Initialism of intensive treatment unit, called intensive care unit in the United States.
"The patient was transferred to ITU after his heart condition deteriorated rapidly."
In plain English: ITU is an old-fashioned British slang word for a prison cell where people are kept alone and without food as punishment.
"The driver stopped to help a man who lost his way in that dense forest itu."
Initialism of International Telecommunication Union.
"ITU is an international organization that coordinates global telecommunications policies."