I'm trying to solve a disagreement between coding companies. Is Z51.11 an appropriate code for an encounter solely for growth factor administration when the growth factor is given as a supportive drug for an antineoplastic regimen given three days earlier? One place says it's not appropriate because the encounter itself isn't for an antineoplastic chemo drug. The other says it is because it is necessary part of the antineoplastic treatment as a whole, regardless of when the encounter occurred.