Standard -20 °C freezer storage protocols may cause substantial plasma renin cryoactivation.

OBJECTIVES: To assess the appropriate preanalytical process for storage of plasma for renin concentration analysis. This study was initiated due to the wide variation in preanalytical handling of samples observed within our network, particularly with respect to freezing for longer term storage. METHODS: Pooled plasma from patient samples was analysed immediately post separation for renin concentration (n=30, concentration 4.0-204 mIU/L). Aliquots from these samples were frozen in a -20 °C freezer and then analysed, with the renin concentration compared to the respective baseline concentration. Comparisons were also made to: aliquots snap frozen using a dry ice/acetone bath, aliquots stored at room temperature, and aliquots stored at 4 °C. Subsequent experiments investigated the potential sources of cryoactivation observed in these initial studies. RESULTS: Substantial and highly variable cryoactivation was observed in samples frozen using a -20 °C freezer, with renin concentration increasing over 300% from baseline in some samples (median 21.3%). This cryoactivation could be prevented by snap freezing samples. Subsequent experiments determined that long term storage in a -20 °C freezer could prevent cryoactivation provided samples were initially frozen rapidly in a -70 °C freezer. Rapid defrosting of samples was not required to prevent cryoactivation. CONCLUSIONS: Standard -20 °C freezers may not be appropriate for freezing samples for renin analysis. Laboratories should consider snap freezing their samples using a -70 °C freezer or similar to avoid cryoactivation of renin.

Reference intervals for venous blood gas measurement in adults.

OBJECTIVES: Venous blood gas (VBG) analysis is becoming a popular alternative to arterial blood gas (ABG) analysis due to reduced risk of complications at phlebotomy and ease of draw. In lack of published data, this study aimed to establish reference intervals (RI) for correct interpretation of VBG results. METHODS: One hundred and 51 adult volunteers (101 females, 50 males, 18-70 years) were enrolled after completion of a health questionnaire. Venous blood was drawn into safePICO syringes and analysed on ABL827 blood gas analyser (Radiometer Pacific Pty. Ltd.). A non-parametric approach was used to directly establish the VBG RI which was compared to a calculated VBG RI based on a meta-analysis of differences between ABG and VBG. RESULTS: After exclusions, 134 results were used to derive VBG RI: pH 7.30-7.43, partial pressure of carbon dioxide (pCO2) 38-58 mmHg, partial pressure of oxygen (pO2) 19-65 mmHg, bicarbonate (HCO3-) 22-30 mmol/L, sodium 135-143 mmol/L, potassium 3.6-4.5 mmol/L, chloride 101-110 mmol/L, ionised calcium 1.14-1.29 mmol/L, lactate 0.4-2.2 mmol/L, base excess (BE) -1.9-4.5 mmol/L, saturated oxygen (sO2) 23-93%, carboxyhaemoglobin 0.4-1.4% and methaemoglobin 0.3-0.9%. The meta-analysis revealed differences between ABG and VBG for pH, HCO3-, pCO2 and pO2 of 0.032, -1.0 mmol/L, -4.2 and 39.9 mmHg, respectively. Using this data along with established ABG RI, calculated VBG RI of pH 7.32-7.42, HCO3- 23 - 27 mmol/L, pCO2 36-49 mmHg (female), pCO2 39-52 mmHg (male) and pO2 43-68 mmHg were formulated and compared to the VBG RI of this study. CONCLUSIONS: An adult reference interval has been established to assist interpretation of VBG results.

Outcome of adult patients with X-linked hypophosphatemia caused by PHEX gene mutations.

X-linked hypophosphatemia (XLH) is the most common monogenic disorder causing hypophosphatemia. This case-note review documents the clinical features and the complications of treatment in 59 adults (19 male, 40 female) with XLH. XLH is associated with a large number of private mutations; 37 different mutations in the PHEX gene were identified in this cohort, 14 of which have not been previously reported. Orthopaedic involvement requiring surgical intervention (osteotomy) was frequent. Joint replacement and decompressive laminectomy were observed in those older than 40 years. Dental disease (63%), nephrocalcinosis (42%), and hearing impairment (14%) were also common. The rarity of the disease and the large number of variants make it difficult to discern specific genotype-phenotype relationships. A new treatment, an anti-FGF23 antibody, that may affect the natural history of the disease is currently being investigated in clinical trials.

