Is ur father diabetic? How high did the
creatinine go during the AKI?
As it's been 3 months, it is unlikely that the creatinine wil go back to 1.3. But it may slowly decrease over the next few months.
Meanwhile it is very important to avoid other injuries to
kidney, in the form of painkillers and further infections.
Phosphorous of 5.3 is expected for this level of creatinine.
But he will need medications if it's persistently high
Next Steps
consult for further opinion