My daughter had low platelet count while trying out Pentasa. Unfortunately, at the same time she was trying out Pentasa she developed mononucleosis, so the docs didn't know whether it was the Pentasa or the mono that was causing the lab result. She went off Pentasa just in case it was.
Right now she is trying Pentasa again. She hasn't had any labs done, yet, to see how she is doing on it.