IntroductionAnalytical quality is an essential requirement for best practice in any medical laboratory. Lack of a harmonized approach for sigma calculation is considered an obstacle in the objective comparability of analytical performance among laboratories adopting sigma metrics. It is urgently needed that all laboratory professionals interested in the analytical quality to work hard towards harmonization protocol for sigma calculation in order to properly select their analytical goals. This study aims at harmonization of Sigma metrics calculation in four accredited Egyptian laboratories.Materials and methodsThis observational cross sectional study compared the sigma levels for certain biochemical parameters in the four participating laboratories.ResultsCoefficient of variation (CV) and bias were determined for some biochemical analytes, data assayed by different automated analysers in the four different accredited laboratories. The sigma level for the four medical laboratories was calculated for each biomedical parameter with changed sigma level after total allowable error (Tea) unification among participating laboratories.ConclusionEach laboratory should select the TEa goal based on clear standardized criteria of selection without any subjective preferences as either under or over estimation of Sigma metrics will affect the patient centred care negatively if laboratories use quality control procedures wrongly based on incorrect Sigma metrics calculation with subsequent misleading medical decisions.

Background: Tuberculosis (TB), is one of the major common air born infectious bacterial diseases which remains a major worldwide health problem with global mortality. Objective: To evaluate the efficiency of serum samples compared to sputum for the early diagnosis of TB, and to evaluate the levels of superoxide dismutase (SOD), catalase (CAT), total antioxidant status (TAS) and tumor necrosis factor- (TNF-) in patients with pulmonary tuberculosis (PTB). Methods: One hundred patients with clinically suspected PTB and 25 healthy individuals were enrolled in the study. According to the bacteriological results, 78 patients were diagnosed as having PTB infection. These cases were categorized into 69 culture positive cases [sputum and serum PCR positive patients (n=42), sputum PCR positive and serum PCR negative patients (n=16) and sputum and serum PCR negative patients (n=11)] and 9 culture negative and sputum PCR positive cases with radiological lung abnormalities suggestive for PTB. For these 78 cases, erythrocyte SOD, CAT, serum TAS and TNF- were determined. Twenty two patients were culture negative and negative for both sputum and serum PCR. They had no PTB and were not involved in biochemical studies. Results: In all 78 PTB patients, erythrocyte SOD, CAT and serum TAS levels were statistically lower than controls (p<0.05), while TNF- was highly significantly increased (p=0.001). There was a significant direct linear correlation between SOD and CAT and TAS (p<0.0001, r= 0.78; p<0.0001, r= 0.88; p<0.0001, r=0.80 respectively) and a significant reverse linear correlation between TNF- and SOD, CAT and TAS level (p<0.0001, r=-0.55; p<0.0001, r=-0.51; p<0.0001, r=-0.65 respectively). Conclusion: Although the sputum culture is still the gold standard for the diagnosis of patients with PTB, sputum PCR is an efficient method that could be used as an alternative to the culture for the rapid identification of PTB cases. The lower levels of SOD, CAT and TAS may be improved by the antioxidant therapy which may help in better prognosis. Anti TNF-α therapy may help in decreasing the elevated level of TNF-α shown in all PTB patients.