Firstly, if you now decide to use 7 fields for your tests, what happens if a patient comes the 8th time?
Secondly, you have to programm all the logic to show and hide the test-fields needed or not needed.
Third, what if you want to check which test was done by which patient? Your have to code complex where-statement, combining WHERE's for all your test-fields.
And lastly, it simply a bad design to store data in anon-normalized way. Whats wrong with the already offered solutions?