Significance of time-course changes of serum bone markers after parathyroidectomy in patients with uraemic hyperparathyroidism.

BACKGROUND: The increase of bone mineral density in cortical bone after parathyroidectomy is smaller than that in cancellous bone. Changes of serum bone markers reflect those of bone metabolism both in cortical and cancellous bone after parathyroidectomy. The present study was undertaken to investigate changes of histomorphometric parameters of cortical and cancellous bone together and their correlation with those of serum bone markers. METHODS: Iliac bone biopsy was performed before and 1 week after parathyroidectomy in Group I (n = 13), and before and 4 and 12 weeks after in Group II (n = 11). Moreover, changes of histomorphometric parameters of the endocortical, intracortical and periosteal surfaces as well as in cancellous bone were monitored. Serum levels of intact parathyroid hormone and bone markers were measured simultaneously. Results. In cancellous bone, osteoclast surface (Oc.S/BS) decreased to 0% within 4 weeks after parathyroidectomy, while osteoblast surface (Ob.S/BS) transiently increased at 1 week, followed by a reduction at 4 weeks to levels below the pre-surgical level. In cortical bone, Oc.S/BS was not reduced to 0%, while a significant and temporary increase of Ob.S/BS was observed only on the endocortical and intracortical surfaces at 4 weeks, but not at 1 week. Serum bone resorption markers did not completely disappear and significant and sustained increases of bone formation markers were observed until 4 weeks after parathyroidectomy. CONCLUSIONS: Changes of bone formation markers lagged behind those of histomorphometric parameters in cancellous bone because changes of cortical bone were observed later and were incomplete compared with those of cancellous bone.

[Two cases of hemodialysis patients with absolute hypoparathyroidism or normal parathyroid function who were suffering from prostate carcinoma].

In recent years, the incidence of prostate carcinoma in patients with renal failure is increasing. But it is difficult to diagnose the occurrence of this neoplasm because of decrease of urinary volume in these patients. Two hemodialysis patients (age: 64, 68 years, the duration of hemodialysis: 10, 8 years) suffering from prostate carcinoma were treated with androgen deprivation therapy, which accelerates bone resorption. (This kind of osteoporosis is often treated by bisphosphonate, but this treatment is prohibited in hemodialysis patients.) Both serum testosterone and estradiol went down to the extremely lower levels in these patients. Thereafter, one (case 2) of them was maintained under absolute hypoparathyroidism by the conservative therapy with vitamin D. As a result, bone mineral density of the patient (case 2) was well maintained during one year. In conclusion, hypoparathyroidism was helpful to prevent bone loss in patients receiving androgen deprivation therapy.

Changes of bone remodeling immediately after parathyroidectomy for secondary hyperparathyroidism.

BACKGROUND: Successful parathyroidectomy for secondary hyperparathyroidism alleviates bone pain and is followed by the development of hypophosphatemia and hypocalcemia, as well as an increase in bone mineral density. An increase in osteoblast surface (Ob.S/BS) is not observed several months after surgery. In this study, we investigated early bone changes at 1 week after parathyroidectomy and the mechanism underlying an increase in bone mineral density. METHODS: Fourteen patients with severe secondary hyperparathyroidism underwent iliac bone biopsy before and 1 week after parathyroidectomy. Changes in histomorphometric parameters, including osteoclast surface (Oc.S/BS), eroded surface (ES/BS), erosion depth (E.De), fibrosis volume (Fb.V/TV), Ob.S/BS, osteoid volume (OV/BV), osteoid surface (OS/BS), and osteoid thickness (O.Th), were investigated. Changes in texture of mineralized bone and osteoid seams were also investigated. RESULTS: Oc.S/BS (P < 0.001), ES/BS (P < 0.01), and E.De (P < 0.001) decreased, but Fb.V/TV did not change at 1 week postoperatively. In particular, osteoclasts disappeared in almost all patients. Ob.S/BS (P < 0.001) increased, and cuboidal osteoblasts were proliferating on the trabecular surface where osteoclasts had existed before parathyroidectomy. As a result, newly developed osteoblasts coexisted with fibrous tissue after surgery. OV/BV (P < 0.005), OS/BS (P < 0.005), and O.Th (P < 0.005) increased, with lamellar osteoid volume showing a particular increase. Bone mineralization continued despite the low postoperative serum parathyroid hormone level. CONCLUSION: A rapid decrease in serum parathyroid hormone level after parathyroidectomy appears to suppress bone resorption, as well as cause a transient marked increase in bone formation and an increase in normal lamellar osteoid seams.

[Impact of parathyroidectomy on bone histology].

Impacts of total parathyroidectomy and autotransplantation on bone histology were evaluated in secondary hyperparathyroidism. Low turnover bone disease accompanied with fibrous tissue developed at 4 weeks after surgery, and osteoclasts disappeared. In addition, fibrous tissue also disappeared at 12 weeks. Even though serum PTH level indicated quite low in some cases, bone resorption exceeded bone formation at 1 years after surgery. So we should pay special attention to the decrease in bone mineral density in the long term in these cases.