Standardization in laboratory medicine: Adoption of common reference intervals to the Croatian population

Table 1 Reference intervals for creatinine concentrations[31]

Age (gender) group	Percentile value,μmol/L
	2.5th	97.5th
Common reference intervals for global application
Cord sera	46	86
Term neonates 0-14 d	27	81
2 mo - < 1 yr	14	34
1 yr - < 3 yr	15	31
3 yr - < 5 yr	23	37
5 yr - < 7 yr	25	42
7 yr - < 9 yr	30	48
9 yr - < 11 yr	28	57
11 yr - < 13 yr	37	63
13 yr - < 15 yr	40	72
Adult (males)	64	104
Adult (females)	49	90
Reference intervals in the reference sample group of Croatian population (n = 240)
Adult (males)	54	107
Adult (females)	50	93

Table 2 Verification of reference intervals for alanine amino-transferase for Croatian patients

Analyte	Method	Unit	Reference interval			Ref.	Verification (%)
			Sex	Age (yr)	Interval
ALT	Photometry UV, IFCC method, 37 °C, TRIS buffer, L-alanine, α-ketoglutarate, pyridoxal phosphate, NADH, lactate dehydrogenase, pH 7.15: CCMB recommendation for the Croatian population	U/L	Male, female	0-2	11-46	[40]
			Male, female	3-7	9-20	[40]
			Male, female	8-12	11-37	[10,15]
			Male	13-19	10-33	[10,15]
			Female	13-19	10-29	[10,15]
			Male	≥ 20	12-48	[14]
			Female	≥ 20	10-36	[14]
	IFCC reference measurement procedure (IFCC RMS), IFCC IRMM reference material ERM-AD454 (2002): Common multicentric reference intervals for the adult population, 2010	U/L	Male	18-85	9-59	[41]	96
			Female	18-85	8-41		96
	Pediatric reference intervals
	CALIPER, Canada, 2012; IFCC reference measurement procedure, Abbott Architect		Male, female	0 < 1	5-51	[42]
			Male, female	1 < 13	11-30		90
			Male	13 < 19	10-33		55
			Female	13 < 19	8-24		65
	Denmark (NORIP), 2012; IFCC reference measurement procedure, Roche Modular		Male	5-8	8-27	[43]
			Male	9-13	8-37
			Male	14-18	8-47
			Female	5-18	8-32
	Germany (a posteriori, ambulance and hospital populations) 2009; IFCC reference measurement procedure, Roche Modular		Male, female	0-1	< 49	[44]
			Male, female	1-3	< 29
			Male, female	4-6	< 39
			Male, female	7-12	< 44
			Male	13-17	< 51
			Female	13-17	< 45

ALT: Alanine amino-transferase; IFCC: International Federation of Clinical Chemistry and Laboratory Medicine; CCMB: Croatian Chamber of Medical Biochemists; IRMM: Institute for reference materials and measurements; RMS: Reference measurement system; CALIPER: Canadian laboratory initiative on pediatric reference intervals.

Table 3 Verification of reference intervals for aspartate amino-transferase for Croatian patients

Analyte	Method	Unit	Reference interval			Ref.	Verification (%)
			Sex	Age (yr)	Interval
AST	Photometry UV, IFCC method, 37 °C, TRIS buffer, L-aspartate, α-ketoglutarate, pyridoxal phosphate, NADH, malate dehydrogenase, lactate dehydrogenase, pH 7.65: CCMB recommendation for the Croatian population	U/L	Male, female	0-2	26-75	[40]
			Male, female	3-7	24-49	[40]
			Male, female	8-12	14-39	[10,15]
			Male	13-19	11-38	[10,15]
			Female	13-19	14-32	[10,15]
			Male	≥ 20	11-38	[14]
			Female	≥ 20	8-30	[14]
	IFCC reference measurement procedure (IFCC RMS), IFCC IRMM reference material ERM-AD457 (2002): Common multicentric reference intervals for the adult population, 2010	U/L	Male, female	18-85	11-34	[41]	94
	Pediatric reference intervals
	CALIPER, Canada, 2012; IFCC reference measurement procedure, Abbott Architect		Male, female	1 < 7	26-55	[42]	100
			Male, female	7 < 12	22-41		96
			Male	12 < 19	18-40		96
			Female	12 < 19	17-33		96
	Denmark (NORIP), 2012; IFCC reference measurement procedure, Roche Modular		Male, female	5-18	17-46	[43]
	Germany (a posteriori, ambulance and hospital populations) 2009; IFCC reference measurement procedure, Roche Modular		Male, female	0-1	< 77	[44]
			Male, female	1-3	< 71
			Male, female	4-6	< 53
			Male, female	7-12	< 48
			Male	13-17	< 42
			Female	13-17	< 44

AST: Aspartate amino-transferase; IFCC: International Federation of Clinical Chemistry and Laboratory Medicine; CCMB: Croatian Chamber of Medical Biochemists; IRMM: Institute for reference materials and measurements; RMS: Reference measurement system; CALIPER: Canadian laboratory initiative on pediatric reference intervals.