Imran Siddiqui

Comparison of high performance liquid chromatography, radio immunoassay and electrochemiluminescence immunoassay for quantification of serum 25 hydroxy vitamin D

OBJECTIVE To compare the performance of radioimmunoassay (RIA) with high-performance liquid chromatography (HPLC) and electrochemiluminescence (ECLIA) for the quantification of vitamin D (25OHD). METHODS HPLC method for the determination of 25OHD in human biological samples was developed and compared in terms of accuracy and precision with a commercially available RIA assay. Performance of RIA assay with ECLIA technology for 25OHD analysis was further compared. RESULTS Median 25OHD levels with HPLC vs. RIA were 50.1nmol/L (IQ=17.7-199.4nmol/L) and 51.1nmol/L (IQ=12.5-187.2nmol/L) respectively, whereas median 25OHD concentration with RIA vs. ECLIA was 32.4nmol/L (9.98-199.7nmol/L) and 29.9nmol/L (4.9-214.6nmol/L), respectively. Comparison data for HPLC vs. RIA showed RIA=-1.13+1.01 (HPLC) (RMSE=11.2nmol/L) and for RIA vs. ECLIA revealed, ECLIA=3.21+0.9 (RIA) (RMSE9.6nmol/L). CONCLUSION Acceptable correlation was observed among HPLC and RIA and also with RIA and ECLIA in quantification of 25OHD.

Serum CA 125 is of clinical value in the staging and follow-up of patients with non-Hodgkin's lymphoma: correlation with tumor parameters and disease activity.

Correlation with Tumor Parameters and Disease Activity We read with interest the article published in Cancer earlier this year regarding the elevation of CA 125 in patients with non-Hodgkin’s lymphoma and its normalization with clinical response. Earlier a case report had also emerged about elevation of CA 125 in a patient within tuberculous peritonitis. We would like to add that we have seen and treated a patient with pulmonary tuberculosis who had a high CA 125 at presentation which normalized with successful treatment. A woman age 65 years was brought to the oncology clinic with a 4-month history of generalized body weakness, cough, and weight loss. She looked cachectic and emaciated. On examination, she appeared wasted and crepitations were heard in the left middle zone of the lung. Abdominal examination revealed wasting of abdominal muscles and an otherwise normal examination. She also brought with her a report of CA 125, which revealed a value of 256 IU/mL (normal, ,35 IU/mL). The patient’s daughter works as a technician in our chemical pathology laboratory and had earlier lost her father to squamous cell carcinoma of the lung. She had her mother’s CA 125 checked out of her own curiosity, and its elevation, was the reason for the oncology consultation. A chest X-ray revealed bilateral patchy infiltration and cavitation in left mid-lung zone. There was a minimal pleural effusion. The sputum smear showed acidfact bacilli. The patient began to receive a four—drug antituberculosis regimen consisting of isoniazid, rifampin, ethambutol, and pyrazinamide. Three months later, the patient had marked symptomatic improvement, the sputum examination had become negative, and serum CA 125 had decreased to 56.8 IU/mL. After 9 months of treatment for pulmonary tuberculosis, the CA 125 is 16.8 IU/mL. The chest X-ray still shows cavitation along with fibrosis; however, the sputum is negative for acid-fact bacilli. To our knowledge, this is the first report of elevation of CA 125 in a patient with pulmonary tuberculosis and its normalization with treatment. It has been suggested that CA 125 is produced by mesothelial cells, and in this case it may have represented some kind of response of pleural mesothelial cells to tuberculosis. The role of CA 125 may need to be explored further for it to be used as a routine marker for monitoring response of pulmonary tuberculosis to treatment.

B-type natriuretic peptide versus amino terminal pro-B type natriuretic peptide: selecting the optimal heart failure marker in patients with impaired kidney function

BackgroundThe effect of impaired kidney function on B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) is vague. This study was performed to examine the effect of kidney dysfunction on the afore-mentioned markers and determine appropriate cutoffs for systolic heart failure (SHF).MethodsIn this cross sectional study adults with estimated glomerular filtration rate (eGFR) <60 ml/min for ≥3 months were identified in consulting clinics from June 2009 to March 2010. SHF was defined as documented by a cardiologist with ejection fraction of < 40% and assessed by New York Heart Association classification (NYHA). Plasma was assayed for creatinine (Cr), BNP and NT-proBNP.ResultsA total of 190 subjects were enrolled in the study, 95 with and 95 without SHF. The mean age of patients was 58 (±15) years, 67.4% being males. Mean BNP levels showed a 2.5 fold and 1.5 fold increase from chronic kidney disease (CKD) stage 3 to stage 5 in patients with and without SHF respectively. NT-proBNP levels in non-heart failure group were 3 fold higher in CKD stage 5 compared to stage 3. Mean NT-proBNP levels were 4 fold higher in CKD stage 5 compared to stage 3 in patients with SHF. Optimal BNP and NT-proBNP cutoffs of SHF diagnosis for the entire CKD group were 300 pg/ml and 4502 pg/ml respectively.ConclusionBNP and NT-proBNP were elevated in kidney dysfunction even in the absence of SHF; however the magnitude of increase in NT-proBNP was greater than that of BNP. BNP and NT-proBNP can be useful in diagnosing SHF, nonetheless, by using higher cutoffs stratified according to kidney dysfunction. NT-proBNP appears to predict heart failure better than BNP.

