Yes, TETANY is a Scrabble word!

Letter values in Scrabble US: T 1, E 1, T 1, A 1, N 1, Y 4.

Is it a valid word?

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

clinical neurological syndrome characterized by muscular twitching and cramps and (when severe) seizures; associated with calcium deficiency (hypoparathyroidism) or vitamin D deficiency or alkalosis

Also: intermittent tetanus, intermittent cramp, apyretic tetanus.

Not playable in Scrabble US: TETANILLA.