Making sense of a haemolysis monitoring and reporting system: a nationwide longitudinal multimethod study of 68 Australian laboratory participant organisations.

BACKGROUND: The key incident monitoring and management systems (KIMMS) quality assurance program monitors incidents in the pre- and postanalytical phases of testing in medical laboratories. Haemolysed specimens have been found to be the most frequent preanalytical error and have major implications for patient care. The aims of this study were to assess the suitability of KIMMS for quality reporting of haemolysis and to devise a meaningful method for reporting and monitoring haemolysis. METHODS: A structured survey of 68 Australian KIMMS laboratory participant organisations was undertaken. Quarterly haemolysis reports (2011-2014) were analysed. RESULTS: Among 110 million accessions reported, haemolysis rates varied according to the reporting methods that participants used for assigning accessions (16% of participants reported haemolysis by specimen and 83% reported by episode) and counting haemolysis rejections (61% by specimen, 35% by episode and 3% by test). More than half of the participants (56%) assigned accessions by episode and counted rejections by specimen. For this group, the average haemolysis rate per 100,000 episodes was 177 rejected specimens with the average rate varying from 100 to 233 over time. The majority of participants (91%) determined rejections using the haemolysis index. Two thirds of participants (66%) recorded the haemolysis manually in laboratory information systems. CONCLUSIONS: KIMMS maintains the largest longitudinal haemolysis database in the world. However, as a means of advancing improvements in the quality of the preanalytical laboratory process, there is a need to standardise reporting methods to enable robust comparison of haemolysis rejection rates across participant laboratories.

Key factors influencing the incidence of hemolysis: A critical appraisal of current evidence.

Hemolysis is a leading cause of pre-analytical laboratory errors. The identification of contributing factors is an important step towards the development of effective practices to reduce and prevent hemolysis. We performed a review of PUBMED, Embase, Medline and CINAHL to identify articles published between January 2000 and August 2016 that identified factors influencing in vitro hemolysis rates. The 40 studies included in this review provide excellent evidence that hemolysis rates are higher in Emergency Departments (EDs), for non-antecubital draws, for specimens drawn using an intravenous catheter compared to venipuncture and for samples transported by pneumatic tube compared to by hand. There is also good evidence that hemolysis rates are higher when specimens are not collected by professional phlebotomists, larger volume specimen tubes are used, specimen tubes are filled less than halfway and tourniquet time is greater than one minute. The results of this review suggest that hospitals and clinical laboratories should consider deploying phlebotomists in EDs, drawing all blood through a venipuncture, using the antecubital region as the optimum blood collection site and transporting specimens by laboratory assistant/other personnel, or if this in not practical, ensuring that pneumatic transport systems are validated, maintained and monitored. Studies also recommend making hemolysis a hospital-wide issue and ensuring high-quality staff training and adherence to standard operating procedures to reduce hemolysis rates. Awareness of the factors that influence hemolysis rates, and adoption of strategies to mitigate these risk factors, is an important step towards creating quality practices to reduce hemolysis rates and improve the quality of patient care.

The impact of reporting incidental findings from exome and whole-genome sequencing: predicted frequencies based on modeling.

PURPOSE: The American College of Medical Genetics and Genomics released practice guidelines recommending reporting of incidental findings from exome and whole-genome sequencing by massively parallel (next-generation) sequencing for multiple conditions. Policy statements from other agencies are still being developed, and many attempt to take into consideration the predicted increase in workload caused by reporting incidental findings. We describe the effects of changing the sensitivity and the specificity, as well as the implications of varying diagnostic criteria and a priori prevalence, and those of increasing the number of included conditions, on rates of incidental findings. METHODS: We developed a simple mathematical model based on binomial probability for predicting rates of incidental findings. We primed and validated the model using published variant frequencies. RESULTS: The model correctly calculates observed rates of incidental findings. Changing the model's parameters shows that even minor changes in diagnostic criteria or sequencing accuracy cause large variation in rates of incidental findings. CONCLUSION: Our model correctly explains observed rates of incidental findings. Key drivers of rates include diagnostic criteria, variant frequency, disease penetrance, and sequencing and bioinformatics accuracy. Rates of incidental findings are relatively insensitive to even large increases in the number of conditions included.

An effective automated nutrition screen for hospitalized patients.

