Table 1.

Age- and sex-specific reference intervals of myocardial enzyme activity in healthy population aged 1∼<18 years (n = 6322).

Analytes	Age partition	Sex partition	n	LL	UL	Confidence interval for LL	Confidence interval for UL
AST, U/L	1	M + F	263	29.1	57.2	26.2–29.7	56.4–57.2
	2∼<10	M + F	2928	20.1	40.7	19.9–20.4	40.4–41.1
	10∼<18	M	1518	15.7	33.8	15.4–16.1	33.4–34.1
		F	1613	14	27.7	13.5–14.3	27.3–28.8
LDH, U/L	1∼<4	M + F	1115	461	761	456–466	753–769
	4∼<12	M + F	2910	397	674	393–400	670–678
	12∼<18	M	1119	339	624	334–344	617–632
		F	1178	316	555	312–320	549–561
CK, U/L	1∼<18	M + F	6322	40.2	179	39.5–40.9	177.1–181
CKMB, U/L	1∼<6	M + F	1976	11.7	39.1	11.3–12.1	38.7–39.6
	6∼<14	M	1642	8.9	34.2	8.5–9.3	33.7–34.7
		F	1629	4.5	30.2	4.1–4.8	29.7–30.7
	14∼<18	M	507	2.5	26.3	2.2–2.9	25–27.6
		F	568	2.7∗	15.1	2.7∗	14.4–16.7

^∗2.7U/L is the lowest detection limit. Actual values could be lower.