NBME 24 Answers ↦
It looks like it was a type II RTA. The difference is incredibly subtle from the info given in this question.
He has Fanconi syndrome which is generalized reabsorption defect in PCT which leads to metabolic acidosis and hypophosphatemia → can lead to rickets
Also, does lead to type II RTA
Also the proximal tubule is the place with the highest phosphate absorption rate. That's why PTH works here mostly and a little bit in the distal tubule.
Another easy way to go about this one is the question tells you he has metabolic acidosis, the only that can happen with is Fanconi/Type2 RTA. The rest will cause hypokalemia and metabolic ALKALOSIS. (pg 586 FA)
Personally thought if they were going for Fanconi syndrome they would describe a lot more symptoms for the kid like growth failure or hypophosphatemic rickets but its NBME so.