OBJECTIVE: Screening for malnutrition-related complications (MRCs) in hospitalized patients would identify those requiring nutritional intervention and improve resource allocation. Brugler's simplified screening tool (MRCS) ranks the binary pattern of six readily available variables (categorical cutoff values for serum albumin [<31.5 g/L], lymphocyte count [<1.202 x 10(9)/L], and hemoglobin [<99.5 g/L], the presence of high-risk illness, poor nutritional intake and the presence of a wound) to enable automated computerized screening. This study compared the MRCS with a simpler Automated Nutrition Score (ANS; the number of abnormal results from the six variables) and ANS(B) (the number of abnormal results from the three blood measurements) with the Subjective Global Assessment (SGA) for prediction of complications. METHODS: Of 148 consecutive surgical patients, 143 underwent the SGA on admission. Morbidity was prospectively recorded. The six variables of the MRCS were tabulated and correlated with the frequency of complications. Receiver operating characteristic analysis compared the MRCS with the SGA, ANS, and ANS(B). RESULTS: Twenty-two patients had moderate to severe complications, a pretest probability of 15.3%. Patients stratified as higher risk by the SGA, ANS(B), and ANS had post-test probabilities of complications of 28.7%, 37.8%, and 29.3%, respectively. However, a clinically useful prediction of low risk (post-test probability of 1.5%) was demonstrated when the ANS was

Intravenous amino acid therapy for kidney protection in cardiac surgery patients: A pilot randomized controlled trial.

OBJECTIVE: To determine whether a continuous intravenous infusion of standard amino acids could preserve kidney function after on-pump cardiac surgery. METHODS: Adult patients scheduled to receive cardiac surgery lasting longer than 1 hour on-pump were randomized to standard care (n = 36) or an infusion of amino acids initiated immediately after induction of anesthesia (n = 33). The study's primary outcome measurements assessed renal function. These assessments included duration of renal dysfunction, duration and severity of acute kidney injury (AKI), estimated glomerular filtration rate (eGFR) over time, urine output, and use of renal-replacement therapy. Complications and other measures of morbidity were also assessed. RESULTS: Sixty-nine patients (mean age 71.5 [standard deviation 9.2] years; 19 of 69 women) were enrolled and randomized. Patients received coronary artery bypass graft surgery (37/69), valve surgery (24/69), coronary artery bypass graft and valve surgery (6/69), or other procedures (2/69). Mean on-pump time was 268 [standard deviation 136] minutes. Duration of renal dysfunction did not differ between the groups (relative risk, 0.86; 95% confidence interval [CI], 0.19-3.79, P = .84). However, patients who received the amino acid infusion had a reduced duration of AKI (relative risk, 0.02; 95% CI, 0.005-0.11, P < .0001) and greater eGFR (+10.8%; 95% CI, 1.0%-20.8%, P = .033). Daily mean urine output was also significantly greater in patients who received the amino acid infusion (1.4 ± 0.5 vs 1.7 ± 0.9 L/d; P = .046). CONCLUSIONS: Commencing an infusion of standard amino acids immediately after the induction of anesthesia did not alter duration of renal dysfunction; however, other key measures of renal function (duration of AKI, eGFR and urine output) were significantly improved. These results warrant replication in multicenter clinical trials.

Lot-to-Lot Variation.

Lot-to-lot variation affecting calibrators and reagents is a frequent challenge that limits the laboratory's ability to produce consistent results over time. This variation is not without clinical consequence and there are several well-documented examples of adverse clinical outcomes. It is important that laboratories have procedures in place for quantification of this inaccuracy, and for determining whether the amount of variation is acceptable for the release of patient results. Various approaches have been taken to the assessment of new lots, including the evaluation protocol published by the Clinical and Laboratory Standards Institute (CLSI). Internal quality control and external quality assurance material is often not commutable, and so the use of native patient samples is preferred. Published evaluation protocols differ significantly in ease of use and statistical rigour, and some may be underpowered to detect a clinically meaningful change between lots. Furthermore, current protocols (including the CLSI protocol) will not detect cumulative shifts between reagent lots. This shortcoming may at least partly be addressed by laboratories adopting moving patient averages or similar quality procedures. Collaboration and data-sharing between laboratories and manufacturers also has an important role to play in the detection of lot-to-lot variation. While the laboratory may take steps to evaluate and detect variation, the ideal is to reduce variation between lots at the point of manufacture. Using appropriate acceptance criteria based on medical need or biological variation requirements instead of some arbitrary percentage may go some steps toward achieving this.

