Paediatric reference values for total homocysteine, tryptophan, tyrosine and phenylalanine in blood spots

Figures & data

Figure 1. Histograms of blood spot amino acid concentrations in a sample of 104 healthy children.

Table 1. Reference values for blood spot amino acid concentrations, based on a sample of 104 healthy children.

	5th percentile	10th percentile	50th percentile	90th percentile	95th percentile
Total homocysteine (μmol/L)^a	0.3 (CI −0.5–1.1)	0.5 (CI –0.3–1.3)	2.5 (CI 1.7–3.3)	6.0 (CI 5.2–6.8)	7.5 (CI 6.7–8.3)
Tryptophan (μmol/L)	40 (CI 36.4–43.6)	42 (CI 38.4–45.6)	52 (CI 48.4–55.6)	63 (CI 59.4–66.6)	65 (CI 61.4–68.6)
Tyrosine (μmol/L)	34 (CI 28.3–39.7)	34 (CI 28.3–39.7)	52 (CI 46.3–57.7)	77 (CI 71.3–82.7)	81 (CI 75.3–86.7)
Phenylalanine (μmol/L)	41 (CI 35.6–46.4)	44 (CI 38.6–49.4)	55 (CI 49.6–60.4)	71 (CI 65.6–76.4)	80 (CI 74.6–85.4)

^a Based on blood spot concentrations of a smaller sample (N = 95). CI, 95% confidence interval.