Are sodium and potassium results on arterial blood gas analyzer equivalent to those on electrolyte analyzer?

OBJECTIVES: The present study was conducted with the aim to compare the sodium (Na) and  potassium (K) results on arterial blood gas (ABG) and electrolyte analyzers both of which use direct ion selective electrode technology. MATERIALS AND METHODS: This was a retrospective study in which data were collected for simultaneous ABG and serum electrolyte samples of a patient received in Biochemistry Laboratory during February to May 2015. The ABG samples received in heparinized syringes were processed on Radiometer ABL80 analyzer immediately. Electrolytes in serum sample were measured on ST-100 Sensa Core analyzer after centrifugation. Data were collected for 112 samples and analyzed with the help of Excel 2010 and  Statistical software for Microsoft excel XLSTAT 2015 software. RESULTS: The mean Na level in serum sample was 139.4 ± 8.2 mmol/L compared to 137.8 ± 10.5 mmol/L in ABG (P < 0.05). The mean difference between the results was 1.6 mmol/L. Mean K level in serum sample was 3.8 ± 0.9 mmol/L as compared to 3.7 ± 0.9 mmol/L in ABG sample (P < 0.05). The mean difference between the results was 0.14 mmol/L. Statistically significant difference was observed in results of two instruments in low Na (<135 mmol/L) and normal K (3.5-5.2 mmol/L) ranges. The 95% limit of agreement for Na and K on both instruments was 9.9 to -13.2 mmol/L and 0.79 to -1.07 mmol/L respectively. CONCLUSIONS: The clinicians should be cautious in using the electrolyte results of electrolyte and ABG analyzer in inter exchangeable manner.

Does LDL-C Estimation Using Anandaraja's Formula Give a Better Agreement with Direct LDL-C Estimation than the Friedewald's Formula?

Estimation of low density lipoprotein cholesterol (LDL-C) is crucial in management of coronary artery disease patients. Though a number of homogenous assays are available for estimation of LDL-C, use of calculated LDL-C by Friedewald's formula (FF) is common in Indian laboratories for logistic reasons. Recently Anandaraja and colleagues have derived a new formula for calculating LDL-C. This formula needs to be evaluated before it is extensively applied in diagnosis. We measured LDL-C by homogenous method (D-LDL-C) in 515 fasting samples. Friedewald's and Anandaraja's formulas were used for calculation of LDL-C (F-LDL-C and A-LDL-C, respectively). The mean LDL-C levels were 123.3 ± 53.2, 112.4 ± 50.2 and 109.2 ± 49.8 mg/dl for D-LDL-C, F-LDL-C and A-LDL-C, respectively. There was a statistically significant difference between the results (P > 0.001) obtained by calculation formulas compared to the measured LDL-C. There was underestimation of LDL-C by 10.8 and 14 mg/dl by Friedewald's and Anandaraja's formulas respectively. The Pearson's correlation between F-LDL-C and D-LDL-C was 0.931 and that between A-LDL-C and D-LDL-C was 0.930. Bland-Altman graphs showed a definite agreement between mean and differences of the calculation formulas and direct LDL-C with 95% of values lying with in ±2 SD limits. The mean percentage difference (calculated as {(Calculated LDL-C)-(D-LDL-C)}/D-LDL-C × 100) for F-LDL-C was maximum (-11.6%) at HDL-C ≥ 60 mg/dl and TG levels of 200-300 mg/dl (-10.4%) compared to D-LDL-C. A-LDL-C results gave highest mean percentage difference at total cholesterol concentrations <100 mg/dl (-37.3%) and HDL-C < 40 mg/dl (-17.1%), respectively. The results of our study showed that FF is better in agreement with D-LDL-C than Anandaraja's formula for estimation of LDL-C by calculation though both lead to its underestimation.

To Establish the Reference Intervals of Lipid Profile in Punjab.

Overnight fasting samples of 1,031 apparently healthy people of Punjab visiting the hospital over a period of 3 years were tested for serum lipid profile. The mean ± SD of serum total cholesterol, triglycerides, high density lipoprotein cholesterol, low density lipoprotein cholesterol and very low density lipoprotein cholesterol in mg/dl were 182.2 ± 33.9, 122.4 ± 33.4, 44.1 ± 6.8, 113.9 ± 32.0, 24.6 ± 7.1 respectively. When these subjects were grouped according to age and sex, no appreciable difference was observed between most of the groups. Serum triglycerides were found to be low and HDL-C was high in females when compared with males of similar age and vice versa. With advancing age, total cholesterol and low density lipoprotein cholesterol levels were found to be higher in women. The present study suggests that the obtained lipid values should be taken into consideration during clinical evaluation.

Paraoxonase (PON1) activity in north west Indian Punjabis with coronary artery disease & type 2 diabetes mellitus.

