foreach (FamilyParameter familyParam in familyDoc.FamilyManager.Parameters)
{
    string familyParamName = familyParam.Definition.Name;
    try
    {
        Guid guid = familyParam.GUID;
        TaskDialog.Show("Revit",familyParamName + " is shared. Guid is " + guid);
    }
    catch (System.Exception)
    {
        TaskDialog.Show("Revit",familyParamName + " is NOT shared");
    }
}

For Each familyParam As FamilyParameter In familyDoc.FamilyManager.Parameters
    Dim familyParamName As String = familyParam.Definition.Name
    Try
        Dim guid As Guid = familyParam.GUID
        TaskDialog.Show("Revit", familyParamName & " is shared. Guid is " & Convert.ToString(guid))
    Catch generatedExceptionName As System.Exception
        TaskDialog.Show("Revit", familyParamName & " is NOT shared")
    End Try