Moderate strontium loading induces rickets in rats with mild chronic renal failure

Renal osteodystrophy and eventually osteoporosis are serious long-term complications in children with end-stage renal disease before and after renal transplantation. Strontium (Sr) salts are used for treatment of osteoporosis in adults.

To evaluate the time-dependent effects of Sr on growth plate morphology and their reversibility, chronic renal failure (CRF) rats received either normal or Sr-loaded drinking water (2 g/l; ±200 mg/kg/day) for periods of 2, 6 and 12 weeks with or without subsequent washout periods of 0, 2, 4 or 8 weeks.

While weight gain was not affected by Sr loading, a significant enlargement of the entire growth plate, mainly due to expansion of the hypertrophic zone, was already present after 2 weeks. Sr-loaded animals showed increased osteoid areas and reduced bone formation rates at 2, 6 and 12 weeks compared to controls. This was accompanied by reduced PTH levels and increased serum bone alkaline phosphatase activity. After the washout periods these effects were reversed. In general, the height of the hypertrophic zone was positively correlated with osteoid area and negatively correlated with bone formation rate.

Moderate Sr loading in CRF rats results in rapid development of rickets, which is reversible after washout.