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Frequent laboratory monitoring questioned for patients on isotretinoin

MIAMI BEACH, Fla. — Researchers surveyed dermatologists and analyzed results of patients with acne who were treated with isotretinoin and found that frequent laboratory monitoring of the patients may be unnecessary, according to research presented at the American Academy of Dermatology annual meeting.

"Due to the rarity of significant adverse effects with isotretinoin therapy, the utility of frequent laboratory monitoring throughout treatment should be questioned,” researcher Timothy Hansen, MD, a third-year resident in the department of dermatology at Penn State Milton S. Hershey Medical Center, Hershey, Pa., told Healio.com.

 

Timothy Hansen

Lipid and liver monitoring at weekly or biweekly intervals until the response is established has been part of the most recent labeling of isotretinoin, and there is little consensus regarding appropriate frequency and interval of laboratory testing, the study noted.

Researchers conducted a survey of 16 practicing dermatologists from the Penn State Department of Dermatology and identified 515 patients (mean age, 19 years; 313 males) who had been treated with isotretinoin at a regional medical center between May 2003 and July 2011.

Laboratory results were analyzed for serum triglyceride level, alanine aminotransferase, white blood cell count and platelet count. The proportion of patients with abnormalities at baseline or at any time during therapy was used to calculate incidence of laboratory abnormalities.

Of the monitoring practices of the 16 dermatologists, six different frequency patterns were reported, with minimal testing beyond 2 months. Three variations of tests were ordered for liver and lipid profiles +/- complete blood count (CBC). By 30 days into treatment, 9.5% of all abnormalities (95% CI, 5.8%-14.4%) were first detected, and by 60 days into treatment, 67.7% of all abnormalities (95% CI, 60.7% -74.1%). The increase in abnormalities could be explained by a dose escalation of isotretinoin from 0.5 mg/kg/day to 1 mg/kg/day at one month for 64% of patients, the researchers reported.

Leukopenia and thrombocytopenia resolved or remained stable after continued therapy, and there were no patients who developed pancreatitis or persistent liver injury, according to the research results.

“As with other studies, we confirm the clinical insignificances of changes to CBC measurements on isotretinoin,” the researchers concluded. “This test may be eliminated from standard isotretinoin monitoring.

“There was an unexpected finding that most abnormalities are first detected beyond 30 days into isotretinoin therapy. This calls into question the practice of obtaining labs at the first treatment visit given the low yield in detecting abnormal values.”

– Bruce Thiel

For more information:

Hansen T.  P5954 – Standardizing laboratory monitoring of patients undergoing isotretinoin treatment using a cost-effective and best evidence practice. Presented at: American Academy of Dermatology 2013 Annual Meeting; March 1-5, Miami Beach, Fla.