The impact of between analytical platform variability on the classification of pleural effusions into exudate or transudate using Light's criteria

BACKGROUND

Light's criteria are ratios of pleural fluid to serum total protein (TP), pleural fluid to serum lactate dehydrogenase (LDH) and pleural fluid LDH to the upper reference limit for serum LDH. They are used to classify pleural effusions into an exudate or transudate when pleural fluid protein is 25-35 g/L. We evaluated the impact of between analytical platforms on the classification of pleural effusions using Light's criteria.

METHODS

Light's criteria were used to classify pleural effusions with fluid TP between 25 and 35 g/L into exudate and transudate. LDH and TP were analysed using an Abbott ARCHITECT c16000 analyser using a lactate to pyruvate method for LDH and two Roche Cobas 800 c702 analysers, one using a lactate to pyruvate method (laboratory B) and one a lactate to pyruvate method (laboratory C).

RESULTS

Eighty-three paired serum and pleural fluid samples were analysed. Of these, 44 samples had a pleural fluid TP between 25 and 35 g/L and were classified according to Light's criteria. Classification of pleural fluid into transudate or exudate using different analytical platforms was 82% concordant. The LDH ratio and TP ratio were similar in laboratory B and laboratory C, but these were respectively lower (p<0.001) and higher (p<0.001) than those at laboratory A.

CONCLUSIONS

Although Light's criteria are ratios, which should minimise interassay variability, we report 18% discordance between different analytical platforms. The discordance was largely due to the performance of LDH and to a lesser extent protein assays in pleural fluid. Laboratories should be aware that assays may perform differently in serum and pleural fluid.

Multicentre validation of a microRNA-based assay for diagnosing indeterminate thyroid nodules utilising fine needle aspirate smears

AIMS

The distinction between benign and malignant thyroid nodules has important therapeutic implications. Our objective was to develop an assay that could classify indeterminate thyroid nodules as benign or suspicious, using routinely prepared fine needle aspirate (FNA) cytology smears.

METHODS

A training set of 375 FNA smears was used to develop the microRNA-based assay, which was validated using a blinded, multicentre, retrospective cohort of 201 smears. Final diagnosis of the validation samples was determined based on corresponding surgical specimens, reviewed by the contributing institute pathologist and two independent pathologists. Validation samples were from adult patients (≥18 years) with nodule size >0.5 cm, and a final diagnosis confirmed by at least one of the two blinded, independent pathologists. The developed assay, RosettaGX Reveal, differentiates benign from malignant thyroid nodules, using quantitative RT-PCR.

RESULTS

Test performance on the 189 samples that passed quality control: negative predictive value: 91% (95% CI 84% to 96%); sensitivity: 85% (CI 74% to 93%); specificity: 72% (CI 63% to 79%). Performance for cases in which all three reviewing pathologists were in agreement regarding the final diagnosis (n=150): negative predictive value: 99% (CI 94% to 100%); sensitivity: 98% (CI 87% to 100%); specificity: 78% (CI 69% to 85%).

CONCLUSIONS

A novel assay utilising microRNA expression in cytology smears was developed. The assay distinguishes benign from malignant thyroid nodules using a single FNA stained smear, and does not require fresh tissue or special collection and shipment conditions. This assay offers a valuable tool for the preoperative classification of thyroid samples with indeterminate cytology.

HPV self-sampling in CIN2+ detection: sensitivity and specificity of different RLU cut-off of HC2 in specimens from 786 women

AIMS

Mortality for cervical cancer varies between the different regions of the world, with high rates in low-income countries where screening programmes are not present and organised. However, increasing screening coverage is still a priority in all countries: one way to do that is to base screening on self-sampled screening. The success of a self-sampling screening strategy depends on capacity to recruit unscreened women, on the performance and acceptability of the device and on the clinical performance of the high-risk human papillomavirus (HPV) test.

METHODS

This study based on 786 enrolled women investigates the best cut-off value of Hybrid Capture 2 HPV test (HC2) for self-sampled specimens in terms of sensitivity and specificity.

RESULTS

In this population, we found that the sensitivity and the specificity for cervical intraepithelial neoplasia grade 2 or more detection of HC2 performed on self-sampled specimens were 82.5% and 82.8%, respectively considering the relative light units (RLU) cut-off value of 1. Increasing the cut-off value the sensitivity decreases and the specificity raises and the best area under the curve for the RLU cut-off value is 1.

CONCLUSIONS

Our results confirm that the cut-off value of 1 suggested by Qiagen for PreservCyt specimen is the best cut-off value also for self-sampled specimens.