Pneumatic tube transport of blood-stained cerebrospinal fluid specimens has no clinically relevant effect on rates of haemolysis compared to manual transport.

BACKGROUND: Pneumatic tube transport of pathology specimens from the emergency department to the laboratory for analysis is a widely used practice. When compared to manual specimen transport, it results in savings in both time and labour. Sampling of cerebrospinal fluid still forms part of the workup of patients with suspected subarachnoid haemorrhage. There are claims in the literature that transport of cerebrospinal fluid samples by pneumatic tube results in excess haemolysis, which interferes with cerebrospinal fluid analysis for the presence of bilirubin. The aim of our study was to ascertain whether pneumatic tube transport of blood-stained cerebrospinal fluid to the laboratory, results in clinically significantly higher levels of haemolysis compared with manual transport of the same specimens. METHODS: Stored cerebrospinal fluid was spiked with varying amounts of red blood cells creating 72 specimens of varying red cell concentration. Half of these specimens were transported to the laboratory manually while the other half were sent by pneumatic tube transport. The rates of haemolysis were compared between the pneumatic tube and manual transport samples. RESULTS: There was no clinically significant difference in the rates of haemolysis between the samples transported to the laboratory by pneumatic tube compared with those moved manually. CONCLUSIONS: Pneumatic tube transport of cerebrospinal fluid to the laboratory is not associated with clinically significantly higher rates of haemolysis when compared to manual transport.

Current Methods of Haemolysis Detection and Reporting as a Source of Risk to Patient Safety: a Narrative Review.

AIM: Haemolysis has a major impact on patient safety as the need for a replacement specimen increases the risk of injury and infection, delays test results and extends the duration of hospital stays. Consistency of haemolysis detection and reporting can facilitate the generation of benchmark data used to develop quality practices to monitor and reduce this leading cause of pre-analytical laboratory error. This review aims to investigate current methods of haemolysis detection and reporting. METHOD: Due to known heterogeneity and immaturity of the research field, a scoping search was conducted using PUBMED, Embase, Medline and CINAHL. Articles published between 2000 and 2014 that reported haemolysis rates in specimens from the general population were included. RESULTS: Of the 50 studies that met the inclusion criteria, 20 detected haemolysis using the Haemolysis Index (HI), 19 by visual inspection and 13 by undefined methods. There was large intra-study variation in the plasma free haemoglobin level used to establish haemolysis (HI: mean±SD 846±795 mg/L, range 150-3000 mg/L; Visual: 850±436 mg/L, 500-3000 mg/L). Sixteen studies reported the analyte of interest, with only three studies reporting a haemoglobin level at which the specimen would be rejected. CONCLUSION: Despite haemolysis being a frequent and costly problem with a negative impact on patient care, there is poor consistency in haemolysis detection and reporting between studies. Improved consistency would facilitate the generation of benchmark data used to create quality practices to monitor and reduce this leading cause of pre-analytical laboratory error.

Should serum pancreatic lipase replace serum amylase as a biomarker of acute pancreatitis?

BACKGROUND: Serum pancreatic lipase may improve the diagnosis of pancreatitis compared to serum amylase. Both enzymes have been measured simultaneously at our hospital allowing for a comparison of their diagnostic accuracy. METHODS: Seventeen thousand five hundred and thirty-one measurements of either serum amylase and or serum pancreatic lipase were made on 10 931 patients treated at a metropolitan teaching hospital between January 2001 and May 2003. Of these, 8937 were initially treated in the Emergency Department. These results were collected in a database, which was linked by the patients' medical record number to the radiology and medical records. Patients with either an elevated lipase value or a discharge diagnosis of acute pancreatitis had their radiological diagnosis reviewed along with their biochemistry and histology record. The diagnosis of acute pancreatitis was made if there was radiological evidence of peripancreatic inflammation. RESULTS: One thousand eight hundred and twenty-five patients had either elevated serum amylase and or serum pancreatic lipase. The medical records coded for pancreatitis in a further 55 whose enzymes were not elevated. Three hundred and twenty of these had radiological evidence of acute pancreatitis. Receiver operator characteristic analysis of the initial sample from patients received in the Emergency Department showed improved diagnostic accuracy for serum pancreatic lipase (area under the curve (AUC) 0.948) compared with serum amylase (AUC, 0.906, P < 0.05). A clinically useful cut-off point would be at the diagnostic threshold; 208 U/L (normal <190 U/L) for serum pancreatic lipase and 114 U/L (normal 27-100 U/L) for serum amylase where the sensitivity was 90.3 cf., 76.8% and the specificity was 93 cf., 92.6%. 18.8% of the acute pancreatitis patients did not have elevated serum amylase while only 2.9% did not have elevated serum pancreatic lipase on the first emergency department measurement. CONCLUSION: It is concluded that serum pancreatic lipase is a more accurate biomarker of acute pancreatitis than serum amylase.

