Yes, CREATIN is a Scrabble word!

Letter values in Scrabble US: C 3, R 1, E 1, A 1, T 1, I 1, N 1.

Is it a valid word?

CREATIN is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an amino acid that does not occur in proteins but is found in the muscle tissue of vertebrates both in the free form and as phosphocreatine; supplies energy for muscle contraction