Development and in-use evaluation of a novel Luminex MicroPlex microsphere-based (TRIOL) assay for simultaneous identification of Mycobacterium tuberculosis and detection of first-line and second-line anti-tuberculous drug resistance in China

AIMS

Rapid and accurate diagnostic assays with simultaneous microbial identification and drug resistance detection are essential for optimising treatment and control of tuberculosis.

METHODS

We developed a novel multiplex (TRIOL, Tuberculosis-Rifampicin-Isoniazid-Ofloxacin-Luminex) assay using the Luminex xMAP system that simultaneously identifies Mycobacterium tuberculosis and detects resistance to first-line and second-line anti-tuberculous drugs, and compared its performance with that by PCR sequencing, using phenotypic drug susceptibility testing as the gold standard.

RESULTS

Identification of M. tuberculosis by the TRIOL assay was highly sensitive (100%) and specific (100%). The overall drug-specific specificities were excellent (100%). The overall sensitivity of the TRIOL assay was lower than that of the PCR-sequencing assays (72.4% vs 82.8%) because of a lower sensitivity of detecting rifampicin resistance (71.4% vs 92.9%). The sensitivity of detecting isoniazid and ofloxacin resistance was as good as the PCR-sequencing assays. Importantly, the TRIOL assay did not miss any mutations that were included in the assay. All of the resistant isolates that were missed had uncommon mutations or unknown resistance mechanisms that were not included in the assay.

CONCLUSIONS

The TRIOL assay has higher throughput, lower cost and is less labour intensive than the PCR-sequencing assays. The TRIOL assay is advantageous in having the capability to detect resistance to multiple drugs and an open-architecture system that allows addition of more specific primers to detect uncommon mutations. Inclusion of additional primers for the identification of non-tuberculous mycobacteria, spoligotyping and improvement of rifampicin resistance detection would enhance the use of the TRIOL assay in future clinical and epidemiological studies.

Validation of a locally derived serum calcium adjustment equation: relationship with total 25(OH) vitamin D and PTH levels

AIMS

Many clinical laboratories in the UK use a standard equation to adjust total calcium for albumin concentration. To assess the validity of this practice, we assessed the effect of the use of a traditional and locally derived calcium adjustment equation on parathyroid hormone (PTH) and 25(OH, hydroxy) vitamin D levels.

METHODS

Samples requested for calcium and albumin measurement over a 6 month period that met inclusion criteria were used to derive a calcium adjustment equation (n=60 941). The traditional and locally derived calcium adjustment equations were then applied to a second cohort of adult patients that underwent calcium measurement over a 1 year period (n=275 456). Patients were classified as hypocalcaemic, normocalcaemic or hypercalcaemic using a UK Pathology Harmony adjusted calcium reference interval (2.2-2.6 mmol/L).

RESULTS

The local calcium adjustment equation provided a 7.1-fold reduction in the prevalence of hypocalcaemia. Patients classified as hypocalcaemic using the locally derived equation had statistically significantly lower 25(OH) vitamin D and higher PTH levels. A 2.4-fold increase in the prevalence of hypercalcaemia was also observed using the new equation, but with no significant difference in 25(OH) vitamin D or PTH levels.

CONCLUSIONS

A locally derived calcium adjustment equation reclassified the calcium status of 61 278 (22%) patients. Patients classified as hypocalcaemic by the locally derived equation had significantly lower 25(OH) vitamin D and significantly higher PTH values, providing evidence that use of this adjustment equation generates adjusted calcium results of greater clinical relevance. This study provides further and novel evidence that individual laboratories should determine local equations for adjusted calcium where possible.

