Table 11.9-4. Approaches to renal tubular acidosis

Feature

pRTA (type 2 RTA)

dRTA (type 1 RTA)

Type 4 RTA

Degree of acidosis

Moderate

Severe

Mild

Minimal urine pH (during acidosis)

<5.5

>5.5

<5.5

Fractional HCO3− excretion (FEHCO3−) with normal serum HCO3− (after NaHCO3 load)

>15%

 

<3%-5%

 

<3%-15%

 

Nephrocalcinosis

Rarely

Often

Never

dRTA, distal renal tubular acidosis; pRTA, proximal renal tubular acidosis; RTA, renal tubular acidosis.