Lithium heparin interference in the Abbott enzymatic creatinine assay: the significance of under-filled tubes.

BACKGROUND: Spuriously high results using the Abbott Architect enzymatic creatinine assay were noted to be particularly associated with very small sample volumes. This led us to query the effect of under-filling lithium heparin tubes on the measured enzymatic creatinine result. METHODS: Blood was provided by 5 laboratory personnel and then decanted into 5 x1.2 mL Sarstedt S-Monovette tubes, giving final blood volumes of 200, 400, 600, 800 and 1200 µL. Plasma was analysed using Abbott Architect Jaffe, enzymatic creatinine, Beckman Coulter (AU500) enzymatic creatinine and Roche (Cobas c702) enzymatic creatinine assays. Saline was also added to Sarstedt 1.2 mL and Teklab 2 mL tubes and analysed using the Abbott Jaffe and enzymatic creatinine methods. RESULTS: Increasing degrees of under-fill were associated with greater over-estimation of creatinine using the Abbott enzymatic assay, but no difference was noted using Jaffe methodology on the same platform or enzymatic assays provided by Roche or Beckman. On average, creatinine was 40.6% (+27.7 µmol/L) higher when only 200 µL of blood was present in the tube. Small volumes of saline added to lithium heparin tubes measured significant creatinine concentrations using the Abbott enzymatic method. CONCLUSIONS: Lithium heparin directly interferes in the Abbott Architect enzymatic creatinine assay. Under-filling lithium heparin tubes can lead to clinically significant over-estimation of creatinine results by this assay. Users of this assay should be aware of the potential for spurious results in small sample volumes collected into lithium heparin tubes and implement robust procedures for identifying and reporting results on these samples.

Implementation of an Automated Primary Care Acute Kidney Injury Warning System: A Quantitative and Qualitative Review of 2 Years of Experience.

BACKGROUND: Acute kidney injury (AKI) is often detected late, leading to worse clinical outcomes. In 2012, we pioneered an AKI-alerting system for primary care clinicians (PCCs). We retrospectively analysed the alerts and evaluated PCC satisfaction to assess the feasibility of the system. METHODS: The study used a 2-pronged approach. AKI alerts, generated by an algorithm designed by University College London Hospital biochemistry department between June 2012 and June 2014, were analysed to reveal the demographics and outcomes of each patient generating an alert. Second, a survey was sent to all PCCs assessing awareness and satisfaction with the service. Simple statistical methods were applied (mean, median, SD and interquartile range). RESULTS: One hundred forty-two alerts were generated, of which 101 were genuine. Generally, the patient demographics, AKI stratification and aetiology were in keeping with the inpatient AKI population. Forty-eight percent of cases were referred to the hospital with a median length of stay of 9.9 days. Three-month mortality was 12%. Among PCCs, there was good awareness of the system with most finding it valuable. The key complaints around the system were to do with lack of knowledge of its existence. CONCLUSIONS: Our evaluation has demonstrated that the implementation of AKI alerts in the community is technically feasible, does not result in excessive demand on hospital services, appears to influence PCC behaviour and was perceived overwhelmingly as a useful service by these clinicians. This experience should inform further developments including behavioural interventions (such as clinician alerts) to improve community AKI care.

ParA-like protein uses nonspecific chromosomal DNA binding to partition protein complexes.

Recent data have shown that plasmid partitioning Par-like systems are used by some bacterial cells to control localization of protein complexes. Here we demonstrate that one of these homologs, PpfA, uses nonspecific chromosome binding to separate cytoplasmic clusters of chemotaxis proteins upon division. Using fluorescent microscopy and point mutations, we show dynamic chromosome binding and Walker-type ATPase activity are essential for cluster segregation. The N-terminal domain of a cytoplasmic chemoreceptor encoded next to ppfA is also required for segregation, probably functioning as a ParB analog to control PpfA ATPase activity. An orphan ParA involved in segregating protein clusters therefore uses a similar mechanism to plasmid-segregating ParA/B systems and requires a partner protein for function. Given the large number of genomes that encode orphan ParAs, this may be a common mechanism regulating segregation of proteins and protein complexes.