Farooq Ghani

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.

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.

Verification and Determination of the Thyroid Peroxidase Antibody Reference Interval: Insight Into the CLSI Guideline

Objective To verify the upper reference limit and define the population-based reference interval (RI) for thyroid peroxidase antibody, according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Material and Methods We subjected serum samples from 146 subjects to thyroid-stimulating hormone (TSH) and TPO Ab analysis for verification and determination of RI. We verified an upper reference limit for thyroid peroxidase antibody (TPO Ab) and established an RI according to National Academy of Clinical Biochemistry (NACB) and CLSI guidelines. Results The manufacturers suggested upper reference limit was not verified for use as a functional reference value. Rather, on defining the RI of TPO Ab by means of a full-scale study, we found a higher upper reference limit (13.8 vs 12.0). We calculated lower and upper reference limits of 3.3 and 13.8, with 90% confidence intervals (CIs) of 2.8 to 3.5 and 13.6 to 14.8, respectively. Conclusion RIs provided by assay manufacturers are general data and may not always be appropriate for different locations and patient demographics. Verification of an RI is necessary before use in a given patient population.

Epidemiology of Stone Disease in Pakistan

Urinary tract stones are a common affliction across river, desert, and mountainous regions of Pakistan. A third of the stones have a single component. The commonest stone is composed of oxalate, with phosphate and uric acid as additional components. Calcium oxalate monohydrate is more abundantly present than the dihydrate. Phosphate stones comprise only about 7 % of all stones, and struvite is uncommon. Populations in the north have a greater proportion of pure and predominantly oxalate stones. Rural areas in the south have phosphate stones. The government of British India documented the frequent occurrence of stone in this region from the nineteenth century. The commonest stone was vesical. Noted stone transitions include (1) the marked increase in the discovery of renal stones, (2) the disappearance (except in pockets) of the idiopathic adult vesical stone, and (3) the decrease in children in the proportions of stones that are vesical. Late presentation for treatment and consequent renal destruction are still frequent.

Environmental and food Allergens reactivity and its association with total IgE, age and gender in Karachi, Pakistan

Aim: The aim of this study is to assess the frequency of food and environmental allergens reactivity and its association in with age, gender and total IgE levels Material and methods: The study population consisted of 88 individuals including children and adults (male: 47 and female: 41). The study was conducted in the clinical laboratory, Department of Pathology and Laboratory Medicine, Aga Khan University Hospital from May 2009 till May 2010. Sera of patients positive for total IgE were tested for allergen specific IgE levels by Immulite 2000, 3gAllergyTM. We divided allergens into two panels, namely food and environmental. Results: There were a total of 27 allergens tested on 88 individuals who had elevated levels of total IgE. Median age was 18 yrs. (IQR 8-36). We have analyzed the data on two cutoffs of allergen specific IgE reactivity i.e. moderate (0.7-3.49 kU/L) and high (3.5-17.49 kU/L). In the environmental allergens group the moderate rates of reactivity were to dog epithelium (46.6%), mites (33%) and cockroach. (17%). From food panel moderate reactivity were to egg white (23.9%), milk (22.7%) and soybean (13.6%). High reactivity rates were seen to mites (6.8%), cockroach (4.5%), cat dander epithelium (3.4%), D.farinae (3.4%), molds (3.4%) and weeds (3.4%). Commonest food allergens with high reactivity were egg white (2.3%), peanuts (2.3%) and shrimps (2.3%). Very high reactivity of environmental allergens (>52.50 kU/L) were mites (2.3%), cat dander epithelium (1.1%) whereas in food panel it was shrimps (1.1%) and peanuts (1.1%). Positive significant association of food allergens reactivity is seen with gender (p=0.01), age (p ≤ 0.001) and total IgE (p=0.05). On the other hand positive significant association of environmental allergens reactivity is seen with age (p=0.02) and total IgE (p ≤ 0.001). Conclusion: Mites, cat dander, dog epithelium and cockroach were the most frequent environmental allergens and egg white, peanuts and shrimps were the most prevalent food allergens. There was a positive correlation between age, gender, total IgE levels and IgE specific allergens. Our study demonstrates high rates of reactivity to major environmental and food allergens in patients with high total IgE.