Laboratory assessment of vitamin B12 status

The detection and correction of vitamin B₁₂ (B₁₂) deficiency prevents megaloblastic anaemia and potentially irreversible neuropathy and neuropsychiatric changes. B₁₂ status is commonly estimated using the abundance of the vitamin in serum, with ∼148 pmol/L (200 ng/L) typically set as the threshold for diagnosing deficiency. Serum B₁₂ assays measure the sum of haptocorrin-bound and transcobalamin-bound (known as holotranscobalamin) B₁₂ It is only holotranscobalamin that is taken up by cells to meet metabolic demand. Although receiver operator characteristic curves show holotranscobalamin measurement to be a moderately more reliable marker of B₁₂ status than serum B₁₂, both assays have an indeterminate range. Biochemical evidence of metabolic abnormalities consistent with B₁₂ insufficiency is frequently detected despite an apparently sufficient abundance of the vitamin. Laboratory B₁₂ status markers that reflect cellular utilisation rather than abundance are available. Two forms of B₁₂ act as coenzymes for two different reactions. Methionine synthase requires methylcobalamin for the remethylation of methionine from homocysteine. A homocysteine concentration >20 µmol/L may suggest B₁₂ deficiency in folate-replete patients. In the second B₁₂-dependent reaction, methylmalonyl-CoA mutase uses adenosylcobalamin to convert methylmalonyl-CoA to succinyl-CoA. In B₁₂ deficiency excess methylmalonyl-CoA is hydrolysed to methylmalonic acid. A serum concentration >280 nmol/L may suggest suboptimal status in young patients with normal renal function. No single laboratory marker is suitable for the assessment of B₁₂ status in all patients. Sequential assay selection algorithms or the combination of multiple markers into a single diagnostic indicator are both approaches that can be used to mitigate inherent limitations of each marker when used independently.

Pre-trial inter-laboratory analytical validation of the FOCUS4 personalised therapy trial

INTRODUCTION

Molecular characterisation of tumours is increasing personalisation of cancer therapy, tailored to an individual and their cancer. FOCUS4 is a molecularly stratified clinical trial for patients with advanced colorectal cancer. During an initial 16-week period of standard first-line chemotherapy, tumour tissue will undergo several molecular assays, with the results used for cohort allocation, then randomisation. Laboratories in Leeds and Cardiff will perform the molecular testing. The results of a rigorous pre-trial inter-laboratory analytical validation are presented and discussed.

METHODS

Wales Cancer Bank supplied FFPE tumour blocks from 97 mCRC patients with consent for use in further research. Both laboratories processed each sample according to an agreed definitive FOCUS4 laboratory protocol, reporting results directly to the MRC Trial Management Group for independent cross-referencing.

RESULTS

Pyrosequencing analysis of mutation status at KRAS codons12/13/61/146, NRAS codons12/13/61, BRAF codon600 and PIK3CA codons542/545/546/1047, generated highly concordant results. Two samples gave discrepant results; in one a PIK3CA mutation was detected only in Leeds, and in the other, a PIK3CA mutation was only detected in Cardiff. pTEN and mismatch repair (MMR) protein expression was assessed by immunohistochemistry (IHC) resulting in 6/97 discordant results for pTEN and 5/388 for MMR, resolved upon joint review. Tumour heterogeneity was likely responsible for pyrosequencing discrepancies. The presence of signet-ring cells, necrosis, mucin, edge-effects and over-counterstaining influenced IHC discrepancies.

CONCLUSIONS

Pre-trial assay analytical validation is essential to ensure appropriate selection of patients for targeted therapies. This is feasible for both mutation testing and immunohistochemical assays and must be built into the workup of such trials.

TRIAL REGISTRATION NUMBER

ISRCTN90061564.

Comparative evaluation of matrix-assisted laser desorption ionisation-time of flight mass spectrometry and conventional phenotypic-based methods for identification of clinically important yeasts in a UK-based medical microbiology laboratory

AIMS

Performance of matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) was compared in a side-by side-analysis with conventional phenotypic methods currently in use in our laboratory for identification of yeasts in a routine diagnostic setting.

METHODS

A diverse collection of 200 clinically important yeasts (19 species, five genera) were identified by both methods using standard protocols. Discordant or unreliable identifications were resolved by sequencing of the internal transcribed spacer region of the rRNA gene.

RESULTS

MALDI-TOF and conventional methods were in agreement for 182 isolates (91%) with correct identification to species level. Eighteen discordant results (9%) were due to rarely encountered species, hence the difficulty in their identification using traditional phenotypic methods.

CONCLUSIONS

MALDI-TOF MS enabled rapid, reliable and accurate identification of clinically important yeasts in a routine diagnostic microbiology laboratory. Isolates with rare, unusual or low probability identifications should be confirmed using robust molecular methods.

Reticulocyte parameters of delta beta thalassaemia trait, beta thalassaemia trait and iron deficiency anaemia

AIMS

To analyse the differences in reticulocyte indices between delta beta thalassaemia trait (δβ-TT), beta thalassaemia trait (β-TT) and iron deficiency anaemia (IDA), and to correlate those differences with the physiopathological features of these three types of microcytoses.

