A 24-year-old man was accepted to graduate school in the United States. Before l

Question

A 24-year-old man was accepted to graduate school in the United States. Before leaving home, he had an extensive physical exam that included various blood tests. When the medical staff at the US university reviewed his medical records, it was noted that all test results were normal except the HCO3, which was 15 mmol/L (reference range, 22 to 26 mmol/L). The HCO3 was done separately on a serum sample. It was not part of a blood gas panel, which was not performed on this patient in his home country. To rule out non-respiratory acidosis, the university physician wanted the HCO3 repeated. The repeated value was 24 mmol/L.

Was the initial assumption of a non-respiratory acidosis valid? (Should they have made the diagnosis of non-respiratory acidosis based on the HCO3 result from his home country?) Why or why not?

What would be a better description of the acid-base disturbance?

Why, on repeat testing in the US, do you think the HCO3 returned to normal? (Think about possible differences between the Himalayas and the US).

Explanation / Answer

No, the initial assumption of a non-respiratory acidosis is not valid. The text does not state where the student hails from (we only get a hint that he is probably from the Himalayas) but serum HCO3 can vary a lot with geographical location.

A better description of his condition (assuming that he is from Himalayas) would be hypobaric acidosis.

The ambient atmospheric pressure in the Himalayas (high altitude) is much lower than in the US. As a result the partial pressure of CO2 (pCO2) is also lower, which, in turn, keeps the serum HCO3 low. In the US, the student found himself in normal atmospheric pressure and pCO2, and hence, serum HCO3 also returned to normal.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.