From the Guidelines
Interstitial nephritis is typically associated with metabolic acidosis, not alkalosis. This condition occurs because interstitial nephritis damages the renal tubules, impairing the kidney's ability to excrete acid and reabsorb bicarbonate, as mentioned in the context of acute kidney disease and renal recovery 1. The inflammation in the kidney's interstitium disrupts normal tubular function, particularly affecting the proximal tubule where most bicarbonate reabsorption occurs. Key factors to consider include:
- The mechanism of nephrotoxicity, whether from direct tubular toxicity or interstitial nephritis, should be considered in the context of the functional phase of acute kidney disease (AKD) 1.
- Assessment of the medication regimen comprises several components, including the disposition and effects of drugs administered to patients with AKD, which are modulated by changes in drug clearance and altered pharmacokinetic parameters due to decreased kidney function, such as volume overload and metabolic acidosis 1. As a result, patients develop a normal anion gap metabolic acidosis, often characterized by decreased serum bicarbonate levels, low blood pH, and compensatory respiratory changes like increased respiratory rate. The severity of the acidosis generally correlates with the extent of kidney damage. In some cases, patients may also develop features of renal tubular acidosis (particularly Type 1 or Type 4) depending on which specific tubular segments are most affected by the inflammatory process. Treatment focuses on addressing the underlying cause of interstitial nephritis, such as withdrawing offending medications or treating infections, while managing the acidosis with oral bicarbonate supplementation if necessary.
From the Research
Interstitial Nephritis and Acid-Base Disturbances
- Interstitial nephritis is often associated with characteristic and detectable partial tubular disorders, including diminished H(+) secretion with metabolic acidosis 2.
- The condition leads to inadequate high urinary pH, indicating a tendency towards metabolic acidosis rather than alkalosis 2.
- In contrast, metabolic alkalosis is a widespread acid-base disturbance characterized by the primary elevation of serum bicarbonate and arterial pH, along with a compensatory increase in Pco2 3, 4, 5.
- However, interstitial nephritis is specifically linked to metabolic acidosis, as evidenced by diminished H(+) secretion and inadequate high urinary pH 2.
- The pathogenesis of metabolic acidosis in interstitial nephritis involves impaired kidney function, leading to acid retention and metabolic acidosis 6.
- While metabolic alkalosis can occur in various clinical states, interstitial nephritis is not typically associated with this condition 3, 4, 5.