Age-Related Reference Intervals for Blood Amino Acids in Thai Pediatric Population Measured by Liquid Chromatography Tandem Mass Spectrometry

Table 3

Distribution of amino acid concentrations by age groups, displayed as median, 2.5th, and 97.5th percentiles.

Amino acid (µmol/L)	<4 days			6–12 months			1–3 years			3–6 years			6–12 years
	Median	P 2.5	P 97.5	Median	P 2.5	P 97.5	Median	P 2.5	P 97.5	Median	P 2.5	P 97.5	Median	P 2.5	P 97.5
Glycine	345	300	414	179.9	146.3	251.6	205.5	168.2	332.2	181.6	157.1	229	276.9	257.1	305.9
Proline	122	97	150	124	101.2	155.1	132	107	183.4	104.5	88.9	143.7	124.3	111.6	155.1
Ornithine	151	124	185	88.5	69.3	122.5	95.3	70.2	137.1	98.7	82.4	111.3	80.9	68.7	88.4
Citrulline	16.9	13.8	23	20	18.5	25.6	27	21.9	31.8	26	22.1	31.8	27	24.4	28.8
Arginine	8.4	5.6	14.7	17.2	14.2	23.5	17.4	12.7	25.1	18.4	13.8	25.8	17.2	15.4	20.7
Alanine	543	424	633	290.3	253.5	355.8	316	258.1	406.2	332.2	293	386.9	256.9	221.6	307.8
Valine	112	89.1	179.2	136	118	160.3	154	120.1	205.3	117	103	174.4	150	128.4	171.4
Leucine/isoleucine	602	511	703	376	305.4	440.1	355	282.9	436.2	319	275.3	396.1	397	343	472.5
Methionine	14.1	10.7	17.7	14.6	9.4	21.9	11.1	7	18.5	11.5	8.2	15.6	19.8	17.1	22.6
Phenylalanine	59	50.3	70.1	50.5	40.5	62.7	63.2	49.3	72.3	53.9	47.1	84.2	59.2	53.3	66.2
Tyrosine	91.1	74.1	114.4	73.5	52.6	85.5	78	58.3	93.3	61.1	50.1	91.3	72.1	62.3	84.3
Aspartic acid	205.6	102	216	125.7	94	157.4	124	87.9	212.4	104.5	85.7	137.8	120.5	88.1	148.8
Glutamic acid	592	485	687.4	237	194	306	246	201.2	283.8	239	214.8	262.3	232	211	258.7

The age-specific reference intervals were represented by the 2.5th and 97.5th percentiles according to the CLSI EP28-A3c guideline [31].