Table 1.

Age-adjusted (standardized to the 2000 USA census age distribution) weighted characteristics by levels of serum normalised calcium, NHANES III 1988–1991.

	Serum normalized total calcium (mmol/l)
Lowest 5%, <1.16	Mid 90%, 1.16–1.31	Top 5%, ≥1.31
n	182	4852	324
Age (years)
Mean (s.e.m.)	47.52 (0.63)	45.91 (0.14)	46.13 (0.56)
Sex (%)
Men	38.65	47.33	39.88
Women	61.25	52.67	60.12
Race – ethnicity (%)
Non-Hispanic white	84.66	76.98	74.30
Non-Hispanic black	8.18	10.26	13.75
Mexican American	5.21	4.99	3.41
Other	1.94	7.76	8.54
Waist circumference (cm)
Mean (s.e.m.)	92.75 (1.50)	92.49 (0.38)	91.21 (1.06)
BMI (kg/m2)
Mean (s.e.m.)	26.7 (0.66)	26.77 (0.17)	26.32 (0.41)
Cigarette smoking (%)
Never	41.52	46.91	40.55
Former	30.21	25.88	34.05
Current	28.26	27.21	25.40
Alcohol intake (%)
Up to once a week	67.48	63.96	66.89
Two to three times a week	9.72	15.13	11.90
Four to six times a week	11.36	11.21	9.85
Daily or more	6.61	9.70	11.36
Vigorous physical activity (%)	11.92	9.89	11.49
Diabetes (%)	6.24	3.78	5.88
Calcium (mmol/l)
Mean (s.e.m.)	1.13 (0.003)	1.23 (0.002)	1.33 (0.003)
Vitamin D (ng/ml)
Mean (s.e.m.)	27.59 (1.06)	29.64 (0.36)	29.02 (1.18)
Femoral neck bone mineral density (gm/cm2)
Mean (s.e.m.)	0.83 (0.01)	0.82 (0.003)	0.80 (0.01)
Albumin (g/l)
Mean (s.e.m.)	39.92 (0.48)	41.12 (0.21)	42.16 (0.25)