# Metabolic Alkalosis: Generation Plus Maintenance

Assess pH, ventilation, potassium, magnesium, blood pressure, and the clinical trajectory. A numerical improvement should correspond to safer physiology.

![Infographic: Metabolic Alkalosis: Generation Plus Maintenance](https://urinenephrology.org/visual-reference/images/mastery-alkalosis.png?v=20261003c)

## Two processes sustain alkalosis

Acid loss or alkali gain generates the disturbance; chloride depletion, potassium depletion, low effective circulating volume, or impaired excretion can maintain it.

## Recognize the context

Vomiting, gastric drainage, diuretics, mineralocorticoid effects, and excess alkali are common pathways. Mixed respiratory or metabolic disorders may coexist.

## Branch on urine chloride

Urine Cl <20 mEq/L supports chloride depletion, such as vomiting or a remote diuretic effect. At ≥20 mEq/L, assess BP and volume: hypertension suggests mineralocorticoid activity; normal/low BP suggests active diuretics or renal salt-wasting disorders. This is a physiological branch, not a stand-alone diagnosis.

## Replace only what the circulation can accept

For chloride depletion with appropriate volume tolerance, chloride and potassium replacement can remove factors maintaining alkalosis. A congested patient may require potassium chloride and a revised diuretic strategy rather than routine saline. Treat ongoing vomiting, excessive alkali, or a mineralocorticoid cause.

## Recognize when the branch is unreliable

Active or recent diuretics can raise urine chloride despite depletion; repeat interpretation after accounting for dose timing. CKD G4–G5 limits reliance on a single spot urine chloride. Reassess magnesium, potassium, blood gas, urine findings, and treatment response before assigning a fixed chloride-responsive/resistant label.

## Follow more than bicarbonate

Assess pH, ventilation, potassium, magnesium, blood pressure, and the clinical trajectory. A numerical improvement should correspond to safer physiology.

## Supporting evidence

- [Supporting guideline or source](https://pmc.ncbi.nlm.nih.gov/articles/PMC10947768/)
- [Supporting guideline or source](https://pmc.ncbi.nlm.nih.gov/articles/PMC11173655/)

## Source lessons

- [metabolic alkalosis](https://urinenephrology.org/mastery/electrolytes-advanced/metabolic-alkalosis.html)

Read alongside the full lessons; the findings and decisions shown here require the stated clinical context.