The occurrence of chronic hypocalcemia following parathyroidectomy in the green frog, Rana clamitans

The plasma calcium concentrations of parathyroidectomized male specimens of the green frog, Rana clamitans, were monitored for 44 or 62 weeks. Plasma total and ionized calcium levels of the parathyroidectomized animals decreased 31-53% within 3 days, continued to fall to approximately 50% of the preoperative levels by Weeks 3-9, and remained at these low levels for the duration of the experiments. Plasma sodium, pH, and hematocrit levels were unchanged. The chronic hypocalcemia resulted in tetanic spasms in all of the long-term parathyroidectomized animals and in the death of most of the long-term parathyroidectomized animals. Thus, in the green frog the presence of the parathyroid gland is required for maintenance of blood calcium levels and for survival.