METABOLIC ACIDOSIS-DIFFERENTIALS

SUMMARY

CAUSES OF NORMAL ANION GAP ACIDOSIS (dec HCO₃^- +inc Cl^-)
1. Loss of HCO₃^- due to diarrhea or proximal RTA
2. Increased organic acids (NH₄⁺; e.g., patients on total parenteral nutrition)
3. Increased endogenous acids (inability of the kidneys to excrete endogenous acids: renal failure or distal RTA)

CAUSES OF HIGH ANION GAP ACIDOSIS (dec HCO₃^-, no change in Cl^-)
1. Severe CKD: decreased acid excretion (especialy NH₄⁺)
2. Uremia: causes accumulation of sulfate, phosphate, urate
3. Ketoacidosis: diabetic, alcoholic, starvation
4. Lactic acidosis: drugs, toxins, circulatory compromise
5. Poisonings: salicylates, methanol, ethylene glycol, propylene glycol

Reference(s)

Wilkinson, I. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].