What lab monitoring do you perform for patients taking isotretinoin?

I am a lab minimalist. I do ALT(past months have eliminated the AST) and fasting TGs at the start. Then at month 2 or max dose 1 mg/kg, I check ALT and fasting TGs. If there are any elevations at baseline, will check at month one which is usually 0.5mg/kg for me, and then month 2 (at the max dose) and if everything is STABLE then I will give a lab holiday and check in 2-3 months as long as I know the symptoms: abdominal pain and muscle pain (excessive).

If I am starting a low dose and baseline labs are normal, (I often start 10mg in a certain phenotype to avoid a fulminans flare), I will not check until I am at the 1 mg/kg, even if this is month 4-5.

If someone is reporting excessive nose bleeds, bad abdominal pain, or severe muscle pain ...

I echo Dr. @Dr. First Last's statements and rationale above. I routinely check only ALT and triglycerides at baseline (within a month prior to initiation), and then again at the goal dose of 1 mg/kg/day. This, of course, is modified by patient-specific factors--mainly any abnormalities at baseline--as well as the occasional parent who is more comfortable with monthly checks while their child is on the medication (I've had a few that insist on doing so, despite good evidence to refute routine checks in otherwise asymptomatic patients). I find that the decreased number of lab draws is appealing to many patients who might not otherwise take the medicine were it to require monthly checks throughout the course of therapy.

The labs done for isotr...