Interpreting ABG's

Can someone please help me with this question.

ou are caring for a patient with a renal transplant who has come into the ED complaining of light-headedness and epigastric pain. The patient has a blood gas reading pH of 7.50, PaCO2 of 31mmHg, and a HCO3 of 20mmmol/L. The RN notifies the registrar because the patient is most likely experiencing:

a) uncompensated metabolic acidosis

b)uncompensated metabolic alkalosis

c)uncompensated respiratory acisosis

d)uncompensated respiratory alkalosis

For the answer I got compensated respiratory alkalosis.

This is how I figure it out:

pH 7.50- Alkalosis.

PaCO2 31mmHg- Alkalosis.

HCO3 20mmol/L- Acidosis.

pH and PaCO2 match (as in they are both alkalosis). This means it is respiratory relating.

And because the HC03 is acidic it is compensating.

BUT my lecturers answer to this is:

Just to clarify this question

pH 7.50 means it is uncompensated as patient is still in alkalosis

the cause is likely to be metabolic due to his kidney disease

and because the pH is above the reference range of 7.35-7.45 he is in alkalosis

The low pCO2 is due to the hydrogen ions being used up trying to compensate but the pH remains high so is not fully compensated as yet.

Hope that helps.

---- Now I am really confused. Am I working it out wrong?