Restricted versus continued standard caloric intake during the management of refeeding syndrome in critically ill adults: a randomised, parallel-group, multicentre, single-blind controlled trial.

BACKGROUND: Equipoise exists regarding the benefits of restricting caloric intake during electrolyte replacement for refeeding syndrome, with half of intensive care specialists choosing to continue normal caloric intake. We aimed to assess whether energy restriction affects the duration of critical illness, and other measures of morbidity, compared with standard care. METHODS: We did a randomised, multicentre, single-blind clinical trial in 13 hospital intensive care units (ICUs) in Australia (11 sites) and New Zealand (two sites). Adult critically ill patients who developed refeeding syndrome within 72 h of commencing nutritional support in the ICU were enrolled and allocated to receive continued standard nutritional support or protocolised caloric restriction. 1:1 computer-based randomisation was done in blocks of variable size, stratified by enrolment serum phosphate concentration (>0·32 mmol/L vs ≤0·32 mmol/L) and body-mass index (BMI; >18 kg/m(2)vs ≤18 kg/m(2)). The primary outcome was the number of days alive after ICU discharge, with 60 day follow-up, in a modified intention-to-treat population of all randomly allocated patients except those mistakenly enrolled. Days alive after ICU discharge was a composite outcome based on ICU length of stay, overall survival time, and mortality. The Refeeding Syndrome Trial was registered with the Australian and New Zealand Clinical Trials Registry (ANZCTR number 12609001043224). FINDINGS: Between Dec 3, 2010, and Aug 13, 2014, we enrolled 339 adult critically ill patients: 170 were randomly allocated to continued standard nutritional support and 169 to protocolised caloric restriction. During the 60 day follow-up, the mean number of days alive after ICU discharge in 165 assessable patients in the standard care group was 39·9 (95% CI 36·4-43·7) compared with 44·8 (95% CI 40·9-49·1) in 166 assessable patients in the caloric restriction group (difference 4·9 days, 95% CI -2·3 to 13·6, p=0·19). Nevertheless, protocolised caloric restriction improved key individual components of the primary outcome: more patients were alive at day 60 (128 [78%] of 163 vs 149 [91%] of 164, p=0·002) and overall survival time was increased (48·9 [SD 1·46] days vs 53·65 [0·97] days, log-rank p=0·002). INTERPRETATION: Protocolised caloric restriction is a suitable therapeutic option for critically ill adults who develop refeeding syndrome. We did not identify any safety concerns associated with the use of protocolised caloric restriction. FUNDING: National Health and Medical Research Council of Australia.

Intravenous amino acid therapy for kidney function in critically ill patients: a randomized controlled trial.

