Consider the following:
1. Normal anion gap
2. Hyperchloraemic acidosis
3. Inappropriately high urinary pH (>5.4)
Which of the above are the characteristic features of renal tubular acidosis (RTA)?
Renal Tubular Acidosis Features Explained
Renal Tubular Acidosis (RTA) is a condition where the kidneys are unable to properly excrete acids, leading to metabolic acidosis. The key features used for diagnosis are:
Normal Anion Gap in RTA
RTA typically causes metabolic acidosis but is associated with a normal anion gap. This contrasts with other causes of metabolic acidosis, such as ketoacidosis or lactic acidosis, which usually present with a high anion gap.
Hyperchloraemic Acidosis in RTA
A consistent finding in RTA is hyperchloraemic acidosis. This occurs because the impaired kidney function leads to a loss of bicarbonate and retention of acids, resulting in an increase in serum chloride levels to maintain electrical balance.
High Urinary pH in RTA
A characteristic feature, particularly of distal RTA (Type 1), is the inability to lower urinary pH sufficiently. This results in an inappropriately high urinary pH (often $pH > 5.4$) despite the presence of systemic acidosis, indicating impaired distal acidification.
Summary of RTA Features
The presence of all three features – a normal anion gap, hyperchloraemic acidosis, and an inappropriately high urinary pH (greater than 5.4) – collectively indicates Renal Tubular Acidosis.
Important Questions from Acid-Base Disorders
- The most common acid-base disturbance in critically ill patients is :
- Salicylate intoxication in adults usually causes:
1. Severe respiratory alkalosis.
2. Mixed metabolic acidosis respiratory alkalosis.
3. Hyperchloremic metabolic acidosis.
Select the correct answer using the code given below - Which one of the following pairs is not correctly matched?
- Which one of the following is not an example of metabolic acidosis with high anion gap?
- Consider the following statements regarding distal renal tubular acidosis:
1. Blood biochemistry reveals normal anion gap metabolic acidosis
2. There is defective secretion of H$^+$ in the distal tubule.
3. There may be associated muscle weakness and rickets.
4. Children may present with polydipsia and polyuria.
Which of the above statements are correct?
