High prevalence of vitamin A deficiency in Crohn's disease patients according to serum retinol levels and the relative dose-response test

Table 2 Serum retinol levels and relative dose response test results with mean and standard deviation

Serum retinol categories1	CD Patients		Controls
	n (%)	Serum retinol values	n (%)	Serum retinol values
Normal levels (≥ 1.05 μmol/L)	27 (71)	2.69 ± 1.47	28 (85)	2.63 ± 1.29
Deficiency (< 1.05 μmol/L)	11 (29)	0.49 ± 0.26	5 (15)	0.74 ± 0.32
Mild deficiency (1.05-0.70 μmol/L)	2 (5)	1.00 ± 0.00	3 (9)	0.96 ± 0.05
Moderate deficiency (0.70-0.35 μmol/L)	5 (13)	0.46 ± 0.05	1 (3)	0.50 ± 0.00
Severe deficiency (< 0.35 μmol/L)	4 (11)	0.28 ± 0.02	1 (3)	0.3 ± 0.00
RDR test
Positive (≥ 20%)	14 (37)	0.97 ± 0.87	4 (12)	0.67 ± 0.33
Negative (< 20%)	24 (63)	2.68 ± 1.59	29 (88)	2.58 ± 1.30

¹WHO, 1996[29]. CD: Crohn's disease; RDR: Relative dose response.