Table 2. Comparisons about the concentration of serum ferritin based on general information that stratified by subgroups.

Variable	Number (%)	Serum ferritina (ng/ml)	P-value
Age (year)			<0.001
20–29	556 (27.81)	2.44±0.24
30–39	682 (34.12)	2.52±0.26
40–49	474 (23.71)	2.53±0.25
50–59	172 (8.60)	2.47±0.34
60–69	115 (5.75)	2.47±0.36
BMI (kg/m2)			<0.001
<25	1409 (70.49)	2.45±0.28
≥25	590 (29.51)	2.59±0.23
Smoking			0.447
yes	1021 (51.08)	2.50±0.27
no	978 (48.92)	2.49±0.27
Alcohol consumption			0.011
yes	1651 (82.59)	2.50±0.27
no	348 (17.41)	2.46±0.28

Serum ferritin^a: the data of serum ferritin was log-transformed and the results were present by Mean ± SD.