Table 1.

Statistical findings of BLL and P5N-related variables for patients and controls analyzed by unpaired t-test

Variable	Study subjects	Mean	Range		SD	Mean difference	t	P

			Min.	Max.
BLL (μg/dL)	Patients	35.89	26	48.4	6.41	27.32	23.16	<0.001
BLL (μg/dL)	Controls	8.57	3.2	15.7	3.42
P5N enzymatic activity (μmol uridine/h)	Patients	3.8	1.7	5.0	1.0	7.2	18.7	<0.001
P5N enzymatic activity (μmol uridine/h)	Controls	10.8	7.0	14.0	2.1
P5N protein amount	Patients	25.4	16.0	45.0	7.0	14.9	11.7	<0.001
P5N protein amount	Controls	10.4	6.0	17.0	2.7
Purine/pyrimidine ratio in red cells	Patients	14.3	13.0	15.3	0.6	2.7	9.2	<0.001
Purine/pyrimidine ratio in red cells	Controls	17.0	15.0	20.0	1.6

BLL: blood lead level; P5N: pyrimidine 5′-nucleotidase; SD: standard deviation, t: the size of the difference relative to the variation of samples