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Table 3 Serum PTH in relation to calcium and vitamin D intakes in all subjects and gender specific in 1917 subjects in the sub-study

From: Increased calcium intake is associated lower serum 25-hydroxyvitamin D levels in subjects with adequate vitamin D intake: a population-based observational study

  Calcium intake§ < 500 mg/d Calcium intake§ 500–999 mg/d Calcium intake§ 1000–1499 mg/d Calcium intake§ > 1499 mg/d
n Serum PTH (pmol/L) n Serum PTH (pmol/L) n Serum PTH (pmol/L) n Serum PTH (pmol/L)
All subjects‡
 Vitamin D intake (ug/d)§
   < 7.0 86 6.3 (5.8, 6.9) 230 5.9 (5.6, 6.2) 125 5.8 (5.5, 6.2) 53 5.7 (5.0, 6.5)
  7.0–13.9 44 6.6 (5.7, 7.4) 225 5.9 (5.7, 6.2) 236 5.9 (5.6, 6.1) 119 6.0 (5.6, 6.4)
  14.0–20.9 15 7.4 (5.0, 9.8) 85 5.8 (5.4, 6.3) 130 5.6 (5.3, 6.0) 104 5.8 (5.3, 6.2)
   > 20.9 16 5.7 (4.5, 6.9) 143 5.7 (5.4, 6.1) 151 5.4 (5.0, 5.9) 155 5.3 (5.1, 5.6)
Males‡
 Vitamin D intake (ug/d)§
   < 7.0 28 6.9 (5.6, 8.2) 92 5.8 (5.4, 6.2) 44 5.8 (5.2, 6.5) 19 5.9 (4.4, 7.5)
  7.0–13.9 21 7.0 (5.4, 8.6) 103 6.1 (5.6, 6.6) 107 6.0 (5.6, 6.4) 66 6.1 (5.6, 6.7)
  14.0–20.9 4 5.7 (4.4, 6.9) 33 5.6 (4.9, 6.4) 56 5.6 (5.0, 6.2) 50 6.1 (5.4, 6.8)
   > 20.9 4 5.7 (1.2, 9.5) 68 5.6 (5.2, 6.0) 62 5.6 (4.5, 6.7) 71 5.2 (4.9, 5.6)†
Females‡
 Vitamin D intake (ug/d)§
   < 7.0 58 6.1 (5.6, 6.6) 138 6.0 (5.6, 6.4) 81 5.8 (5.4, 6.2) 34 5.6 (4.7, 6.5)
  7.0–13.9 23 6.1 (5.3, 6.9) 122 5.8 (5.5, 6.1) 129 5.8 (5.4, 6,2) 53 5.8 (5.2, 6.4)
  14.0–20.9 11 8.0 (4.7, 11.4) 52 6.0 (5.3, 6.6) 74 5.7 (5.3, 6.1) 54 5.4 (5.0, 5.9)#
   > 20.9 12 5.7 (4.2, 7.2) 75 5.8 (5.3, 6.3) 89 5.3 (5.0, 5.7) 84 5.4 (5.0, 5.8)
  1. #P < 0.05. Linear trend for serum PTH across calcium intake groups without adjustments
  2. P < 0.05. Linear trend for serum PTH across vitamin D intake groups without adjustments as well as with sex, age, BMI and month of blood sampling (using dummy variables) as covariates
  3. ‡ Subjects in the Tromsø study with valid food frequency questionnaires, serum 25(OH)D measurement, not been on a sunny vacation last 2 months, not taking solarium regularly, with valid serum PTH measurement, and with serum calcium < 2.51 mmol/L.
  4. § Including supplements
  5. The data are mean (95% CI). The P values are adjusted for multiple testing with a factor of 4