Severe hyperphosphatemia resulting from the use of laxatives and enemas with high levels of phosphate has been the subject of many case reports. These have generally focused on the hypernatremia and hypocalcemia that develop and become life-threatening. Less attention has been paid to the metabolic acidosis of phosphate intoxication.
In-depth analysis of a case of severe hyperphosphatemia and review of the literature for cases with sufficient data to permit correlation between the phosphate concentration, acidosis, and anion gap.
Marked metabolic acidosis with a large increase in the anion gap was present in our patient. The correlation between these parameters and the plasma phosphate concentration was highly significant. Despite a paucity of data in most case reports, we did uncover other cases of anion gap–positive metabolic acidosis in patients with hyperphosphatemia.
Among high-risk patients, including the elderly and debilitated, the presence of metabolic acidosis, hypernatremia, an increased anion gap, and low plasma calcium levels or a prolonged QT interval on the electrocardiogram should raise suspicion of phosphate intoxication.
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Top, Correlation between the anion gap and plasma phosphate concentration using the data from the case reported. The regression equation was: y=1.32x+15.5 (R2=0.89). Bottom, Correlation between the anion gap and plasma phosphate concentration using the data from Wason et al.2 The regression equation was: y=0.945x+12.7 (R2= 0.89), with x representing the independent variable and y the dependent variable.
Correlation between the measured pH and the pH calculated from the formula: pH=7.15+(total carbon dioxide concentration/100) using the data from the reported case. Line of identity is shown. The regression equation was: y=0.375x+4.5 (R2=0.81) with x representing the independent variable and y the dependent variable.
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