CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 5, September/October 2011
AFRICA
251
Correlations between iron indices and anthropometric indica-
tors for both men and women are displayed in Table 2. In men,
the strongest correlations were found between ferritin concentra-
tions and WC (
rs
=
0.359,
p
<
0.01) and ferritin concentrations
and WHR
(rs
=
0.396,
p
<
0.01). Likewise in women, the strong-
est correlations were found between ferritin concentrations and
WC (
rs
=
0.232,
p
<
0.01) and ferritin concentrations and WHR
(
rs
=
0.319,
p
<
0.01).
Iron indices are compared according to WHR and gender
categories in Table 3. In men, mean (geometric) serum ferritin
concentrations were significantly higher in the high-WHR group
than the normal-WHR group (
p
<
0.0001), although this disap-
peared after adjusting for age, BMI and smoking. In addition,
mean (geometric) serum iron concentration was also significant-
ly higher in the high-WHR group than the normal-WHR group
(
p
=
0.020) after adjusting for age, BMI and smoking.
In women, mean (geometric) serum ferritin and haemoglobin
concentrations were significantly higher in the high-WHR group
than the normal-WHR group before (
p
<
0.0001,
p
=
0.003,
respectively) and after (0.004,
p
=
0.018, respectively) adjusting
for age, BMI and smoking. Women in the normal-WHR group
had higher mean (geometric) serum TIBC than those in the high-
WHR group before (
p
<
0.0001) and after (
p
=
0.019) adjusting
for age, BMI and smoking. No significant differences were
observed for serum iron concentration and transferrin saturation
between the two WHR categories before and after adjusting for
age, BMI and smoking.
The comparison of anthropometric indices according to
TABLE 1. ANTHROPOMETRICAND HAEMATOLOGICAL CHARACTERISTICS OF PARTICIPANTS
Men (n
=
711, 42.80%)
Optimum
cut-off point
Women (n
=
952, 57.20%)
Optimum
cut-off point
Variable
G-Mean (SE)
Min, max
G-Mean (SE)
Min, max
Age (years)
34.32 (0.58)
15.00, 82.00
–
35.04 (0.46)
15.00, 90.00
–
Serum Fe (
µ
mol/l)
16.52 (0.33)
0.74, 73.42
≥
11
22
13.13*
#
(0.24)
0.26, 59.85
≥
11
22
Serum TIBC (
µ
mol/l)
63.86 (0.49)
28.77, 197.22
≤
73
22
68.21*
#
(0.44)
29.13, 171.12
≤
73
22
Transferrin saturation (%)
25.86 (0.53)
1.34, 102.22
20–50
21
19.18*
#
(0.39)
0.35, 97.03
20–50
21
Serum ferritin (
µ
g/l)
104.12 (12.04)
1.00, 2877.17
12–150
21
39.40*
#
(5.10)
0.28, 2678.53
12–150
21
Hb (g/dl)
13.30 (0.79)
4.70, 22.90
13–18
21
12.00*
#
(0.67)
4.70, 31.10
12–16
21
BMI (kg/m
2
)
20.80 (0.15)
13.76, 65.39
18.5–24.9
20
26.13* (0.21)
14.60, 53.64
18.5–24.9
20
WC (cm)
73.95 (0.35)
53.60, 126.20
≤
80
23
77.25*
#
(0.42)
46.50, 130.20
≤
80
23
WHR
0.84 (0.00)
0.59, 1.52
≤
0.95
20
0.76*
#
(0.00)
0.47, 1.00
≤
0.80
20
Body fat (%)
20.63 (0.26)
9.17, 39.30
47.06*
#
(0.45)
13.30, 83.79
TSF (mm)
7.36 (0.19)
1.80, 37.30
18.89*
#
(0.33)
3.50, 52.10
SSF (mm)
9.63 (0.22)
3.00, 40.00
18.69*
#
(0.42)
4.40, 60.00
*Significant difference between men and women before adjusting for age, BMI and smoking (
p
<
0.05).
#
Significant difference between men and women after adjusting for age, BMI and smoking (
p
<
0.05). BMI: body mass index, G-Mean: geomet-
ric mean, Hb: haemoglobin, SE: standard error, TIBC: total iron binding capacity, TSF: triceps skinfold, SSF: subscapular skinfold, WC: waist
circumference, WHR: waist-to-hip ratio.
TABLE 2. CORRELATIONS OF IRONANDANTHROPOMETRIC INDICES OF PARTICIPANTS
Anthropometric
indices
Iron Indices
Serum Fe (
µ
mol/l)
TIBC (
µ
mol/l)
Transferrin saturation (%)
Ferritin (
µ
g/l)
Hb (g/dl)
(r
s
)
(r
p
)
(r
s
)
(r
p
)
(r
s
)
(r
p
)
(r
s
)
(r
p
)
(r
s
)
(r
p
)
Men
BMI (kg/m
2
)
0.015
–
119**
–
–0.032
–
0.141**
–
–0.056
–
WC (cm)
0.010 –0.043
0.000
0.004
0.006
–0.049 0.359**
0.068 –0.047 –0.064
WHR
0.027
0.067 –0.157** –0.004
0.079*
0.062
396**
0.014
0.003
0.016
Body fat (%)
–0.048 –0.009 –0.029
0.008
–0.
0.012 0.308**
0.102 –0.111* –0.096
TSF (mm)
0.012 –0.044
0.097* 0.051
0.071
–0.052 0.076*
–0.028 –0.022 –0.056
SSF (mm)
0.019 –0.031
0.035
0.001
–0.005
–0.027 0.141**
0.010 –0.018 –0.059
Women
BMI (kg/m
2
)
–0.039
–
–0.041
–
–0.021
–
0.126**
–
–0.065*
–
WC (cm)
–0.036 –0.007 –0.087** –0.045
–0.008
0.014 0.232**
0.024 –0.008
0.089
WHR
–0.044 –0.016 –0.166** –0.026
0.004
0.008 0.319**
0.031
0.083* 0.126
Body fat (%)
–0.013 –0.021 –0.023
0.082
–0.002
–0.054 0.126**
0.012 –0.063 –0.011
TSF (mm)
–0.062 –0.053 –0.025 –0.012
–0.048
–0.047 0.040
–0.059 –0.037 –0.015
SSF (mm)
–0.029 –0.035 –0.040 –0.008
–0.014
–0.027 0.105** –0.038
0.072* –0.025
**Spearman correlation coefficient is significant at the 0.01 level (2-tailed).
*Spearman correlation coefficient is significant at the 0.05 level (2-tailed).
r
s
: Spearman correlation;
r
p
: partial correlation after adjusting for age,
BMI and smoking. BMI: body mass index, Hb: haemoglobin, SD: standard deviation, TIBC: total iron-binding capacity, TSF: triceps skinfold,
SSF:, subscapular skinfold, WC: waist circumference, WHR: waist-to-hip ratio.
