Severe hypernatremia and hyperchloremia in an elderly patient with IgG-kappa type

Kenrick Berend

St Elisabeth Hospital, Willemstad, Curaçao

Imashuku et al¹ describe a 77-year-old male patient with multiple myeloma who was admitted to the hospital after suffering a pelvic bone fracture due to a road traffic accident. Several days after admission the arterial blood gas showed a pH of 7.481; arterial carbon dioxide tension (PaCO₂) of 28.2 mmHg; arterial oxygen tension (PaO₂) of 84.0 mmHg; HCO₃- of 20.8 mmol/L (normal; 23–31 mmol/L); and an anion gap of 8.9 mmol/L (normal;12 mmol/L). These data, as the authors concluded, were suggestive of metabolic acidosis. First, this is not true because a high pH and low PaCO₂ confirm a respiratory alkalosis. Since the test was conducted days later we may expect a chronic respiratory alkalosis to be present, perhaps because of pain or a secondary pulmonary problem, as may be expected with a relatively low PaO₂. In chronic respiratory alkalosis one would expect the HCO₃- to decrease about 4 mmol/L with every 10 mmHg decrease of PaCO₂.² If the initial HCO₃- had been about 25 mmol/L, the expected PaCO₂ would be about 20.28 mmol/L, almost identical with the patient’s HCO₃-.

View original paper by Imashuku and colleagues.