Table 2. Zagazig University Hospital laboratory Sigma metrics calculation.

Parameters	TEa source	TEa	Bias (%)	CV (%)	Sigma
AFP	BV desirable	21.87	4.2	5.8	3.0
ALT	BV desirable	27.48	8.7	4.6	4.1
Alb	CLIA	10.00	0.6	2.0	4.6
ALP	CLIA	30.00	2.7	5.0	5.4
BD	BV desirable	44.50	2.7	3.9	10.7
BT	BV desirable	26.94	6.4	3.3	6.2
Calcium	BV Minimal	3.82	2.3	1.9	0.7
Cholesterol	BV desirable	9.01	3.2	1.6	3.3
Creatinine	BV desirable	8.87	1.9	3.8	1.8
Glucose	CLIA	10.00	1.7	2.1	3.9
LD	CLIA	20.00	1.9	3.4	5.3
Magnesium	BV Minimal	7.21	0.5	4.1	1.6
Phosphorous	BV Minimal	15.16	1.3	4.0	3.4
Potassium	BV desirable	5.61	1.1	2.4	1.8
Total protein	CLIA	10.00	1.7	1.9	4.3
Triglycerides	BV desirable	25.99	1.4	2.3	10.7
Uric acid	BV desirable	11.97	1.0	2.4	4.6
Urea	BV desirable	15.55	0.0	4.0	3.9
GGT	BV desirable	22.11	2.3	3.2	6.2
TEa – total allowable error. CV – coefficient of variation. BV – biological variation. CLIA - Clinical Laboratory Improvement Amendments. AFP - alpha fetoprotein. ALT - alanine aminotransferase. Alb – albumin. ALP - alkaline phosphatase. BD – billirubin, direct. BT- bilirubin, total. CEA - carcinoembryonic antigen. LD - lactate dehydrogenase. GGT - gamma glutamyltransferase.