Raised serum uric acid is associated with higher bone mineral density in a cross-sectional study of a healthy Indian population

Figures & data

Table 1 Baseline characteristics and laboratory parameters of the study population stratified by uric acid status

	All subjects (N=310)	Low uric acid group (n=156)	High uric acid group (n=154)	p-value
Demographic characteristics
Age (years)	47.2±12.2	48.0±12.3	46.4±12.1	0.261
Height (m)	1.7±0.1	1.6±0.1	1.7±0.1	<0.001*
Weight (kg)	73.9±13.5	68.1±11.3	79.7±13.0	<0.001*
BMI (kg/m^2)	26.7±3.9	25.7±3.4	27.7±4.1	<0.001*
Female (%)	43.5	33.9	9.7	<0.001*
Male (%)	56.5	16.5	40.0
Lifestyle characteristicsa
Nonsmoker (%)	85.4	45.5	39.9	0.014*
Smoker (%)	14.6	4.9	9.7
No alcohol consumption (%)	71.4	40.6	30.8	0.001*
Alcohol consumption present (%)	28.6	9.7	18.8
No exercise (%)	5.5	2.9	2.6	0.824
Exercise present (%)	94.5	47.4	47.1
Vegetarian diet (%)	39.1	20.4	18.8	0.557
Nonvegetarian diet (%)	60.9	29.6	31.2
Laboratory parameters
Alkaline phosphatase (mg/dL)	68.2±21.0	67.3±22.7	69.1±19.1	0.470
Calcium (mg/dL)	9.3±0.4	9.2±0.3	9.3±0.4	0.017*
Phosphorus (mg/dL)	3.5±0.5	3.5±0.5	3.5±0.5	0.503
Glucose (fasting) (mg/dL)	101.5±25.5	101.6±28.4	101.3±22.4	0.910
Glycosylated hemoglobin (%)	5.6±0.8	5.6±0.9	5.7±0.7	0.788
Total cholesterol (mg/dL)	183.6±38.3	179.7±39.0	187.6±37.3	0.071
HDL (mg/dL)	42.3±9.7	45.6±10.7	39.0±7.2	<0.001*
LDL (mg/dL)	120.7±34.9	113.7±35.9	127.8±32.5	<0.001*
VLDL (mg/dL)	29.6±21.4	27.7±26.4	31.5±14.5	0.124
Triglycerides (mg/dL)	144.2±84.2	131.1±93.0	157.3±72.4	0.006*
Uric acid (mg/dL)	5.4±1.3	4.3±0.8	6.5±0.7	0.001*
25 hydroxyvitamin D (ng/dL)	21.1±16.7	19.3±12.6b	22.8±19.8c	0.285

Notes: All absolute values are presented as mean ± SD.

a Percentages for “total” are shown. Low uric acid group: uric acid ≤5.4 mg/dL; high uric acid group: uric acid >5.4 mg/dL.

b n=50,

c n=53.

* p-value <0.05.

Abbreviations: BMI, body mass index; HDL, high-density lipoprotein; LDL, low-density lipoprotein; VLDL, very low-density lipoprotein.

Table 2 Absolute BMD and T-scores stratified by uric acid status

	All subjects (N=310)	Low uric acid group (n=156)	High uric acid group (n=154)	p-value
BMD (g/cm^2)
Lumbar spine	1.129±0.157	1.097±0.152	1.161±0.156	0.001*
Left femur neck	0.959±0.145	0.926±0.133	0.992±0.150	0.001*
Right femur neck	0.960±0.136	0.926±0.127	0.995±0.137	0.001*
Left total femur	0.987±0.137	0.956±0.136	1.019±0.132	0.001*
Right total femur	0.982±0.131	0.953±0.132	1.012±0.124	0.001*
T-scores
Lumbar spine	−0.5±1.2	−0.7±1.2	−0.4±1.2	0.013*
Left femur neck	−0.7±1.0	−0.8±0.90	−0.5±1.1	0.003*
Right femur neck	−0.6±0.96	−0.8±0.80	−0.5±1.0	0.003*
Left total femur	−0.5±0.97	−0.6±1.0	−0.4±0.90	0.137
Right total femur	−0.5±0.93	−0.6±0.90	−0.4±0.80	0.188
Subjects, n (%) with T-scores ≤−2.5 (osteoporosis)a
Lumbar spine	20 (6.5)	14 (4.5)	6 (1.9)	0.069
Left femur neck	14 (4.5)	10 (3.2)	4 (1.3)	0.106
Right femur neck	9 (2.9)	6 (1.9)	3 (1.0)	0.320
Left total femur	5 (1.6)	5 (1.6)	0	0.025*
Right total femur	7 (2.3)	6 (1.9)	1 (0.3)	0.058

