Yes, OLIGURIA is a Scrabble word!

Letter values in Scrabble US: O 1, L 1, I 1, G 2, U 1, R 1, I 1, A 1.

Is it a valid word?

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

abnormally small production of urine; can be a symptom of kidney disease or obstruction of the urinary tract or edema or an imbalance of fluids and electrolytes in the body
production of an abnormally small amount of urine