Study of bone turnover in elder men

ABSTRACT

To evaluate the correlation of serum testosterone with the markers of bone turnover serum alkaline phosphatase and serum osteocalcin as markers of bone formation and urinary deoxypyridinoline to creatinine ratio [DPD/Cr] as a marker of bone resorption in elderly men. Subjects and To achieve this goal, we selected 20 healthy men aged from 60 to70 years [M1], and 10 aged above 70 [M2]. All were with body mass index [BMI] of less than 25 kg/m2 to exclude the effect of increased BMI on bone turnover. Any subject with a systemic disease or on a drug that could affect bone metabolism was excluded. Ten healthy young men served as controls [C], All subjects were subjected to thorough history taking, thorough clinical examination and laboratory investigations in addition to some bone remodeling markers [serum ALP, serum osteocalcin, and urinary DPD/Cr ratio] and serum testosterone, The mean level of serum total alkaline phosphatase was significantly higher in the elderly groups, although it did not exceed the normal range [P<0.001]. Mean serum osteocalcin level was significantly higher in both elderly groups than that in the young group, and its mean level was also significantly higher in M2 group as compared to that in Ml group [P<0.001]. Mean urinary DPD/Cr levels were significantly higher in M1 and M2 groups as compared to those in group C [P<0.001]. Again, its mean level in M2 group was still significantly higher than that in M1 group [P <0.001]. Mean serum testosterone levels in both elderly groups were significantly lower than those in the young group [P< 0.001]. Its mean level in M2 group was also significantly lower than that in M1 group [P <0.005]. A significant negative correlation was found between serum testosterone and all markers of bone turnover under study in M2 group [P<0.05]. However, in M1 group, there was a significant negative correlation between serum testosterone and both urinary DPD/Cr ratio [P<0.001] and serum ALP [P<0.05], but not with serum osteocalcin [P>0.05]. This indicates that the correlation between serum testosterone and osteocalcin attains a significant level with advancement of age. Again, a significant positive correlation was displayed between urinary DPD/CR ratio and both serum ALP and serum osteocalcin [P<0.001] in M1 group. In M2 group, this positive correlation attained a statistical significance with serum ALP [P<0.05], but not with serum osteocalcin [P>0.05]. Conclusions: Serum ALP, serum osteocalcin and urinary DPD/Cr ratio are increased in elderly men above the age of 60 and become higher with advancement of age indicating that bone turnover is a progressive process with aging. Serum testosterone is significantly lower in elderly men. A significant negative correlation was observed between serum testosterone and bone turnover markers in elderly men. Correction of testosterone deficiency may have an important role in prevention of osteoporosis in men