Table 3 Comparison of participants’ characteristics and biochemical studies in mainly breastfed infants between vitamin D insufficiency (VDI) and vitamin D sufficiency (VDS), data are shown in mean ± SD or n (%) as appropriate

Infants

 25OHD (ng/mL)

13.7 ± 5.8

25.3 ± 7.3

< 0.01

 Parathyroid hormone (pg/mL)

31.2 ± 20.1

25.0 ± 10.6

0.09

 Calcium (mg/dL)

10.3 ± 0.34

10.4 ± 0. 3

0.45

 Phosphate (mg/dL)

5.3 ± 0.4

5.4 ± 0.3

0.49

 Albumin (g/dL)

4.5 ± 0.2

4.5 ± 0.2

0.40

 Alkaline phosphatase (IU/L)

262 ± 89

250 ± 136

0.84

Mothers

 25OHD (ng/mL)

19.0 ± 6.8

24.3 ± 6.0

< 0.01

 Parathyroid hormone (pg/mL)

38.1 ± 17.8

37.0 ± 17.1

0.89

 Calcium (mg/dL)

9.4 ± 0.4

9.4 ± 0.3

0.77

 Phosphate (mg/dL)

3.6 ± 0.5

3.8 ± 0.7

0.40

 Albumin (g/dL)

4.5 ± 0.2

4.4 ± 0.2

0.40

 Alkaline phosphatase (IU/L)

94 ± 31

100 ± 34

0.31

Characteristic

 Gender, male, n (%)

21 (62)

20 (74)

0.41

 Weight (kg)

7.7 ± 1.1

7.9 ± 1.2

0.50

 Length (cm)

67.5 ± 3.2

68.8 ± 3.3

0.10

 Head circumference (cm)

43.0 ± 1.6

43.1 ± 1.5

0.83

 Weight z-score

0.32 ± 1.23

0.36 ± 1.3

0.91

 Length z-score

0.36 ± 0.97

0.61 ± 0.91

0.31

 Head circumference z-score

-0.20 ± 1.04

-0.33 ± 0.9

0.61

 Duration of sunlight exposure per day (minutes)

11 ± 7

18 ± 10

< 0.01

 Duration of sunlight exposure per weeks (minutes)

54 ± 22

114 ± 48

< 0.01

 Time of exposure, n (%)

0.60

  Before 10.00 h

21 (62)

20 (74)

  During 10.00–15.00 h

2 (6)

1 (4)

  After 15.00 h

11 (32)

6 (22)

 Dress type, short-sleeved shirts and short pants, n (%)

29 (85)

24 (89)

0.97

 Caregivers, parents

29 (85)

22 (82)

0.74

 Family income (Baht per month)

40,000 ± 23,000

36,400 ± 25,000

0.23

 Maternal education, bachelor, n (%)

30 (88)

19 (70)

0.11