Rapid Correction of Metabolic Acidosis in Chronic Renal Failure: Effect on Parathyroid Hormone Activity

Abstract

To investigate the effect of rapid correction of chronic metabolic acidosis on circulating intact parathyroid hormone (I-PTH) activity by free calcium clamp in chronic renal failure, 18 patients were enrolled in this study. Metabolic acidosis was corrected by continuous bicarbonate infusion while plasma ionized calcium was clamped at the preinfusion level throughout the entire procedure. The plasma pH, bicarbonate, total CO₂, sodium, serum total calcium and 1,25(OH)₂vitamin D₃ levels increased significantly while serum concentrations of I-PTH, alkaline phosphatase and albumin showed significant decreases after bicarbonate infusion. The plasma ionized calcium, potassium, serum magnesium and inorganic phosphorus levels showed no significant difference before and after bicarbonate infusion. These results demonstrate that rapid correction of metabolic acidosis attenuates circulating PTH activity in chronic renal failure and may underline the importance of maintaining normal acid-base homeostasis particularly in the presence of secondary hyperparathyroidism.

Direct Effect of Acute Metabolic and Respiratory Acidosis on Parathyroid Hormone Secretion in the Dog

“…Although our results in acute Met Acid are similar to those in previous studies, those studies did not control for acidosis‐induced changes in the plasma calcium concentration (1,2,5) . In a study that reversed the sequence and corrected Met Acid while controlling for changes in ionized calcium, the rapid correction of Met Acid reduced PTH values (31) . In acute Resp Acid, in contrast to the study by Canzanello et al, (6) we showed that PTH values did increase.…”

Posttransplant Acidosis and Associated Disorders of Mineral Metabolism in Patients With a Renal Graft

“…Acidosis induces calcium excretion (34) and reduces vitamin D synthesis (29) which, in turn stimulate PTH release. Accordingly, correction of metabolic acidosis has been shown to reduce PTH levels (35), probably through increased sensitivity of the parathyroid glands to calcium (36). On the other hand, evidence suggests, that PTH promotes metabolic acidosis through inhibition of bicarbonate reabsorption from the glomerular filtrate (37) and alterations in renal phosphate handling (38).…”

Metabolic acidosis-induced hypercalcemia in an azotemic patient with primary hyperparathyroidism

“…The failure of hypercalcemia to suppress PTH could have been from stimulation of PTH secretion by metabolic acidosis. Acute metabolic acidosis has been shown to increase PTH secretion in animals [ 4 , 5 ] and correction of metabolic acidosis to decrease PTH secretion in azotemic humans [ 6 , 19 ]. Also, how much of the measured PTH is actually intact PTH is difficult to know because as renal failure progresses the PTH assay also measures large, truncated amino-terminal PTH fragments [ 20 , 21 ].…”