Application of delta gap equation for the assessment of metabolic acidosis in renal failure patients

Abstract

Introduction: Metabolic acidosis is commonly encountered in chronic kidney disease (CKD) which contributes to its progression. The metabolic acidosis in chronic kidney disease is presumed to be due to accumulation of unmeasured anions leading to a high anion gap (AG). The aim of the study was to assess the metabolic acidosis in renal failure patients using the calculation of delta gap. Methods: 100 renal failure cases were included. Their abnormal urea and creatinine values were utilized to calculate the BUN/creatinine ratio for all the cases. Based on the dipstick urine testing grading, proteinuric renal diseases were identified. The urine and serum osmolality were calculated in these renal failure patients. Serum osmolality was calculated using the values of serum sodium and urea. Urinary density which is also called urine specific gravity was used for indirect calculation of urine osmolality. Modified delta gap equation was applied for quick evaluation of mixed metabolic acid-base disorders. Results: Out of the 100 cases, 41 were proteinuric renal disease cases and 59 were non-proteinuric renal disease cases. High anion gap metabolic acidosis were seen in 65% of the total 100 cases. In 33% of the total cases, non-anion gap metabolic acidosis was also seen in addition to the high anion gap metabolic acidosis as it is evidenced by the delta gap value of less than -6 mmol/L. Conclusions: Earlier identification of the type and causative mechanism of metabolic acidosis in these patients may help to decrease the morbidity and mortality of these patients. The delta gap that can be easily calculated using this quick and short equation at the bedside may serve as a marker in the management of metabolic acidosis in renal failure patients. Keywords: delta gap; modified quick equation; metabolic acidosis; renal failure