Error identification in a high-volume clinical chemistry laboratory: Five-year experience

Abstract Introduction. Quality indicators for assessing the performance of a laboratory require a systematic and continuous approach in collecting and analyzing data. The aim of this study was to determine the frequency of errors utilizing the quality indicators in a clinical chemistry laboratory and to convert errors to the Sigma scale. Materials and methods. Five-year quality indicator data of a clinical chemistry laboratory was evaluated to describe the frequency of errors. An ‘error’ was defined as a defect during the entire testing process from the time requisition was raised and phlebotomy was done until the result dispatch. An indicator with a Sigma value of 4 was considered good but a process for which the Sigma value was 5 (i.e. 99.977% error-free) was considered well controlled. Results. In the five-year period, a total of 6,792,020 specimens were received in the laboratory. Among a total of 17,631,834 analyses, 15.5% were from within hospital. Total error rate was 0.45% and of all the quality indicators used in this study the average Sigma level was 5.2. Three indicators – visible hemolysis, failure of proficiency testing and delay in stat tests – were below 5 on the Sigma scale and highlight the need to rigorously monitor these processes. Conclusions. Using Six Sigma metrics quality in a clinical laboratory can be monitored more effectively and it can set benchmarks for improving efficiency.

Prospective evaluation of serum procalcitonin in critically ill patients with suspected sepsis- experience from a tertiary care hospital in Pakistan

Background Sepsis is the leading cause of mortality in critically ill patients. Procalcitonin (PCT) is a promising marker for identification of bacterial sepsis. The aim of this study was to determine the diagnostic accuracy of serum PCT concentration in patients with suspected sepsis admitted to mixed medical-surgical Intensive care unit (ICU). Material and methods A cross-sectional study conducted at section of Chemical Pathology, Department of Pathology and Laboratory Medicine and ICU. Patients with suspected sepsis were included, serum PCT cut off ≥0.5 ng/ml was taken for diagnosing sepsis. Diagnostic accuracy was measured in terms of sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) taking blood culture as gold standard. Furthermore, different cut offs were compared by using receiver operating characteristic curves (ROC). Data analysis was done on SPSS version 20. Results Median age of the study group (n = 103) was 48 years (IQR: 22), 60% being males. Out of the 103 patients included 82 patients had PCT levels above the optimal cut off. At a serum PCT cutoff of 0.5 μg/L, the sensitivity and specificity for the diagnosis of sepsis was found to be 93.75% and 43.59% respectively. NPV was higher compared to PPV making PCT a reliable marker to for the screening out of sepsis patients. Furthermore, it was revealed that PCT having an AUC = 0.70 outperformed WBC (AUC = 0.5) and CRP (AUC = 0.6). Conclusion Elevated PCT concentration is a promising indicator of sepsis in newly admitted critically ill patients capable of complementing clinical signs and routine laboratory parameters.

Fibroblast growth factor 23 (FGF23) levels, phosphate Intake and its association with Indices of renal handling of phosphate in healthy volunteers

FGF23 is a novel phosphaturic hormone; we aimed to assess the FGF23 levels and its association with dietary phosphate intake and indices of renal handling of phosphate in this study. Prospective study was conducted in which dietary phosphate intake was assessed by food frequency questionnaire (FFQ) along with blood and spot urine samples were collected after overnight fast for determining serum phosphate, FGF23, fractional excretion of phosphate (FePO4) and tubular maximum for phosphate (TmP/GFR). FGF23 (C-Term) was measured by a sandwich ELISA. The mean dietary phosphate intake of eighty healthy adults (mean age of 29 ± 5 years) was 1220 ± 426 mg; median FGF23 was 49.9 RU/ml (IQR=33, 76) and mean FePO4 was 7 ± 4.7. Subjects were stratified into two groups according to serum phosphate levels. Significant difference was not found in dietary phosphate intake and FGF23 levels in the two groups. However, TmP/GFR and creatinine were significantly different in the two groups. FePO4 was high in both the groups. Overall a rising pattern of FGF23 levels was seen with increasing serum phosphate levels. Significant positive correlation was found between FGF23 and dietary phosphate (r=0.22, p<0.05) and negative correlation was seen between FGF23 and FePO4 (r=-0.260, p<0.05).

Induction process of trainees in pathology residency.

This article describes the evolution of the induction process of pathology residency at The Aga Khan University hospital. The Department of Postgraduate Medical Education was established in 1985. The induction process is an exhaustive exercise that includes an admission test held simultaneously in Karachi, Hyderabad, Lahore, and Rawalpindi, followed by an interview of the shortlisted candidates. The pathology residency program was started 25 years ago and since then the induction process has undergone major changes with the course of time.

Automated Reporting of Estimated Glomerular Filtration Rate: A Comparison of Creatinine Clearance, Modification of Diet in Renal Disease and Cockcroft Gault Equations from Pakistan

Objectives: To facilitate early detection of chronic kidney disease, many organizations now recommend reflex reporting of estimated glomerular filtration rate (eGFR) whenever serum creatinine (Cr) is measured. To compare two widespread eGFR equations with creatinine clearance (CrCl) calculated through a timed urine collection. Methodology: Laboratory data of subjects’ ≥ 18 years tested for CrCl from October 2010 to December 2010 was retrieved from laboratory information system of Aga Khan University Hospital. Statistical comparison of eGFR using Cockcroft Gault (CG) and 4variable Modification of Diet in Renal Disease (MDRD) formulae with CrCl was performed. Results: Six hundred and seventy subjects with CrCl were studied. Mean age of the group was 51 ±15 years, 55.7 % being males. Mean glomerular filtration rate using CrCl, MDRD and CG were 57.1 (±35.9), 57.8 (±33.6) and 68.7 (±41.5) ml/min respectively. Deming regression analysis generated MDRD = 5.23 + 0.92 (CrCl) and CG = 0.23 + 1.2 (CrCl) for comparison of CrCl results with those of MDRD and CG respectively. Comparing MDRD and CrCl, Bland Altman revealed acceptable agreement with a minimal bias of 0.65 ml/min.