My son had a fbc recently to check he has recovered from itp. The GP very kindly rang to say platelets were fine. However it was a really bad line and I was on the school run and couldn't hear very well. She said she'd ordered an extra test something for the liver and it was mildly elevated and he may be low in vit D and his liver is stealing calcium from his bones? What test would that be, anyone? Is it a concern?