Isotretinoin Lab monitoring: What makes sense to check .. and when?

Checking ALT and Triglycerides makes the Most Sense in Isotretinoin Users

Isotretinoin is famously used for treating acne and first came to market in 1982. The drug is also used by hair loss specialists for the management of several conditions including frontal fibrosing alopecia, dissecting cellulitis, folliculitis decalvans and rarely lichen planopilaris too.

It’s critically important for hair specialists to know what blood tests to perform before a patient starts therapy with isotretinoin and then what tests to perform in follow up. Ordering every test in the books makes little sense but on the flip side, failing to order the right test and the right time could have serious consequences.

The original drug monograph recommended frequent monitoring of lipids and liver function tests at weekly or biweekly intervals. However, recent data suggested that there may be little evidence supporting frequent routine monitoring. Even if an abnormality is found, it tends to be mild and often short term and does not affect the treatment plan.

Xia et al, 2022

I was interested to read a study of acne experts and their views on lab testing in patients with acne. The study design was a Delphi type study in four rounds. Consensus was set at 70 %.

There were 22 participants. All in all, acne experts agreed that the following are important (ie consenus was achieved in the Delphi process)

a) check alanine aminotransferase within a month prior to initiation (89.5%) and at peak dose (89.5%) but not monthly (76.2%) or after stopping treatment (73.7%);

b) check triglycerides within a month prior to initiation (89.5%) and at peak dose (78.9%) but not monthly (84.2%) or after stopping treatment (73.7%);

c) do not check complete blood cell count or basic metabolic panel parameters at any point during isotretinoin treatment (all >70%);

d) do not check GGT liver enzymes (78.9%), bilirubin (81.0%), albumin (72.7%), total protein (72.7%), low-density lipoprotein (73.7%), high-density lipoprotein (73.7%), or C-reactive protein (77.3%).

Summary of Results

Conclusion

This study highlights the simplicity of lab testing for most patients on isotretinoin. Long lists of tests are not needed for most patients but nevertheless this does need to be taken on a case by case basis. ALT and triglycerides are the key tests and these can be done before starting and then again around 2 months in most hair loss patients at the doses we use in hair loss. Repeat testing on a monthly basis is not needed unless there is some clinical suspicion that something is not quite right. An example of this would be ordering a CK in a patient with muscle pain.

REFERENCE

Xia E et al. Isotretinoin Laboratory Monitoring in Acne Treatment: A Delphi Consensus Study. JAMA Dermatol. 2022 Jun 15.