Multiline And Changing Text Box Size?

I have some text pulled in from a db via cfm and remoted into flash - I'm trying to figure out a way to determine if whether or not a given string requires the vertical space of a multiline text box.Visually, two lines take up more space than a single line and when the string only takes up a single line, the second (empty) line creates to much whitespace and has everything below it too far away from that initial single line. When the string can fill both lines, it doesn't look bad at all - so, ultimately, I'm trying to get that whitespace gone.