samples. Clinically significant interference was defined as >6% difference from HbAA at 6 or 9% HbA1c compared to Premier Hb9210 using Deming regression. RESULTS: All methods showed statistically significant effects for one or more variants. Clinically significant effects were observed for the Tosoh G11 variant mode (HbAD), Roche b 101 (HbAC and HbAE) and Siemens DCA Vantage (HbAE and HbAS). All other methods (Beckman Coulter B93009 and B00389 on DxC700AU, and Unicel DxC, Ortho Clinical Vitros 5.1, Roche cobas c 513, Siemens Dimension RxL and Vista, and Enzymatic on Advia and Atellica, Tosoh G8 5.24 and 5.28, and GX) showed no clinically significant differences. CONCLUSIONS: A few methods showed interference from one or more variants. Laboratories need to be aware of potential HbA1c assay interferences.

Is the diagnostic rate for the common subtypes of A1AT deficiency consistent across two Canadian Provinces?

BACKGROUND: The diagnosis of alpha-1-antitrypsin (A1AT) deficiency has been hindered by obscurity concerning the testing process and treatment implications. In this study, we aimed to identify regional differences in the diagnostic rates for A1AT deficiency in the western Canadian provinces of British Columbia (BC) and Alberta (AB). METHODS: The number of A1AT deficiency variant genotype (ZZ, SZ, MZ, SS, and MS) diagnoses were reviewed for BC and AB. The regional diagnostic rates for A1AT deficiency variants in these two provinces, normalized for the predicted population prevalence of each variant genotype, was defined as the annual provincial diagnostic rate (APDR) for a given variant genotype. Sex specific variations in the mean age at diagnosis for the five variant genotypes were compared both within and between provinces. RESULTS: The SZ and MZ genotype APDRs were significantly increased in the AB population compared to the BC population. The SS and MS APDRs were similar between AB and BC. There was a significantly decreased mean age of diagnosis for AB males, as compared to BC males (for the SZ, MS, and MZ genotypes) and as compared to AB females (for the MS, MZ, and SS genotypes). There were no significant differences in the mean age of diagnosis between the females and males in BC, or between females in AB and BC, for any genotype. CONCLUSION: The notably higher APDR for more severe A1AT deficiency genotypes, and lower mean age of diagnosis for most variant genotypes in AB males, deserves further investigation to determine the explanation(s) for these differences.

NullCanada: A novel α1-antitrypsin allele with in cis variants Glu366Lys and Ile100Asn.

BACKGROUND: α1-Antitrypsin (A1AT) deficiency predisposes patients to pulmonary disease due to inadequate protection against human neutrophil elastase released during inflammatory responses. A1AT deficiency is caused by homozygosity or compound heterozygosity for A1AT variants; individuals with A1AT deficiency most commonly have at least one Z variant allele (c.1096G > A (Glu366Lys)). Null variants that result in complete absence of A1AT in the plasma are much rarer. With one recent exception, all reported A1AT variants are characterized by a single pathogenic variant. CASE: An 8 years old patient from Edmonton, Alberta, Canada, was investigated for A1AT deficiency. His A1AT phenotype was determined to be M (wild type)/Null by isoelectric focusing (IEF) but M/Z by targeted genotyping. Gene sequencing revealed two heterozygous variants: Z and Ile100Asn (c.299 T > A). The Ile100Asn substitution is predicted to disrupt the secondary structure of an α-helix in which it resides and the neighbouring tertiary structure, resulting in intracellular degradation of A1AT prior to hepatocyte secretion. METHODS: Family testing was conducted to verify potential inheritance of an A1AT allele carrying the two mutations in cis, as this arrangement of the mutations would explain "Z" detection by genotyping but not by IEF. Molecular modeling was used to assess the effect of the variants on A1AT structure and stability. DISCUSSION: Carrier status for a novel variant NullCanada with in cis mutations (c.[299 T > A;1096G > A], p.[(Ileu100Asn;Glu366Lys)]) was confirmed. A sibling was identified as having A1AT deficiency on the basis of compound heterozygosity for two alleles: NullCanada and the common Z allele. A separate pedigree from the Maritimes was subsequently recognized as carrying NullCanada. CONCLUSION: In cis mutations such as NullCanada may be more common than previously described due to failure to detect such mutations using historical testing methods. Combined approaches that include gene sequencing and segregation studies allow recognition of rare A1AT variants, including in cis mutations.

Alpha-1-antitrypsin molecular testing in Canada: A seven year, multi-centre comparison.

BACKGROUND: Laboratory confirmation of alpha-1-antitrypsin (A1AT) deficiency may be achieved by multiple methods. Here, we compare the relative comprehensiveness and efficiency of pathogenic variant (PV) detection of four different protocols utilized at different diagnostic centres in Canada. METHODS: Diagnostic results from 2011 to 2018 at clinical laboratories in British Columbia (BC), Alberta (AB), Ontario (ON), and Québec (QC) were reviewed. The four labs utilize the following protocols: BC-CGID (serum A1AT Concentration/Genotyping/Isoelectric focussing (IEF)/SERPINA1 DNA sequencing), AB-CID (serum A1AT Concentration/IEF/DNA sequencing), ON-CD (serum A1AT Concentration/DNA sequencing), and QC-G (Genotyping). As the respective catchment areas varied in size and ethnic composition, the comprehensiveness of PV detection was assessed by comparing the frequency of individual genotypes to the ZZ genotype, which is clearly identified by all protocols. RESULTS: Collectively 5399 index patients were tested identifying 396 ZZ genotypes. Serum A1AT concentration as a determinant of further testing efficiently identified PV. ON-CD had the highest detection rate for PV; genotypes with at least one PV, other than S, Z or F, were identified at 0.67/ZZ as compared to <0.2/ZZ (all others). However, ON-CD had the highest rates of undefined molecular variants (UMV) (0.16/ZZ) or likely benign variants (LBV) (0.08/ZZ), compared to all others (<0.12/ZZ and < 0.06/ZZ, respectively). The F variant was identified at 0.10/ZZ, only in the ON-CD and the AB-CID protocols. Collectively, MMalton was the next most common variant, identified as a compound heterozygous genotype at 0.04/ZZ, only in the ON-CD and BC-CGID protocols. CONCLUSION: Strategies which readily detect variants across the full coding sequence of SERPINA1 detect more PV as well as more UMV and LBV.