Yes that’s an issue for Thriva - IR is an add in option and you do need to sign on for regular tests although you can delay or withdraw but as you only wanted one check the way you chose def is the best. Now I’m so low in IR I’ll probably not Do IR again unless concerned. I do regular basics cholesterol test with Thriva which keep me informed about my progress and ratios and can add in tests of any type eg hbaca1 and may do this next time as will be halfway to next nhs hbaca1 test!
I’m quite interested in checking out vitamins and electrolytes, especially magnesium. This could become another expensive habit!