Failure of pH to predict ionized calcium percentage in healthy horses.

The research article discusses a study conducted to determine if there is a correlation between the blood/serum/plasma ionized calcium concentration and pH value in healthy horses. Despite finding some individual significant correlations, no significant relationship between overall serum pH and ionized calcium percentage was found.

Background and Objective

• The aim of the research was to comprehensively evaluate possible correlation between serum pH and ionized calcium percentage in the blood, serum, and plasma in healthy horses. This was performed to discern if pH could be utilized as a reliable predictor for ionized calcium levels.

Methodology

• The study gathered sample materials from 39 healthy horses; including blood, serum, and plasma.
• They assessed total calcium concentrations and plasma and serum ionized calcium concentrations using a calcium-specific electrode.
• In vitro manipulation of pH values in serum samples through the addition of hydrochloric acid or sodium hydroxide was performed to see the effect on ionized calcium concentration.
• The relationship between serum ionized calcium percentage and serum pH at specified pH values were examined using a repeated-measures multiple regression analysis.

Findings

• The research team did not find a significant correlation between serum ionized calcium percentage and serum pH.
• There was, however, a weak correlation between plasma ionized calcium percentage and plasma pH.
• Further manipulation of serum to obtain different pH values showed highly significant correlations between serum ionized calcium percentage and adjusted serum pH value for each horse individually. However, this was not replicated when data from all horses were pooled together.

Conclusion

• Given the results, the study concluded that there is no significant relationship between the serum pH and ionized calcium percentage in healthy horses across the board.
• It was noted that the lack of correlation could be due to variance of ionized calcium percentage among horses, possibly due to differing biochemical constituents in their serum that affect calcium binding equilibrium.
• The study concludes by recommending that direct measurement of serum ionized calcium concentration be employed when needing to evaluate the calcium status of a horse.