# Renal Tubular Acidosis: Locate the Defect

Follow growth in children, bone health, nephrolithiasis, potassium, and bicarbonate. A diagnostic label should explain the patient's chemistry and clinical trajectory.

![Infographic: Renal Tubular Acidosis: Locate the Defect](https://urinenephrology.org/visual-reference/images/student-renal-tubular-acidosis.png?v=20261003c)

## Normal-gap acidosis

RTA reflects impaired renal acid handling that is disproportionate to the overall reduction in filtration. First confirm a metabolic acidosis and evaluate common nonrenal losses.

## Use potassium as a clue

Low potassium often accompanies distal or proximal tubular defects; hyperkalemia suggests impaired aldosterone action or related physiology. These are patterns, not universal diagnostic rules.

## Interpret urine during acidosis

During systemic metabolic acidosis, persistently alkaline urine supports distal acidification failure after excluding urease-positive infection and confounders. Proximal RTA can produce acidic urine once plasma bicarbonate falls below the reabsorptive threshold. Urine pH alone therefore cannot exclude proximal RTA.

## Use potassium and companion losses

Hyperkalemia directs attention toward impaired aldosterone action, medications, diabetes, or obstruction. Hypokalemia with glycosuria despite normal blood glucose, phosphate wasting, and other solute losses suggests a proximal Fanconi process. Diarrhea remains an important nonrenal cause of normal-gap acidosis.

## Match treatment to physiology

Correct the underlying cause and replace alkali or potassium as appropriate. Hyperkalemic forms require attention to medication effects, potassium balance, and distal sodium delivery.

## Watch for complications

Follow growth in children, bone health, nephrolithiasis, potassium, and bicarbonate. A diagnostic label should explain the patient's chemistry and clinical trajectory.

## Source lessons

- [rta student handout](https://urinenephrology.org/student-resources/electrolyte-acid-base/rta-student-handout.html)
- [tubular disorders student handout](https://urinenephrology.org/student-resources/pediatric/tubular-disorders-student-handout.html)

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