Change in serum bicarbonate during acute EDTA infusions in post-transplant hyperparathyroidism

We evaluated the effect of endogenous parathyroid hormone (PTH) on serum bicarbonate in 12 patients with postrenal transplant hyperparathyroidism. EDTA-induced hypocalcemia produced a significant rise in serum PTH (p less than 0.001). Associated with the increase in PTH was a significant fall in plasma bicarbonate (p less than 0.001) and increase in the chloride: phosphorus ratio (p less than 0.001). Magnesium remained stable but serum potassium fell in response to EDTA. These observations suggest that endogenous PTH can significantly affect plasma bicarbonate in vivo and may contribute to post renal transplant renal tubular acidosis.