METHODS

We performed a descriptive study of 428 samples (43 δβ-TT, 179 β-TT and 206 IDA) that were run on Advia 2120 analyser (Siemens). The following reticulocyte indices were assessed: absolute reticulocyte count (ARC), percentage of reticulocytes, mean corpuscular volume of reticulocytes (MCVr), haemoglobin content of reticulocytes (CHr), mean corpuscular haemoglobin concentration of reticulocytes, red blood cell distribution width of reticulocytes (RDWr), haemoglobin distribution width of reticulocytes (HDWr) and reticulocyte subpopulations based on their fluorescence according to mRNA (low (L-R), medium (M-R) and high (H-R)), MCV ratio and MCHC ratio. Correlation between fetal haemoglobin (HbF) and RDWr in patients with thalassaemia was evaluated.

RESULTS

RDWr was significantly higher in δβ-TT compared with β-TT (15.03% vs 13.82%, p<0.001), and so were HDWr (3.65% vs 3.27%, p<0.001), CHr (23.68 vs 22.66 pg, p<0.001) and MCVr (88.3 vs 85.5 fL, p<0.001). A good correlation was observed between HbF and RDWr (r=0.551, p<0.001). IDA subjects have more immature reticulocytes, but less ARC than β-TT, suggesting a certain degree of inefficient erythropoiesis in IDA in comparison with β-TT.

CONCLUSIONS

Previously described differences between δβ-TT, β-TT and IDA in the corpuscular indices of mature red blood cell can also be observed in reticulocytes. The degree of anisocytosis in reticulocytes from patients with thalassaemia is correlated with HbF.

The risk of copper deficiency in patients prescribed zinc supplements

AIMS

In high doses zinc may cause copper deficiency, a diagnosis that is often missed resulting in anaemia, neutropenia and irreversible neurological symptoms. The aim of this study was to assess if zinc deficiency is erroneously diagnosed by misinterpretation of plasma zinc concentrations and whether copper deficiency is induced in patients prescribed zinc.

METHODS

Casenotes of 70 patients prescribed zinc were scrutinised. Plasma concentrations of zinc, copper, C reactive protein and albumin were recorded from the laboratory database.

RESULTS

62% of patients were prescribed zinc at doses sufficient to cause copper deficiency. In 48% of the patients, plasma zinc concentrations were low as a probable result of hypoalbuminaemia or the systemic inflammatory response rather than deficiency. Awareness of copper deficiency was lacking; it was only documented as a possible side effect in one patient and plasma copper was measured in only two patients prescribed zinc. 9% of patients developed unexplained anaemia and 7% developed neurological symptoms typical of copper deficiency.

CONCLUSIONS

Zinc deficiency is frequently misdiagnosed on the basis of low plasma zinc concentrations. The potential risk of copper deficiency developing in patients prescribed high doses of zinc is apparently infrequently considered. It is probable that a significant minority of patients prescribed with high doses of zinc develop iatrogenic copper deficiency.

Measurement of nucleated red blood cells in the peripheral blood as a marker of hypoxia in sudden unexpected death in infancy

AIMS

A recently proposed classification of sudden unexpected infant death incorporates consideration of possibly asphyxia. This depends on an adequate postmortem, scene investigation and history. A reliable marker of asphyxia has yet to be identified. Such a marker could assist in classifying these deaths. Our aim was to determine if the level of nucleated red blood cells (nRBCs) in the peripheral blood could help identify those possibly asphyxia-related deaths and if risk factors could influence this level in the peripheral blood.

METHODS

Cases of sudden unexpected deaths in infancy and sudden infant death syndrome (SIDS) which occurred over a period of 6 years (2007-2013) and were autopsied at Sheffield Children's Hospital were reviewed and categorised according to a new classification proposed by Randall et al. The cases were then correlated with the blood level of nRBCs determined at the time of post mortem examination. The study was approved by the Clinical Governance Department, number SE331.

RESULTS

139 deaths were classified into Group A (true SIDS, 67 cases), Group B (possible asphyxia related, 24 cases), Group C (non-asphyxia-related, 6 cases), Group D (no crime scene investigation, 0 cases) and Group E (identifiable cause, 42 cases). The levels were significantly increased in ex-premature babies, in infants with an underlying condition (Group C) and in deaths related to illness or trauma (Group E). There was a trend towards higher levels of nRBCs in younger age groups and in babies born to smoking mothers.

CONCLUSIONS

SIDS remains a difficult diagnosis to make despite the current medical technological advances where no marker of hypoxia has yet been identified.

