Neonatal Nurse Practitioner Practice Exam

What conditions are associated with metabolic acidosis that presents with a normal anion gap?

1. Lactic acidosis and acute renal failure

2. Renal tubular acidosis and obstructive uropathy

3. Acute myocardial infarction and liver failure

4. Diabetic ketoacidosis and hypothyroidism

The correct answer is: Renal tubular acidosis and obstructive uropathy

Metabolic acidosis with a normal anion gap typically indicates that the primary disturbance is occurring in the renal handling of bicarbonate or the retention of hydrogen ions, rather than an increase in unmeasured anions, which would raise the anion gap. Renal tubular acidosis is a condition that leads to a defect in the renal tubules' ability to excrete hydrogen ions or to reabsorb bicarbonate, causing a normal anion gap acidosis. Specifically, type 1 (distal) and type 2 (proximal) renal tubular acidosis can cause metabolic acidosis without the marked increase in unmeasured ions that would elevate the anion gap. Obstructive uropathy can also lead to normal anion gap metabolic acidosis. When urine flow is obstructed, it can lead to a build-up of acid in the body as the kidneys fail to effectively excrete hydrogen ions and maintain appropriate bicarbonate levels. Conditions like lactic acidosis or acute renal failure can produce an elevated anion gap and are therefore not associated with normal anion gap metabolic acidosis. Furthermore, diabetic ketoacidosis is characterized by a high anion gap due to the accumulation of ketone bodies. Thus, identifying renal