2014-18 Metabolic acidosis Ketoacidosis Lactic acidosis Accumulation of endogenous acids(high anion gap) External losses of bicarbonate(normal anion gap hyperchloremic) Anion Gap Anion Gap ·AG=Na- Cl'-HCO3=12±2 will reduce ag charged. Presence of large amount orOsitive Renal failure Renal failure With mild to moderate reductions in gfR. the acidosis reflects decreased ammoniagenesis and is Despite a daily net positive acid balance it is unusual therefore hyperchloremic for [HCO3-to fall lower than 15 mmol/L. As kidney failure worsens, the calcium and a negative calcium balance ulfate phosphate, and other anions, produces an Chronic acidosis causes protein breakdown, muscle wasting, and a negative nitrogen balance. maintenance of the acid-base balance close to ormal can prevent these consequences2014-1-8 4 Metabolic acidosis • Influx of organic acid into plasma (high anion gap) – Ketoacidosis – Lactic acidosis – Poisoning • Accumulation of endogenous acids (high anion gap) – Renal failure • External losses of bicarbonate (normal anion gap; hyperchloremic). – GI loss – Renal loss Anion Gap • AG=Na+ -Cl- -HCO3- = 12±2 • albumin: negative charged. Low serum albumin will reduce AG. • Paraprotein (Ig or light chains, MM): positive charged. Presence of large amount of paraprotein reduces AG. Anion Gap Renal failure • With mild to moderate reductions in GFR, the acidosis reflects decreased ammoniagenesis and is therefore hyperchloremic. • As kidney failure worsens, the kidney loses its ability to excrete various anions, and the accumulation of sulfate, phosphate, and other anions, produces an elevated AG. Renal failure • Despite a daily net positive acid balance, it is unusual for [HCO3−]to fall lower than 15 mmol/L. • The buffering of protons by bone results in loss of calcium and a negative calcium balance. • Chronic acidosis causes protein breakdown, muscle wasting, and a negative nitrogen balance. • Maintenance of the acid-base balance close to normal can prevent these consequences