Which is more accurate? Urine calcium test or blood test

[Aly2]

Does anyine know which test is more accurate. My calcium urine test came back low via medichecks, but my blood test via my GP came back normal. My GP said to dismiss the urine one from medichecks as the blood test they did is a lot more accurate. Obviously doctor knows best but im wondering why the urine one was abnormal and the blood was not, anyone had conflicting results and have been told a blood test is more accurate? Thanks