I do test blood ketones periodically but I know that as long as I keep my fat intake up with moderate protein and very low carb, I'll stay in ketosis. (taliand.com)
But, keep in mind that very high levels of blood ketones can be indicative of poor keto - adaptation. (ketodietapp.com)
If you're in ketosis, blood ketones read between 0.5 and 5.0, with 1.5 to 3 being the ideal range for fat burning. (drpompa.com)