Synovial neutrophilic gelatinase-associated lipocalin in the diagnosis of periprosthetic joint infection after total knee arthroplasty.

BACKGROUND: Periprosthetic joint infection (PJI) is one of the most serious complications following total knee arthroplasty (TKA). However, the diagnosis remains a challenge for clinicians. In 2011, the muscoskeletal infection society (MSIS) criteria provided a consensus which has been updated in 2013, but these criteria are complex and contain tests that are time-consuming. The same is applicable to the pro-Implant guidelines. Therefore, a simpler diagnostic test is desirable. OBJECTIVES: The value of neutrophil gelatinase-associated lipocalin (NGAL), leucocyte esterase (LE) levels, and the white blood cell (WBC) count in synovial fluid to diagnose PJI after TKA was evaluated. METHODS: In a retrospective cohort study, we analyzed 89 synovial fluid samples from 86 patients with suspected PJI after TKA. Thirteen and 23 of those samples were classified as PJI according to the MSIS and pro-Implant criteria, respectively. Subsequently, NGAL, LE levels, and the WBC count were determined, the former one using an immunoassay. Using either the MSIS or pro-Implant criteria as the golden standard for PJI, sensitivity and specificity of those markers were determined with ROC curves, and medians were compared with Mann-Whitney U and Pearson Chi-square tests. RESULTS: When applying the MSIS criteria, NGAL revealed 92% sensitivity and 83% specificity. WBC count showed similar sensitivity (92%) and specificity (84%), whereas sensitivity and specificity for LE were 39% and 88% respectively. When applying the pro-Implant criteria, sensitivity was 95% and specificity was 95% for NGAL. Sensitivity and specificity for WBC count were 100% and 97% and for LE 39% and 92% respectively. CONCLUSION: NGAL and WBC count in synovial fluid has high accuracy in the diagnosis of PJI after TKA and should seriously be considered as part of PJI diagnostics. Leucocyte esterase can serve as rule-in criterion peroperatively. These conclusions are independent of which criteria set was used as golden standard.

Oral Tobramycin Prophylaxis Prior to Colorectal Surgery Is Not Associated with Systemic Uptake.

Preoperative oral prophylaxis with nonabsorbable antibiotics has been reported to reduce the risk of surgical site infections after colorectal surgery. This prospective study was conducted to evaluate the risk of toxic side effects by measuring postoperative serum tobramycin levels in patients who received a 3-day prophylaxis with tobramycin and colistin prior to colorectal surgery. In all patients, serum tobramycin concentrations were below the detection limit (0.3 mg/liter), implying a low risk of toxicity.

[A neonate with umbilical cord bleeding]. / Een neonaat met een navelstompbloeding.

A 7-day-old neonate was admitted to our neonatal ward for umbilical stump bleeding. His medical history included hyperbilirubinaemia due to cephalic haematoma. Only after the administration of fresh frozen plasma, the bleeding stopped, suggesting coagulation factor deficiency. Elaborate coagulation tests showed factor XIII-deficiency.

Factor XIII deficiency: complete phenotypic characterization of two cases with novel causative mutations.

