Case #4

1. What is the primary acid-base abnormality? 

Metabolic acidosis

2. Calculate his anion gap.  Is there an increase in the anion gap? 

104 – (16 + 112) = 12

3. He has normal anion gap metabolic acidosis.  What is the hydrogen ion concentration? 

( 24) (30) = 45 nM/L
      16

4. Is there a compensatory mechanism for this abnormality? 

Hyperventilation

5. What is the predicted compensatory response?

 (25 – 16) x 1.2 = 10.8; expected P _co2 = 40mmHg – 10.8 mmHg) = 29.2 mmHg + 2 mmHg

6. Is this disorder simple or mixed?

 Simple

7. What are the common causes for non-anion gap metabolic acidosis?

• Normal anion gap

  • abnormally high bicarbonate loss

    • Kidney fails to reabsorb

      • renal tubular acidosis

    • Kidney fails to regenerate

      • Diuretics

    • extra renal loss of bicarbonate

      • Diarrhea

      • ileal drainage

    • acidifying salts have been added

      • hyperalimentation

      • ammonium chloride

8. What clinical condition(s) is (are) responsible for the acid-base disturbance in this patient? Explain your logic.

 Most likely the presence of a type IV RTA.

9. What are the physiologic mechanisms responsible for the generation of this disturbance?

The nonanion gap acidosis is due primarily to a decreased production and/or decreased response of aldosterone at the cortical collecting duct.