Table 2.

The distribution of CK-MM concentration in relation to gender, gestational age (GA), birth weight (BW) and age at sampling subgroups.

Group		N	CK-MM Percentile values (ng/mL)
			Median	25th	75th	99th	99.7th
Gender	Male	44268	113	73.0	173	544	805.8
	Female	18285	98.7	65.9	151	469	658.3
Gestational age	Premature
	<32 W	327	28.9	16.9	50.8	196.4	263.3
	32–36 W	2197	48.5	28.4	80.4	316	687.4
	36–37 W	2183	77.4	50	119	394.3	649.8
	Term 37–42 W	57812	112	74.6	171	529	772
	Overdue ≥42 W	34	144	104.5	208.5	675.6	694.1
Birth weight	Low BW
	<1000 g	41	34.6	21.8	81.4	161.2	166
	1000–1500 g	227	30.6	16.8	56	196.4	232.7
	1500–2500 g	3924	66.5	38	111	448.8	892.3
	Normal BW 2500–4000 g	56612	112	73.9	170	526	751.3
	Macrosomia ≥4000 g	1749	98.2	66	151.5	556	804.3
Age at sampling	24–48 h	13869	159	107	234	669.3	993.4
	48–72 h	29103	108	73.4	161	476	676.4
	72–168 h	18521	85.4	57.3	126	388	581.3
	≥168 h	1060	33.1	22	49.9	210.2	376.4

The distribution of CK-MM was significantly different between males and females (Mann-Whitney U test, P < 0.001).

Differences in the CK-MM concentrations for each subgroup of gestational age were statistically significant (Kruskal-Wallis test, P < 0.001).

Differences in the CK-MM concentrations for each subgroup of birth weight were statistically significant (Kruskal-Wallis test, P < 0.001).

The differences in the CK-MM concentrations for each subgroup of age at sampling were statistically significant (Kruskal-Wallis test, P < 0.001).