Does transcutaneous electrical nerve stimulation (TENS) alleviate the pain experienced during bone marrow sampling in addition to standard techniques? A randomised, double-blinded, controlled trial

AIMS

Bone marrow aspiration and trephine (BMAT) biopsies remain important tests in haematology. However, the procedures can be moderately to severely painful despite standard methods of pain relief. To test the efficacy of transcutaneous electrical nerve stimulation (TENS) in alleviating the pain from BMAT in addition to standard analgesia using a numerical pain rating scale (NRS).

METHODS

70 patients requiring BMAT were randomised (1:1) in a double-blind, placebo-controlled trial. -35 patients received TENS impulses at a strong but comfortable amplitude (intervention group) and 35 patients received TENS impulses just above the sensory threshold (control group) (median pulse amplitude 20 and 7 mA, respectively). Patients and operators were blinded to group allocation. Pain assessments were made using a numerical pain scale completed after the procedure.

RESULTS

No significant difference in NRS pain recalled after the procedure was detected (median pain score 5.7 (95% CI 4.8 to 6.6) in control vs 5.6 (95% CI 4.8 to 6.4) in the intervention group). However, 100% of patients who had previous experience of BMAT and >94% of participants overall felt they benefited from using TENS and would recommend it to others for this procedure. There were no side effects from the TENS device, and it was well tolerated.

CONCLUSIONS

TENS is a safe, non-invasive adjunct to analgesia for reducing pain during bone marrow biopsy and provides a subjective benefit to most users; however, no objective difference in pain scores was detected when using TENS in this randomised controlled study.

CLINICAL REGISTRATION NUMBER

NCT02005354.

Historical perspectives in clinical pathology: a history of glucose measurement

This is the second in the series of historical articles dealing with developments in clinical pathology. As one of the most commonly measured analytes in pathology, the assessment of glucose dates back to the time of the ancient Egyptians. It was only in the 19th century that advances in chemistry led to the identification of the sugar in urine being glucose. The following century witnessed the development of more chemical and enzymatic methods which became incorporated into the modern analysers and point-of-care instruments which are as ubiquitous as the modern day cellphones. Tracking the milestones in these developments shows the striking paradigms and the many parallels in the development of other clinical chemistry methods.

Improved detection of hereditary haemochromatosis

AIMS

There is high prevalence of hereditary haemochromatosis (HH) in North European populations, yet the diagnosis is often delayed or missed in primary care. Primary care physicians frequently request serum ferritin (SF) estimation but appear uncertain as how to investigate patients with raised SF values. Our aim was to develop a laboratory algorithm with high predictive value for the diagnosis of HH in patients from primary care with raised SF values.

METHODS

Transferrin saturation (Tsat) was measured on SF samples sent from primary care; 1657 male and 2077 female patients age ≥ 30 years with SF ≥ 200 μg/L. HFE genotyping was performed on all 878 male and 867 female patients with Tsat >30%.

RESULTS

This study identified 402 (206 men; 196 women) C282Y carriers and 132 (58 men; 74 women) C282Y homozygotes. Optimal limits for combined SF and Tsat values for HH recognition were established. The detection rate for homozygous C282Y HH for male patients with both SF ≥ 300 μg/L and Tsat >50% was 18.8% (52/272) and 16.3% (68/415) for female patients with both SF ≥ 200 μg/L and Tsat >40%.

CONCLUSIONS

The large number of SF requests received from primary care should be used as a resource to improve the diagnosis of HH in areas of high prevalence.

Clinical utility of simple non-invasive liver fibrosis indices for predicting hepatocellular carcinoma (HCC) among Egyptian patients

AIM

Serological indices for liver fibrosis have been widely used to estimate liver fibrosis, but as far as we know they have not been tested to predict hepatocellular carcinoma (HCC). Our aim is to study the clinical usefulness of some simple non-invasive fibrosis indices in the prediction of HCC among Egyptian patients.

METHODS

Ninety patients with HCC who were presented to the National Cancer Institute, Cairo University, were included in this study, together with 30 patients with cirrhosis as a benign control group and 30 apparently healthy volunteers as a normal control group. FIB4 Score, Aspartate Aminotransferase (AST) to Platelet (PLT) Ratio Index (APRI) Score, AST/PLT ratio, Age/PLT Index and AST/alanine aminotransferase indices were calculated for all patients and controls and were tested for their clinical use to predict HCC.

RESULTS

Double combination between alpha-fetoprotein and FIB4 Score when either one was abnormal showed the highest diagnostic performance between the HCC group and the cirrhosis and control groups with sensitivity and specificity of (93% and 96%), respectively, whereas the APRI Score was the best to differentiate between the cirrhosis and control groups with sensitivity and specificity of 100% each.