Coagulation factor XIII (FXIII) exists as heterotetramer (FXIII-A2B2) in the plasma and as dimer (FXIII-A2) in cells. Activated FXIII mechanically stabilizes fibrin and protects it from fibrinolysis by cross-linking fibrin chains and α2-plasmin inhibitor to fibrin. FXIII is essential to maintaining haemostasis, and its deficiency causes severe bleeding diathesis. Due to improper laboratory practices, FXIII deficiency is considered the most under-diagnosed bleeding disorder. The aim of this study was to demonstrate in two cases how FXIII deficiency is properly diagnosed and classified, and to compare results of laboratory analysis and clinical symptoms. FXIII activity from plasma and platelets was measured by a modified ammonia release assay, while FXIII-A2B2, FXIII-A and FXIII-B antigens were determined by ELISA. The exon-intron boundaries and the promoter region of F13A1 gene were amplified by PCR and the amplified products were analysed by direct fluorescent sequencing. FXIII-A mRNA in platelets was determined by RT-qPCR. Two children with severe bleeding symptoms were investigated. In both cases FXIII activity and FXIII-A antigen were undetectable in the plasma and platelet lysate. In the plasma no FXIII-A2B2 antigen was found, while FXIII-B antigen was >30% in both cases. Proband1 was a compound heterozygote possessing a known missense mutation (c.980G>A, p.Arg326Gln) and a novel splice-site mutation (c.1112+2T>C). Proband2 was homozygote for a novel single nucleotide deletion (c.212delA) leading to early stop codon. The discovered mutations explain the severity of clinical symptoms and the laboratory data. Methods precise in the low activity/antigen range are required to draw valid conclusion on phenotype-genotype relationship.

Iron autointoxication in a 16-year-old girl: a protective role for hepcidin?

Intentional iron overdose appears to be an increasingly common form of attempted suicide. We present a case of iron overdose in a 16-year-old girl who was found unconscious in her bed and brought to our emergency department. The most remarkable diagnostic findings were the patient's comatose condition, divergent eye position and positive Babinski foot pad reflexes. Laboratory tests showed hyperglycaemia and mild metabolic acidosis. A computed tomography scan of the cerebrum showed no signs of intracerebral haemorrhage or elevated intracerebral pressure. Toxicology screening showed no use of acetaminophen, ethanol or drugs of abuse. The patient was stabilized and monitored on the intensive care ward. When she woke up, she confessed to having taken Fero-Gradumet(®). Retrospectively analysed, the serum iron concentration in the first blood sample (seven hours after ingestion) was 62 µmol/L which corresponds with moderate iron intoxication. The patient received whole bowel irrigation with 2 L polyethyleneglycol solution and de-ironing treatment with intravenous deferoxamine 20 mg/kg in eight hours. She was discharged from the hospital after three days in a good clinical condition. Retrospectively, serum hepcidin concentrations were determined and evaluated in conjunction with serum iron concentrations and the installed treatment. Before medical de-ironing interventions were started, we saw that the serum iron concentration in our patient was already declining. At the same time, we observed a sharp increase in the serum hepcidin concentration. After normalization of serum iron concentrations, hepcidin normalized as well.

New erythrocyte and reticulocyte parameters on CELL-DYN Sapphire: analytical and preanalytical aspects.

INTRODUCTION: Extended RBC and reticulocyte parameters are useful in diagnosing functional iron deficiency and various other clinical conditions. The newest software of the CELL-DYN Sapphire measures extended RBC and reticulocyte parameters. The aims of the present communication were to assess the analytical aspects of these parameters compared with the Siemens Advia 120 analyzer, to study the effect of sample aging and to briefly explore their clinical usefulness in patients with anemia. METHODS: Blood samples were obtained from the routine workload of two hospital laboratories and were run on Siemens Advia and Abbott CELL-DYN Sapphire analyzers in parallel. Data analysis was performed using standard statistics. RESULTS: In total, 1416 patient samples were analyzed. There was close correlation in microcytic and macrocytic RBC (r(2) > 0.97) with small bias. The hypo- and hyperchromic RBC showed reasonable correlations, Advia 120 giving higher values. Reticulocyte MCV showed acceptable agreement, with significant proportional bias (Advia 8-9% higher). CELL-DYN Sapphire MCHr correlated rather well with Advia CHr (r(2) > 0.91) with significant absolute bias. Remarkably, the correlation data differed significantly between the two laboratories. It was found that aging of EDTA samples had significant effect on most of the RBC parameters. CONCLUSIONS: The new RBC parameters of CELL-DYN Sapphire generally correlated well with those of Advia 120, although significant systematic differences were present, particularly in reticulocyte MCH and MCV. These differences necessitate instrument-specific reference ranges and clinical decision values. To minimize preanalytical effects, these parameters should be measured in fresh blood samples.

