Establishment and characterization of a rat model of hyperphosphatemia

We established a rat model of hyperphosphatemia and investigated the systemic effects of high phosphorus (P). Sprague Dawley rats were randomly divided into high (HP), low (LP), and normal (NP) P groups (N = 12 each), which received injections of fructose diphosphate sodium, or were fed self-manufactured low phosphorus or normal diets, respectively. In each group, 4 rats were sacrificed at the first, third, and sixth week to detect the serum (Scr) and urinary creatinine and P, and calcium (Ca) levels. The HP group's serum P and intact parathyroid hormone (iPTH) were significantly higher than those in the other groups at the first, third, and sixth weeks, (P < 0.05); the LP group's serum P was lower than the NP group's at the third week (P < 0.05), while at the sixth week, the serum P and iPTH were lower (P < 0.05). No significant differences were detected for blood Ca+ (P > 0.05). The HP group's Scr increased (P < 0.01), whereas the fractional excretion decreased (P < 0.05) significantly. Thighbone and lumbar spine bone densities differed significantly between groups in the third week (P < 0.05); LP group densities were lower than NP group measures (P < 0.05). Crystallized stones were not observed microscopically following hematoxylin and eosin staining of the kidney. We successfully established a hyperphosphatemia rat model, and high blood P was found to significantly influence renal function and bone density. These results might provide a foundation to study the effects of hyperphosphatemia in rats.