Table 1.

GAA enzyme activity intra- and interday assays using DBS from low to high quality controls (QCs)

	Intraday assays (n = 5)
	QC1	QC2	QC3	QC4
Mean (μmol/h/L)	0.28	0.84	6.79	13.67
Range (μmol/h/L)	0.20–0.49	0.75–0.89	6.20–7.64	11.50–15.83
RSD%	41.42	6.44	8.70	12.79
	Interday assays (n = 5)
	QC1	QC2	QC3	QC4
Mean (μmol/h/L)	0.33	1.00	7.29	13.70
Range (μmol/h/L)	(0.17–0.53)	(0.69–1.44)	(6.85–7.69)	(12.08–15.09)
RSD%	38.75	27.17	4.22	9.37

RSD relative standard deviation