Hi,
To give a decent answer we need to know the accuracy and resolution you need, or if you are not sure, what are you using it for? An idea of your programming expertise and language used would be useful too.
I'm sorry to be pedantic but the reason for industrial current loop signals ranging between 4 and 20mA is not because it's hard to get a zero current. The 4mA minimum is because the remote sensor is (optionally) powered by the signalling (4-20mA) current. The the minimum was zero there would be no power to operate the sensor.