Age-related changes of urinary pyridinoline and deoxypyridinoline in Japanese subjects

Urinary pyridinoline (Pyr) and deoxypyridinoline (D-Pyr) are commonly used as bone resorption markers because they are more sensitive to bone resorption than is urinary hydroxyproline. Age-related changes of urinary Pyr and D-Pyr were studied in 337 healthy females, aged 1 to 93 y, and 113 healthy males, aged 3 to 75 y. Levels of urinary Pyr and D-Pyr follow a characteristic pattern as one ages, with very high values during childhood decreasing to low baseline levels in adulthood between 20 and 49 y. Both values in the 0-19 y age group were significantly higher than those in the other age groups for both sexes. These values increased moderately but significantly in females in the 50-59 y age group compared to those in the 40-49 y age group (Pyr: 26.4 +/- 7.6 vs. 19.3 +/- 6.2 nmol/mmol creatinine, p < 0.05; D-Pyr: 7.7 +/- 2.4 vs. 5.6 +/- 2.2 nmol/mmol creatinine, p < 0.05). In contrast, these values stayed at low levels in the 50-59 y age group in males. The values of urinary Pyr and D-Pyr were significantly higher in females than in males in the 50-59 y age group (females vs. males--Pyr: 26.4 +/- 7.6 vs. 17.0 +/- 3.9 nmol/mmol creatinine, p < 0.05; D-Pyr: 7.7 +/- 2.4 vs. 4.7 +/- 1.2 nmol/mmol creatinine, p < 0.05). In our cross-sectional study, the values of urinary Pyr and D-Pyr increased in childhood (0-19 y), and in the early postmenopausal period (50-59 y). These 2 urinary markers reflect the age-related changes of bone resorption.