How to Determine the input and output values of stored procedures?
You should be able to do that using the system view INFORMATION_SCHEMA.PARAMETERS.
You'll have there what you need.

It "returns one row for each parameter of a user-defined function or stored procedure that can be accessed by the current user in the current database. For functions, this view also returns one row with return value information."

PS: if the answer to Martin's question is "columns in the result set", then ignore my answer, it is only for the parameters of the procedures, not for any result.