Associations between serum levels of insulin-like growth factor-I and bone mineral acquisition in pubertal children: a 3-year follow-up study in Hamamatsu, Japan

Table 3 Relationships between bone mineral parameters and quartile groups of IGF-I levels

			Baseline					Follow-up					Baseline and follow-up
			Mean	SD	P for ANOVA	P for ANCOVA	P for Trend	Mean	SD	P for ANOVA	P for ANCOVA	P for Trend	P for repeated measures ANOVA	P for repeated measures ANCOVA
Boys, N = 121	TBLH BMC (g)
		IGF-I Q1	567	97	< 0.001	ns^a	ns^a	963	179	< 0.001	0.013^a	ns^a	< 0.001^a	0.044^a
		IGF-I Q2	607	88				1110	195
		IGF-I Q3	654	139				1167	259
		IGF-I Q4	746	159				1333	222
	TBLH aBMD (g/cm²)
		IGF-I Q1	0.594	0.038	0.003	ns^b	ns^b	0.692	0.059	< 0.001	0.011^b	0.007^b	< 0.001^b	0.004^b
		IGF-I Q2	0.603	0.030				0.740	0.072
		IGF-I Q3	0.607	0.038				0.739	0.072
		IGF-I Q4	0.630	0.046				0.786	0.066
	TB BMAD (g/cm³)
		IGF-I Q1	0.085	0.006	< 0.001	ns^b	ns^b	0.076	0.005	0.039	ns^b	ns^b	< 0.001^b	ns^b
		IGF-I Q2	0.083	0.006				0.077	0.004
		IGF-I Q3	0.080	0.008				0.074	0.004
		IGF-I Q4	0.077	0.008				0.075	0.004
Girls, N = 133	TBLH BMC (g)
		IGF-I Q1	562	113	< 0.001	ns^a	ns^a	918	156	< 0.001	ns^a	ns^a	< 0.001^a	ns^a
		IGF-I Q2	692	124				1042	159
		IGF-I Q3	738	144				1090	165
		IGF-I Q4	808	158				1125	176
	TBLH aBMD (g/cm²)
		IGF-I Q1	0.586	0.039	< 0.001	ns^b	ns^b	0.679	0.053	< 0.001	ns^b	ns^b	<0.001^b	ns^b
		IGF-I Q2	0.625	0.041				0.718	0.063
		IGF-I Q3	0.634	0.043				0.734	0.056
		IGF-I Q4	0.653	0.050				0.749	0.057
	TB BMAD (g/cm³)
		IGF-I Q1	0.083	0.006	< 0.001	ns^b	ns^b	0.077	0.005	ns^b	0.036^b	0.006^b	ns^b	ns^b
		IGF-I Q2	0.080	0.005				0.078	0.004
		IGF-I Q3	0.078	0.006				0.078	0.006
		IGF-I Q4	0.077	0.005				0.079	0.004

IGF-I insulin-like growth factor-I; TBLH total body less head, BMC bone mineral content, N number, Q quartile, ns not significant, aBMD areal bone mineral density, TB total body, BMAD bone mineral apparent density as an estimate of volumetric bone mineral density, IGF-I Q1 the lowest quartile group of IGF-I levels, IGF-I Q4 the highest quartile group of IGF-I levels
ANOVA and ANCOVA were performed to explore differences among quartiles
Multiple linear regression analysis was performed for trend tests from lowest to highest quartiles of IGF-I levels
Repeated measures ANOVA and ANCOVA were performed to explore differences among quartiles. P < 0.05 was considered statistically significant
^aAdjusted for 25-hydroxyvitamin D, sedentary behavior, pubic hair appearance, weight, and height at baseline
^bAdjusted for 25-hydroxyvitamin D, sedentary behavior, pubic hair appearance, and weight at baseline

ISSN: 1880-6805