Review of the Diagnostic Evaluation of Renal Tubular Acidosis

Abstract

Background: The term renal tubular acidosis (RTA) describes a group of uncommon kidney disorders characterized by defective acid-base regulation. Reaching the diagnosis of RTA is complex and often delayed, resulting in suboptimal treatment.

Methods: This article provides an overview of the clinical features of RTA and diagnostic approaches in a format accessible to physicians for everyday use.

Results: The 3 major forms of disease are classified by their respective tubular transport defects, each of which produces persistent hyperchloremic metabolic acidosis. Distal RTA is characterized by limited urinary acid secretion, proximal RTA by restricted urinary bicarbonate reabsorption, and hyperkalemic RTA by absolute or relative hypoaldosteronism. RTA is often detected incidentally as a biochemical diagnosis in asymptomatic individuals. When present, clinical features may range from mild nonspecific complaints to life-threatening physiologic disturbances.

Conclusion: RTA is a complex condition that requires thoughtful investigation. Physicians should be aware of the presentation of RTA and the investigative options available to confirm the diagnosis.

Keywords: Acid-base equilibrium; acidosis; acidosis–renal tubular.

Figure 1.

Suggested algorithm for suspected renal tubular acidosis (RTA) in patients with non–anion gap metabolic acidosis and hypokalemia. HCO₃⁻, bicarbonate; UAG, urine anion gap.

Figure 2.

Suggested algorithm for suspected renal tubular acidosis (RTA) in patients with non–anion gap metabolic acidosis and hyperkalemia.