Department of Nephrology, Towa Hospital, Adachi-ku, Tokyo, Japan.
J Bone Miner Res. 2010 Nov;25(11):2374-81. doi: 10.1002/jbmr.126.
In order to gain insight into the mechanisms underlying the dynamic changes in bone metabolism and bone quality after parathyroidectomy (PTX) in secondary hyperparathyroid patients with high levels of parathyroid hormone (PTH), we performed bone histomorphometric analysis with tetracycline labeling in iliac bone biopsy specimens taken before and after PTX, with special attention paid to osteocytes. At 2 to 4 weeks after PTX, PTH concentrations decreased markedly with evident reductions in bone turnover markers. Histomorphometry revealed that at 2 to 4 weeks following PTX, the osteoclast surface decreased to nearly 0%, with a substantial increase in osteoid volume and a reduction in fibrosis volume. Labeling with tetracycline was observed not only at the mineralization front on the bone surface but also around the osteocyte lacunar walls and canaliculi within both the basic multicellular units (BMUs) and bone structural units (BSUs), suggesting that mineralization was taking place along the lacunocanalicular system after PTX. The tetracycline-labeled area was much greater in the BSUs than in the BMUs and at the mineralization front, and the tetracycline labeling in the BSUs was markedly increased after PTX compared with that in the low- and high-PTH control groups without PTX. The osteocyte number was decreased significantly after PTX, concomitant with an increase in the number of empty lacunae and a reduction of lacunar volume. Thus the increased osteocyte death and mineralization around the lacunocanalicular system in association with a rapid decline in PTH may underlie the changes in bone metabolism and quality that occur following PTX.
为了深入了解甲状旁腺激素（PTH）水平较高的继发性甲状旁腺功能亢进患者甲状旁腺切除术后（PTX）骨代谢和骨质量动态变化的机制，我们对术前和术后取自髂骨的骨组织学标本进行四环素标记的骨组织形态计量学分析，特别关注破骨细胞和骨细胞。在 PTX 后 2 至 4 周，PTH 浓度显著下降，骨转换标志物明显减少。组织形态计量学显示，PTX 后 2 至 4 周，破骨细胞表面几乎降为 0%，类骨质体积显著增加，纤维化体积减少。四环素标记不仅在骨表面矿化前沿观察到，而且在基本多细胞单位（BMU）和骨结构单位（BSU）内的骨细胞腔隙和小管周围也观察到，表明 PTX 后沿骨陷窝小管系统发生矿化。BSU 中的四环素标记区域明显大于 BMU 和矿化前沿，PTX 后 BSU 中的四环素标记明显增加，高于未进行 PTX 的低 PTH 和高 PTH 对照组。PTX 后骨细胞数量明显减少，同时空骨陷窝数量增加，骨陷窝体积减少。因此，破骨细胞死亡和陷窝小管系统周围矿化的增加与 PTH 的快速下降可能是 PTX 后骨代谢和骨质量变化的基础。
