Laboratory Monitoring in Isotretinoin Therapy for Acne: How Long and How Often Must We Test Our Patients?

The optimal frequency and timing of laboratory monitoring during isotretinoin treatment remains controversial. We aimed to investigate the frequency, timing, and severity of abnormal results during isotretinoin for acne. We conducted a retrospective cohort study comprising 444 acne patients prescribed isotretinoin at Boston Medical Center from 2004 to 2017; these patients had at least one available baseline laboratory result. We categorized patients into two groups: group A (normal values at baseline and during the first 2 months of isotretinoin therapy) and group B (abnormal values at baseline or during the first 2 months of isotretinoin therapy) and assessed the laboratory values after 2 months. The frequency of abnormal results for triglycerides, cholesterol, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) after 2 months for patients in group A was 21.1%, 13.6%, 8.8%, and 6.0%, respectively, with very rare grade 2 (moderate) or higher abnormalities. In contrast, the frequency of abnormal results for patients in group B for triglycerides, cholesterol, AST, and ALT was higher at 67.9%, 88.0%, 40.0%, and 25.0%, respectively (P < 0.05, except for ALT). No patient developed higher than grade 1 (mild) complete blood count (CBC) abnormality. This study proposed that healthy patients with normal results at baseline and during the first 2 months of isotretinoin therapy might not need routine monitoring after month 2 of medication. Routine monitoring of CBC is not necessary.