IMPORTANCE: Acute kidney injury (AKI) is characterized by severe loss of glomerular filtration rate (GFR) and is associated with a prolonged intensive care unit (ICU) stay and increased risk of death. No interventions have yet been shown to prevent AKI or preserve GFR in critically ill patients. Evidence from mammalian physiology and small clinical trials suggests higher amino acid intake may protect the kidney from ischemic insults and thus may preserve GFR during critical illness. OBJECTIVE: To determine whether amino acid therapy, achieved through daily intravenous (IV) supplementation with standard amino acids, preserves kidney function in critically ill patients. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, phase II, randomized clinical trial conducted between December 2010 and February 2013 in the ICUs of 16 community and tertiary hospitals in Australia and New Zealand. Participants were adult critically ill patients expected to remain in the study ICU for longer than 2 days. INTERVENTIONS: Random allocation to receive a daily supplement of up to 100 g of IV amino acids or standard care. MAIN OUTCOMES AND MEASURES: Duration of renal dysfunction (primary outcome); estimated GFR (eGFR) derived from creatinine; eGFR derived from cystatin C; urinary output; renal replacement therapy (RRT) use; fluid balance and other measures of renal function. RESULTS: 474 patients were enrolled and randomized (235 to standard care, 239 to IV amino acid therapy). At time of enrollment, patients allocated to receive amino acid therapy had higher APACHE II scores (20.2 ± 6.8 vs. 21.7 ± 7.6, P = 0.02) and more patients had pre-existing renal dysfunction (29/235 vs. 44/239, P = 0.07). Duration of renal dysfunction after enrollment did not differ between groups (mean difference 0.21 AKI days per 10 patient ICU days, 95 % CI -0.27 to 1.04, P = 0.45). Amino acid therapy significantly improved eGFR (treatment group × time interaction, P = 0.004), with an early peak difference of 7.7 mL/min/1.73 m(2) (95 % CI 1.0-14.5 mL/min/1.73 m(2), P = 0.02) on study day 4. Daily urine output was also significantly increased (+300 mL/day, 95 % CI 145-455 mL, P = 0.0002). There was a trend towards increased RRT use in patients receiving amino acid therapy (13/235 vs. 25/239, P = 0.062); however, this trend was not present after controlling for baseline imbalance (P = 0.21). CONCLUSION AND RELEVANCE: Treatment with a daily IV supplement of standard amino acids did not alter our primary outcome, duration of renal dysfunction. TRIAL REGISTRATION: anzctr.org.au Identifier: ACTRN12609001015235.

Improving the quality of information on pathology request forms.

BACKGROUND: We have investigated the causes of incomplete pathology request forms received at our clinical chemistry laboratory. Based on a request form audit we found that the data most frequently missing from a pathology request form was the doctor's name, unique identification provider number, or signature. METHODS: We examined the effect of issuing the requesting doctors with self-inking stamps personalized with their name and a unique provider number. RESULTS: The intervention led to an immediate and sustained improvement in compliance, with the proportion of incomplete forms falling from 43% to 2%. In contrast, distribution of a memorandum alone made no significant change to the number of pathology request forms with incomplete data arriving at the laboratory. CONCLUSION: This study describes a simple and low-cost solution to one of the causes of incomplete pathology request forms. It also demonstrates the effectiveness of systems improvement in health care.

Optimizing the availability of 'stat' laboratory tests using Shewhart 'C' control charts.

BACKGROUND: We describe a general strategy for optimizing the availability of 'stat' out-of-hours laboratory tests to the particular clinical needs of health care institutions. METHODS: We initially introduced a consensus menu of 'stat' tests and prospectively monitored for 5 years all additional requests for 'stat' clinical biochemistry tests in a metropolitan tertiary referral university teaching hospital. Laboratory staff triaged 'stat' requests, and clinical biochemistry consultants reviewed requests not already performed routinely. The frequency of these requests was monitored on a Shewhart 'c' control chart. A quality system certified to ISO 9001 was used to assure laboratory compliance with procedures. Various interventions were tested using the Shewhart 'c' control chart to monitor their effectiveness. RESULTS: Matching the timing of analytical assays with the time of sample collection had no significant effect on the number of 'stat' requests. Implementation of a hospital-wide laboratory information system also had no significant effect on the number of 'stat' requests. The most effective strategy consisted of optimization of the test menu to match request patterns, combined with the introduction of a laboratory quality system. CONCLUSIONS: Within our institution, this strategy resulted in a sevenfold reduction in 'stat' requests, from one per 2,200 specimens to fewer than one per 32,000 specimens.

Evaluating assay precision.

* When evaluating the precision of a method it is necessary to assess the repeatability (within-run) and the total or within-laboratory precision. * It is insufficient to assess repeatability in a single run. * Clinical and Laboratory Standards Institute (CLSI) document EP05-A2 describes the protocols for determining the precision of a method. The precision of a method should be tested at at-least two levels; each run in duplicate, with two runs per day over 20 days. CLSI document EP15-A2 describes the protocols that should be undertaken by the user to verify precision claims by a manufacturer. Precision claims by a manufacturer should be tested at at-least two levels, by running three replicates over five days. * A spreadsheet for assisting with the calculations described in this article is available from the AACB web-site.