There isn't a need to memorize all lab values, but the most commonly tested ones are worthwhile. This includes:
Sodium: 136-145
Potassium: 3.5 - 5
Calcium: ~9-11
Fasting blood glucose: 70-110
Hemoglobin: 14 - 18 (or 12 - 16 for females) -Hematocrit is basically 3x Hb.
MCV: 80-100
WBC: ~5,000-10,000
ALT 10-40
AST: 10-60
The rest are less common and you can always refer to the normal lab values during the exam.
As far as second guessing, you can mark a question as "guessed" while you do practice questions and see how you're doing when you're guessing compared to your regular average. There is also the ChoiceTrax statistics to see how often you're changing your answers from right to wrong, and vice versa. Be sure to pay attention to these two metrics and see if you should stick to what you're doing or change your strategy. If you're really 50/50 on the actual exam, just choose one of the two, flag the question, and review it if time permits. Don't get bogged down on a question - it's a waste of time in the grand scheme of things (remember each question is 0.0025 of the exam and you're much better off guessing and moving onto questions that are testing topics that you know better). As far as time management goes, check how much time you're spending compared to how much time your peers are spending for each question. As long as you're around the average, you should be fine. We are actually updating all of the Level 2-CE questions this year and early next year now that Level 1 revamp is about to be wrapped up so that the questions are longer since the COMLEX is changing. The practice COMAT questions are written with the longer stems. But, for now, if you are doing the above you should be okay. As far as sitting through a 400 question exam - this is mental stamina you need to build up through timed, random exams. If you were able to do it for Level 1, this shouldn't be different. Mods: hope this is okay but if you need us to edit anything, please send a PM.