BACKGROUND & OBJECTIVE: Paraoxonase (PON1), an arylesterase is associated with high density lipoprotein cholesterol (HDL-C). PON1 prevents low density lipo-protein cholesterol (LDL-C) from peroxidation and can also hydrolyze lipid peroxides, thereby providing protection against atherosclerosis and coronary artery disease (CAD). The incidence of CAD is known to be high in north western Indian Punjabis. Though many factors may play a role in its pathogenesis, low PON1 activity could be an independent risk factor. We carried out this study to determine PON1 activity in north-west Indian Punjabi patients with CAD with and without type 2 diabetes mellitus and compared with healthy individuals. METHODS: A total of 120 patients with angiographically proven CAD (57 with and 63 without type II diabetes mellitus) and 19 healthy controls were studied for plasma PON1 activity and lipid variables. Comparison was undertaken between CAD patients and healthy controls and between CAD patients with and without type II DM. RESULTS: Significantly lower plasma PON1 activity (P<0.05) along with lower HDL-C (P<0.001) and higher LDL-C (P<0.05) levels were observed in CAD patients as compared to healthy controls. On univariate analysis of variance after adjusting for age and sex, no significant difference could be observed between PON1 activity and age and sex. On discriminant analysis, no clear cut-off could be observed in PON1 activity between patients CAD and controls. Similarly between CAD with and without patients type II diabetes mellitus, there was no significant difference in PON1 activity and lipids. INTERPRETATION & CONCLUSION: The low plasma PON1 activity irrespective of being diabetic may be an independent risk factor for CAD in north-western Indian Punjabi population. Similar studies involving larger samples in different ethnic groups in India need to be done to find out the role of PON1 activity in CAD.

A study to compare the plasma glucose levels obtained in sodium fluoride and citrate buffer tubes at a tertiary care hospital in Punjab.

OBJECTIVES: Recent guidelines for estimation of glucose recommend the use of citrate buffer tubes to inhibit glycolysis if the sample cannot be cooled immediately and separated within 30 min. These tubes are currently not available in India. We prepared the citrate tubes and compared the glucose results obtained with sodium fluoride tubes. METHODS: Random blood samples of 44 apparently healthy volunteers were collected in three pairs of citrate buffer and sodium fluoride tubes during September to October 2013. They were labeled as 0 h, 1 h and 2 h samples indicating a delay in centrifugation to separate plasma. Glucose was analyzed on the fully auto analyzer in duplicates using glucose oxidase-peroxidase method. RESULTS: The mean glucose concentrations at 0 h in citrate tubes were 105.8 ± 19.5 mg/dl compared to 99.6 ± 18.3 mg/dl in sodium fluoride tube. There was statistically significant difference in the glucose levels measured in plasma separated from citrate buffer tube and sodium fluoride tube at 0 h, 1 h, and 2 h. The difference between citrate and sodium fluoride tube results ranged from 6.1 mg/dl at 0 h to 7.4 mg/dl at 2 h. Glucose levels decreased significantly at 2 h in both citrate and sodium fluoride tubes. CONCLUSION: There is a significant decrease in glucose levels in sodium fluoride tubes even with immediate separation of plasma. There is urgent need to standardize the preanalytical conditions for glucose estimation so that effective inhibition of glycolysis can be done.

The attitudes and perceptions of medical students towards basic science subjects during their clinical years: A cross-sectional survey.

INTRODUCTION: In the conventional system of medical education, basic subjects are taught in the 1(st) year with least interdisciplinary interaction. The objective of this study was to explore the students' perception about content, need and application of basic science subjects during the clinical years of their medical education. MATERIALS AND METHODS: A total of 300 questionnaires were distributed among students randomly after taking their written consent for participation in the study. About 265 completely filled questionnaires were received back and the response was analyzed. RESULTS: Students identified anatomy as the subject with overloaded syllabus (75.4%) and also with maximum clinical application with 50.1% of them considering it the most important basic subject. Students were satisfied with the practical integration of subjects to impart clinical skills, but considered problem based learning a better method of teaching. According to 37%, 43.8% and 33.2% of respondents respectively; anatomy, biochemistry and physiology curriculum should only cover the general concepts to give the working knowledge of the subject. Approximately, 65% of the respondents were able to recall the knowledge of anatomy and physiology while biochemistry was retained by 40%. CONCLUSIONS: Overall, the attitudes of students toward basic science subjects were positive. The learning experience for them can be improved significantly by better clinical integration of the subjects.

Are we using Thyroid Function Tests Appropriately?

Thyroid function tests are very important for the diagnosis and monitoring of patients with thyroid dysfunction. The guidelines recommend serum thyroid stimulating hormone (TSH) as the single most reliable test to diagnose all common forms of hypothyroidism and hyperthyroidism. The aim of this study was to analyze the ordering pattern for thyroid function tests by physicians and the analysis of results based on the clinical history. The mean age of the patients was 32.5 ± 6.5 years. Majority of samples (87.7% of total) were received from the departments of Medicine and Gynae. Thyroid profiles (47.5%) were ordered more frequently as compared to TSH only (46%). There was no significant difference in the percentage of normal reports for both types of tests. 77.8% of TFT and 76.6% of TSH samples had results within the reference range. The percentage of abnormal results was 13.7% in the patients who were screened for thyroid disorders. There is a need to redefine the case definition for thyroid dysfunction and order the appropriate test in a rational and cost effective manner.