CONCLUSIONS

Using some simple non-costly indices can accurately predict HCC and differentiate it from cirrhosis and normal control cases among Egyptian patients, it can also differentiate cirrhosis from normal controls, so can be used as diagnostic and screening tools for both HCC and liver cirrhosis among the Egyptian population.

Comparison of Becton Dickinson Vacutainer rapid serum tube with the serum separator tube for routine chemistry and immunoassay tests

AIMS

To shorten the clotting time and resolve the delayed clotting or no clotting on specimens from patients on anticoagulant therapy, Becton Dickinson (BD) recently developed the Vacutainer rapid serum tube (RST). The aim of this study was to systematically compare the new RST tube with the widely used serum separator tube (SST) for routine chemistry and immunoassay tests on 3 common analyser platforms.

METHODS

Blood from 45 people (24 women and 21 men, age 21-77 years) was collected using the SST and RST tubes in sequence. Sera from both tubes were separated and analysed simultaneously for 54, 50, and 10 chemistry and/or immunoassay tests on the Roche Modular, Abbott Architect, and Siemens Centaur analysers, respectively.

RESULTS

The results from the RST tube were comparable with those from the SST tube on most analytes. Although the results for a few analytes showed statistically significant differences between the two tubes (p<0.05), the differences had no clinical significance for most assays. Only for parathyroid hormone on the Abbott Architect, the RST tube demonstrated clinical significant bias versus the SST tube (-15.3%, p<0.01).

CONCLUSIONS

The RST tube provides acceptable performance for routine chemistry and immunoassay tests.

Reducing inpatient heritable thrombophilia testing using a clinical decision-making tool

AIMS

To evaluate the impact of a clinical decision-making tool, designed to educate physicians regarding heritable thrombophilia (HT) testing, on the volume of testing in hospitalised patients in the tertiary care setting.

METHODS

We performed a retrospective cohort study over a 6-year period (2007-2012) at a single tertiary care centre intervention site and two regional control sites. In January 2010, the intervention site instituted a policy change whereby physicians ordering HT testing on inpatients needed to complete a pre-preprinted order (PPO) form that outlined the limitations of HT testing in the hospitalised setting. Failure to complete the PPO within 24 h resulted in test cancellation. Our main outcome measure was the volume of HT testing performed at the three study sites.

RESULTS

Introduction of the PPO resulted in a 79.4% (95% CI 71.2% to 87.6%) reduction in factor V Leiden (FVL) testing at the intervention site. This decrease was significantly greater compared with those in the two control teaching hospitals over the same time periods (33.7% and 43.6%; both p<0.001). Reductions in FVL testing postintervention were observed among all ordering specialists. Similar postintervention reductions in testing volumes were observed for antithrombin (57.4%), protein C (61.9%) and protein S (62.2%) activity assays.

CONCLUSIONS

In a large tertiary care hospital, the introduction of a clinical decision-making tool significantly reduced HT testing in inpatients across clinical specialties. The impact on patient outcome should be assessed in further studies.

Serum pepsinogen reference intervals in apparently healthy Chinese population with latex enhanced turbidimetric immunoassay

AIM

Serum pepsinogen (sPG) has been used to help in diagnosing atrophic corpus gastritis and in screening for gastric cancer non-invasively. There are as yet no reports on sPG reference intervals (RIs) with latex enhanced turbidimetric immunoassay (LIA). In this study, we established the RIs for sPG in a healthy Chinese population using LIA.

METHODS

Serum PGI and PGII levels in a healthy population (aged 17-80 years) were measured simultaneously using LIA. RIs were determined following Clinical Laboratory and Standards Institute C28-A3 guidelines using a non-parametric method.

RESULTS

95% RIs in men (ng/mL) were: ≤40 years old, 25.53-100.76 for PGI and ≤24.42 for PGII; 41-50 years old, 26.62-124.74 for PGI and ≤26.81 for PGII; and 51-80 years old, 30.40-153.25 for PGI and ≤32.62 for PGII. Corresponding RIs for women (ng/mL) were: ≤40 years old, 21.20-87.44 for PGI and ≤25.53 for PGII; and 41-80 years, 26.40-127.46 for PGI and ≤30.18 for PGII. 95% RI for PGI/PGII in both men and women at any age was ≥2.51.

CONCLUSIONS

We established the RIs for sPG using LIA in a healthy Chinese population, which can provide a reference for clinical and laboratory studies.