Is there a way to determine if a parameter in a stored proc has a default value (and thus not required) in code - .Net?

I am already pulling the parameters from the stored proc sent in like this:

 foreach (SqlParameter param in cmd.Parameters)
            {
               if ((param.Direction == ParameterDirection.Input) || (param.Direction == ParameterDirection.InputOutput))
                {
                    jsonReturn += "{\"paramName\":\"" + param.ParameterName + "\", \"paramType\":\"" + param.SqlDbType.ToString() + "\"},";
                }
            }

I looked into the SqlParameter object and could not find a way to see if it could tell me whether the Parameter had a default value... (although my debugger is acting weird, so who knows).

What I am doing is building a sort of Stored Proc helper for users.. I currently tell them all the parameters that belong to the Stored Proc they pick.... I WOULD REALLY like to be able to tell whether they are required.