Evaluation of bone metabolism-associated biomarkers in Tibet, China

Bone mineral metabolism and different indices of skeletal health of Ladakhi women living at high altitude

Objectives

High altitude possesses a great challenge for human survival owing to low oxygen tension and has been reported to cause bone deterioration among sojourns of high altitude. The bone health of Ladakhi women is investigated for the first time in this study.

Methods

Dual energy X-ray absorptiometry of Ladakhi women and sea level women was done at the radius and calcaneus using EXA-3000 (Osteosys, Korea), followed by colorimetric and Enzyme Linked Immunosorbent Assay analysis of parameters regulating bone health.

Results

There was no statistically significant difference between bone mineral density of Ladakhi women and sea level women at radius (P = 0.287) or calcaneus (P = 0.839). Almost similar cases of osteopenia were reported at both sites measured in the study among both groups. Two post-menopausal Ladakhi women however, had osteoporosis at the radius while 4 had osteoporosis at calcaneus. Significant increase in calcium levels with a decrease in intact parathyroid hormone and an increase in calcitonin levels were observed in Ladakhi women as compared to sea level women. Though there was no significant difference in 25-hydroxy vitamin D levels of both groups, a higher percentage of 25-hydroxy vitamin D deficiency (77% vs 23%) was observed in Ladakhi women as compared to sea level women. Estradiol levels were similar in both groups.

Conclusions

The present study suggest that there is no significant relationship between high altitude living and bone mineral density among Ladakhi women.

Evaluation of bone metabolism-associated biomarkers in Tibet, China

Aim

To measure and evaluate the distribution and possible contributing factors of seven bone metabolism‐associated biomarkers in Tibet, a plateau province of China.

Methods

A total of 1615 individuals were recruited from Tibet at three different altitudes. The levels and possible contributing factors of serum calcium, serum phosphorus, ALP, 25OHD, PINP, CTX, and PTH were evaluated.

Results

In total, 1246 Tibetan adults (males: n = 543) were eventually enrolled in this study. Multiple linear regression recognized age, sex, altitude, and BMI as the major effect factors. The levels of ALP, PINP, and CTX in males continuously decreased with age; however, those in females increased after approximately 39 years of age. Males had higher 25OHD levels (23.9 vs. 15.4 ng/ml) but lower levels of serum phosphorus (1.12 vs. 1.19 mmol/L) and PTH (41.3 vs. 47.4 pg/ml) than females. Before the age of 50, males had higher levels of calcium, ALP, PINP, and CTX than females, and the opposite trend was observed after the age of 50. The highest levels of serum calcium and phosphorus and the lowest levels of PINP and CTX were found in the Shigatse/Lhasa region, suggesting a better bone metabolism status. Compared with reports from plain areas of China, significantly higher levels of PINP (65.3 vs. 49.36 ng/ml) and CTX (0.46 vs. 0.37 ng/ml) were recorded in Tibetan adults.

Conclusion

A more active bone turnover status was found in Tibetan adults than in individuals from the plain areas of China.