Lower reference limits of quantitative cord glucose-6-phosphate dehydrogenase estimated from healthy term neonates according to the clinical and laboratory standards institute guidelines: a cross sectional retrospective study

Table 1 Characteristics of G6PD values and lower reference limits (2.5th percentiles) in presence of outliers

	Males (n = 207)	Females (n = 188)	Combined (n = 395)
Mean (SD)^a	14.1 (2.1)	14.1 (2.1)	14.1 (2.1)
Median (interquartile range)^a	14.1 (12.9-15.3)	14.2 (13.2-15.2)	14.1 (13.0-15.3)
Mode^a	14.7	15.1	13.3
z-score of skewness^b	0.07/0.17 = 0.41	-0.93/0.18 = 5.2	-0.40/0.12 = -3.3
z-score of kurtosis^b	2.3/0.34 = 6.8	3.9/0.35 = 11.1	3.0/0.25 = 12.0
Skewness coefficient (P-value)	.66	<.001	.002
Kurtosis coefficient (P-value)	<.001	<.001	<.001
Anderson-Darling test (P-value)	<.001	<.001	<.001
Shapiro-Wilk test (P-value)	<.001	<.001	<.001
Two-stage transformation parametric	9.8 (8.8-10.7)	9.4 (7.9-10.6)	Unreliable as transformed distribution is not normal
LRL (95% CI)^a
Bootstrap LRL (95% CI)^a	10.0 (7.3-10.9)	9.0 (5.5-10.9)	10.0 (7.5-10.7)
Non-parametric LRL (95% CI)^a	10.0 (7.1-10.8)	9.0 (5.2-10.9)	10.0 (7.1-10.7)
Combination tests
1. Proportion of observations	4/207 (1.9%)	5/188 (2.7%)
less than the combined LRL
(proportion criteria)		1.0
2. Harris-Boyd method		Zero
Larger SD/Smaller SD		6.4
Normal deviate z test
Critical z value of 5

ISSN: 1471-2431