Posttransplant bone disease: a case illustrating dramatic improvements in bone density with vitamin D replacement therapy

Vitamin D insufficiency does not affect response of bone mineral density to alendronate

SUMMARY

We investigated whether osteoporosis therapy with alendronate in postmenopausal patients is equally effective in patients who are vitamin D insufficient as in those who are vitamin D sufficient. We found that vitamin D insufficiency is common among patients with low bone density but that vitamin D insufficiency did not impair response to alendronate.

INTRODUCTION

Treatment of vitamin D deficiency leads to significant improvements in bone mineral density (BMD); however, whether insufficiency affects BMD's response to bisphosphonate therapy is unknown.

METHODS

To determine whether vitamin D insufficiency at initiation of alendronate therapy for low BMD affects treatment efficacy, we used data from 1,000 postmenopausal women randomly selected from the vertebral fracture arm (n = 2,027) of the placebo-controlled Fracture Intervention Trial of alendronate. Participants were randomly assigned to placebo (50%) or alendronate therapy and most (83%) to calcium (500 mg/day) and cholecalciferol (250 IU/day). We measured serum 25-hydroxy vitamin D (25OHD) at enrollment, then categorized baseline vitamin D status according to 25OHD concentration (<or= 10 ng/ml = deficient; >10 but <or= 30 ng/ml = insufficient; >30 ng/ml = sufficient) and used linear regression to compare the effects of alendronate treatment among these categories.

RESULTS AND CONCLUSION

At baseline, participants were vitamin D sufficient (14%), insufficient (83%), and deficient (2%). We found that BMD response to therapy at total hip or spine did not vary by vitamin D status at baseline (p for heterogeneity = 0.6). We determined that vitamin D insufficiency is common among participants with low BMD. However, vitamin D status at initiation of therapy does not affect BMD's response to alendronate, when it is coadministered with cholecalciferol and calcium.

Calcium and Phosphorus Metabolism Disturbances After Renal Transplantation

INTRODUCTION

Several studies have noted that, despite beneficial correction of abnormalities of mineral metabolism after successful renal transplantation, renal functional recovery is incomplete. Also, persistence of hyperparathyroidism and metabolic acidosis among patients with chronic impairment of graft function together with the use of loop diuretics and immunosuppressive drugs with adverse effects may alter mineral metabolism. We determined calcium and phosphorus levels in recipients.

METHODS

This cross-sectional study enrolled 398 recipients in 2 medical centers in Iran from 1988 to 2004 to evaluate serum calcium and phosphorus levels after 1 month in relation to graft and patient survivals. Cyclosporine was the constant part of the immunosuppressive treatment in all study subjects.

RESULTS

The median follow-up time was 8 months (range, 1-180 months). One and 10-year survival rates of patients were 97.9% and 91.1%. Mean (SD) serum calcium levels before and after transplantation were 8.79 (1.26) and 8.50 (1.39) mg/dL, respectively (P=.020). The mean (SD) phosphate levels before and after transplantation were 6.43 (2.42) and 3.64 (1.71) mg/dL, respectively (P=.000). There was no significant difference in survival considering changes in serum calcium and phosphorus levels. There was no correlation between serum calcium and phosphorus level changes among study patients.

CONCLUSIONS

Despite reports suggesting hypercalcemia as a posttransplantation finding, we did not observe this condition, but, consistent with other reports in this field, we observed a significant decrease in serum phosphorus levels showing correction of this mineral level.