Notes: All absolute values are presented as mean ± SD. Percentages for “total” are shown. Low uric acid group: uric acid ≤5.4 mg/dL; high uric acid group: uric acid >5.4 mg/dL.

a Prevalence analysis done using the World Health Organization classification based on T-score: normal BMD (T-score ≥−1), osteopenia (T-score <−1 and >−2.5), and osteoporosis (T-score ≤−2.5).

* p-value <0.05.

Abbreviation: BMD, bone mineral density.

Table 3 Pearson’s correlation coefficient (r) between uric acid concentration and BMD

Model	Lumbar spine	Left femur neck	Right femur neck	Left total femur	Right total femur
1	0.211*	0.263*	0.277*	0.275*	0.273*
2	0.198*	0.250*	0.265*	0.264*	0.263*
3	0.136*	0.182*	0.194*	0.180*	0.182*
4	0.167*	0.216*	0.242*	0.237*	0.240*
5	0.179$	0.258*	0.312*	0.318*	0.321*

Notes: 1, Uncontrolled bivariate correlation; 2, age-controlled partial correlation; 3, age- and BMI-controlled partial correlation; 4, smoking-, alcohol use-, physical activity-, and diet-controlled partial correlation; 5, 25-hydroxyvitamin D-controlled partial correlation.

* p<0.05,

$ p=0.072.

Abbreviations: BMD, bone mineral density; BMI, body mass index.

Table 4 Simple linear regression between uric acid and BMD

	R	R^2	Adjusted R^2	Unstandardized coefficients	Standardized coefficients (β)	p-value
Lumbar spine	0.211	0.045	0.041	0.025	0.211	0.001*
Left femur neck	0.263	0.069	0.066	0.029	0.263	0.001*
Right femur neck	0.277	0.077	0.074	0.029	0.277	0.001*
Left total femur	0.275	0.076	0.073	0.029	0.275	0.001*
Right total femur	0.273	0.075	0.072	0.027	0.273	0.001*

Notes: Dependent variable: BMD; independent variable: uric acid.

* p<0.05.

Abbreviation: BMD, bone mineral density.

Table 5 Linear regression-r² change by uric acid in age- and BMI-adjusted model

Model	R	R^2	Adjusted R^2	SE of the estimate	R^2 change	F change	p-values for F change
Lumbar spine
1	0.347	0.120	0.114	–	–	–	–
2	0.369	0.136	0.128	0.147	0.016	5.630	0.018*
Left femur neck
1	0.414	0.171	0.166	–	–	–	–
2	0.446	0.199	0.191	0.131	0.027	10.381	0.001*
Right femur neck
1	0.401	0.161	0.155	–	–	–	–
2	0.439	0.192	0.184	0.124	0.032	11.925	0.001*
Left total femur
1	0.387	0.150	0.144	–	–	–	–
2	0.421	0.178	0.169	0.126	0.028	10.156	0.002*
Right total femur
1	0.380	0.144	0.139	–	–	–	–
2	0.416	0.173	0.164	0.120	0.028	10.315	0.001*

Notes: 1, Predictors: age and BMI; 2, predictors: age, BMI, and uric acid. Dependent variable: BMD.

* p<0.05.

Abbreviations: BMD, bone mineral density; BMI, body mass index; SE, standard error.