Quality control of bone marrow cytology; organization and over 7 years experience in the south-west Netherlands.

To asses the quality of bone marrow cytology of hospital laboratories in the south-west Netherlands a proficiency testing program was implemented. Two sets of bone marrow and blood smears from two patients were sent to 20 hospital laboratories using a tight time schedule biannually. Required results consisted of differential counts of 500 bone marrow cells and 100 peripheral blood cells, together with the description of morphological abnormalities and final conclusions. Twice a year the collected review data were discussed in a plenary session which was also used for continuous education. Over the past 7 years 30 bone marrow samples were evaluated. The coefficient of variations of specific cells counts was large. The amount of correct conclusions ranged from 12% to 100% (median: 61%). Participant attendance of the meetings was 90-100%. The total cost of this scheme of proficiency testing approximately amounted euro7000 per year. The presented formulae for both proficiency testing and haematopathological/cytological education is feasible and fulfilled the need of the participants.

Haemolytic disease of the newborn because of rare anti-Vel.

Routine screening for maternal immunization in a 36-year-old woman revealed an alloimmunization against the high-incidence Vel antigen during a second pregnancy. Because of the development of immunoglobulin G-type anti-Vel, the infant developed haemolytic disease of the newborn, with severe jaundice and reticulocytosis. Phototherapy was needed to reduce hyperbilirubinaemia.

Fresh frozen plasma transfusion for reversal of prolonged post-anaesthesia apnoea.

An 18-year old woman admitted for tonsillectomy developed prolonged post-operative paralysis after anaesthesia with mivacurium. Investigation revealed a decreased cholinesterase activity because of a homozygous atypical and heterozygous K variant of the cholinesterase gene. Transfusion of fresh frozen plasma was associated with reversal of the respiratory paralysis and complete recovery.

Significance of elevated cobalamin (vitamin B12) levels in blood.

Elevated levels of serum cobalamin may be a sign of a serious, even life-threatening, disease. Hematologic disorders like chronic myelogeneous leukemia, promyelocytic leukemia, polycythemia vera and also the hypereosinophilic syndrome can result in elevated levels of cobalamin. Not surprisingly, a rise of the cobalamin concentration in serum is one of the diagnostic criteria for the latter two diseases. The increase in circulating cobalamin levels is predominantly caused by enhanced production of haptocorrin. Several liver diseases like acute hepatitis, cirrhosis, hepatocellular carcinoma and metastatic liver disease can also be accompanied by an increase in circulating cobalamin. This phenomenon is predominantly caused by cobalamin release during hepatic cytolysis and/or decreased cobalamin clearance by the affected liver. Altogether it can be concluded that an observed elevation of cobalamin in blood merits the a full diagnostic work up to assess the presence of disease.

[The significance of an elevated cobalamin concentration in the blood]. / De betekenis van een te hoge cobalamineconcentratie in het bloed.

Elevated levels of serum cobalamin may be a sign of a serious, even life-threatening, disease. Diseases such as chronic myeloid leukaemia, promyelocytic leukaemia, polycythaemia vera and hypereosinophilic syndrome are often accompanied by markedly elevated levels of cobalamin in the blood. A rise in the serum cobalamin concentration is one of the diagnostic criteria for polycythaemia vera and hypereosinophilic syndrome. In haematological disorders, the increase in circulating cobalamin levels is predominantly caused by enhanced production of haptocorrin. Several liver diseases such as acute hepatitis, cirrhosis of the liver, hepatocellular carcinoma and metastatic liver disease can also be accompanied by an increase in circulating cobalamin. In liver diseases, the increase in cobalamin is predominantly caused by cobalamin release during hepatic cytolysis and/or through decreased clearance of circulating cobalamin by the affected liver. Liver disorders are not an indication for determining the serum cobalamin concentration. However, a coincidentally observed elevated serum cobalamin concentration is reason for further investigation.