METABOLIC ALKALOSIS

SUMMARY

1. Metabolic alkalosis commonly results from volume contraction caused by diuretics or vomiting/gastric suction.

2. Metabolic alkalosis always involves a generation phase (initial H⁺ loss or HCO₃^- gain) and maintenance phase (failure of the kidney to excrete HCO₃^- to correct the alkalosis.

3. With vomiting and NG suction, HCl is lost via gastric secretions.

4. With primary hyperaldosteronism, there is renal acid & potassium loss.

5. With diuretic-induced "contraction" alkalosis, there is renal loss of bicarb-free fluid, resulting in reduction in the extracellular fluid volume around a fixed quantity of extracellular bicarbonate.

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].