Pediatric reference intervals for general clinical chemistry components – merging of studies from Denmark and Sweden

Figures & data

Table 1. Age distribution of the healthy children and adolescents.

Years of age	Total number of children	Sweden	Denmark
0.5–0.99	39	39	0
1	58	58	0
2	53	53	0
3	50	50	0
4	50	50	0
5	42	34	8
6	96	21	75
7	110	14	96
8	145	13	132
9	204	31	173
10	232	41	191
11	196	30	166
12	193	40	153
13	104	34	70
14	128	39	89
15	109	46	63
16	60	23	37
17	119	37	82

Years of age 1 include children 1– 1.99 years of age. The total number of children was 1988 (653 from Sweden and 1335 from Denmark).

Table 2. Calculated and suggested reference limits. NORIP reference limits are shown for comparison.

Component	Unit	Gender	Age	Calculated reference limits with 90% of confidence intervals^a				Number of reference values^d		Suggested reference limits
				Low		High				Low	High
Alanine trans-aminase	U/L	FM	0.5–5	8	8–8	19	18–25	1986	292	8	19
			6–17			31	30–33		1694		31
		F	18	–						10	45
		M		–							70
Albumin	g/L	FM	0.5–6	38	37–39	46	46–47	1988	389	38	46
			7–12			47	47–48		1079		47
			13–17			49	49–50		520		49
			18	–						36	48
Alkaline phos-Phatase	U/L	FM	0.5–1	124	120–133	470	358–544^b	1567	91-1	120	470
			2–5			287	255–325		194-1		290
			6–9			366	355–392		555		370
			10–11			436	398–465		426		440
		F	12–13			389	346–544		152		390
		M				525	469–616		144		530
		F	14–15	47	42–55	271	240–314	414	137	50	270
		M				418	374–479^b		100		420
		F	16–17			124	104–149^b		99		120
		M				275	212–373^b		78		280
		FM	18	–						35	105
Aspartate trans-aminase	U/L	FM	0.5–1	25	25–26	64	55–74^b	634	94-1	25	64
			2–8			47	45–48		1884		47
			9–17	17	16–17			1344		17
		F	18	–						15	35
		M		–							45
Bilirubin	µmol/L	FM	0.5–5	2	2–2	8	7–9	1981-1	292	2	8
			6–10			18	15–20		782		18
			11–17			24	21–28		907-1		24
			18	5	–	25	–			5	25
Calcium	mmol/L	FM	0.5–0.99	2.40	–^c	2.79	–^c	39		2.40	2.80
			1–4	2.29	2.27–2.32	2.64	2.62–2.65	211		2.30	2.64
			5–12	2.24	2.21–2.26	2.59	2.58–2.60	1211	1729	2.24	2.60
			13–17	2.09	2.05–2.15			518		2.10
			18	–						2.15	2.51
Cholesterol	mmol/L	FM	0.5–17	2.7	2.7–2.7	5.5	5.5–5.7	1986		2.7	5.5
			18	2.9	–	6.1	–			2.9	6.1
Creatine kinase	U/L	FM	0.5–1	35	30–40	386	262–509^b	250	97	35	390
		F	2–4			241	224–254		528-1		240
		M				301	259–344		450		300
		F	5–10	52	49–56	241	224–254	1732	528-1	50	240
		M				301	259–344		450		300
		F	11–17			328	275–442		508		330
		M				659	534–973		399		660
		F	18	–						35	210
		M		–						50	400
Creatinine	µmol/L	FM	0.5–2	19	14–20	46	42–59	150		19	46
			3–5	24	22–25	49	42–53	142-1		24	49
			6–8	28	25–29	51	49–53	349		28	51
			9–12	33	33–34	63	61–65	821		33	63
		F	13–17	39	36–41	77	75–82	293		39	77
		M		44	39–47	92	87–98	227		44	92
		F	18	–						45	90
		M		–						60	105
Iron	µmol/L	FM	0.5–0.99	4.1	3.5–5.1	17.0	–^c	248	38	4.0	17
			1–4			28.1	25.2–35.0		210		28
			5–12	6.8	6.2–7.6	29.9	29.4–31.3	1732	1212	7.0	30
			13–17			34.9	33.0–37.5		520		35
			18	–						9.0	34
Lactate dehydro-genase	U/L	FM	0.5–12	133	129–136	317	313–326	1977	1457-1	130	320
			13–17			273	261–280		520		270
			18	–						105	205
Magnesium	mmol/L	FM	0.5–3	0.77	0.76–0.79	0.96	0.95–0.96	200	1982	0.77	0.96
			4–17	0.72	0.71–0.73			1782		0.72
			18	–						0.71	0.94
Phosphate	mmol/L	FM	0.5–2	1.50	1.40–1.55	2.08	2.01–2.18	150	200	1.50	2.08
			3	1.34	1.28–1.39			100		1.34
			4			1.80	1.78-1.84		1264		1.80
			5–12	1.10	1.08-1.13			1214		1.10
			13–17	0.86	0.80-0.90	1.72	1.69-1.77	518		0.86	1.72
		F	18	–						0.85	1.50
		M		–						0.75	1.65
Potassium	mmol/L	FM	0.5–4	3.8	3.7–3.9	5.5	5.1–5.8	250		3.8	5.5
			5–17	3.3	3.3-3.3	4.6	4.5–4.6	1736		3.3	4.6
			18	–						3.5	4.4
Sodium	mmol/L	FM	0.5–17	136	136–136	146	146–146	1952		136	146
			18	–						137	144
Transferrin	g/L	FM	0.5–4	2.21	2.05–2.28	3.47	3.38–3.61	200		2.20	3.50
		F	5–12	2.13	2.11–2.17	3.36	3.33–3.45	1738	667	2.10	3.40
		M				3.31	3.28–3.38		551		3.30
		F	13–17			3.96	3.83–4.34		293		4.00
		M				3.59	3.42–3.87		227		3.60
		FM	18	–						1.87	3.19
Triglycerides	mmol/L	FM	0.5–17	0.36	0.34–0.36	2.19	2.11–2.37	1987		0.36	2.19
			18	–						0.45	2.6
Urate	µmol/L	F	0.5–9	140	133–146	320	317–331	1087^a	1078	140	320
		M		136	125–145			672		140
		F	10–12	140	133–146	342	336–352	1087^a	646^a	140	340
		M		136	125–145	364	345–383	672	267	140	360
		F	13–17	140	133–146	342	336–352	1087^a	646^a	140	340
		M		186	157–205	462	430–480	227-1	227-1	190	460
		F	18	–						155	350
		M		–						230	480

Grey-shaded rows represent NORIP reference intervals for adults. An age group specified as 0.5–5 includes children from 0.50 to 5.99 years of age.

^a The number is the sum for several age groups sharing the same reference interval.

^b The confidence interval has been calculated with the bootstrap method because of too few results.

^c Too few reference values to calculate confidence interval.

^d “−1” means that one outlier has been removed before calculating the reference interval.

Figure 1. Creatinine concentrations (µmol/L) in individual children, separated by gender.

Figure 2. Suggested reference intervals for creatinine for male children from the Colantonio et al.’s study [6], Ceriotto et al.’s study [25] and the two original data sets [9,10], as well as the presently suggested intervals (DEN/SWE). For comparison NORIP [23] intervals for males 18–19 years of age are included.

Figure 3. Alkaline phosphatase concentrations (U/L) in individual children, separated by gender.

Figure 4. Suggested reference intervals for alkaline phosphatase for females from the CALIPER project [6] and the present data set (DEN/SWE). For comparison NORIP [23] intervals for females 18–19 years of age are included.

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