We do heel prick tests, dropping two spots of blood onto special cards. This is done 4 times a day for 2 days (before am dose, lunchtime, before pm dose, and middle of the night). This allows a profile of how the levels vary through the day and gives a better idea of how well the level is suppressed, and also whether the large dose should be AM or PM or spread in 3 lots through the day. We do this at home and post the cards off, it's more accurate than one test and less stressful for my son as he is not in hospital.