Isotretinoin modestly increases platelet count in acne patients

Isotretinoin (ISO) has been used over 25 years for the treatment of severe acne, and it affects nearly all the etiopathogenetic aspects of this disease (1,2). ISO side effects involve several organ systems, most commonly mucocutaneous, and can cause dyslipidemia and liver enzyme elevation (1,3). Thrombocytopenia, agranulocytosis and leukopenia have been associated with ISO in several case reports (3), but a previous study found that no abnormalities were found in hemoglobin, white blood cell and platelet counts and the researchers suggested not to measure these parameters in patients treated with ISO (4). In this study, we aimed to investigate the possible effect of ISO on blood cell counts.

Seventy patients with moderate to severe nodulocystic acne, who had therapeutic failure with topical remedies and tetracyclines (47 females, 23 males, age: 21.5 ± 4.8 years) from November 2010 to June 2011, were included. ISO therapy was initiated at a dose of 0.5–0.75 mg/kg body weight. The drug was administered twice daily with a meal for at least 5 months. Screening for complete blood count was done just before initiation and after 3 months of ISO treatment. Complete blood count was performed by an automated COULTER^® LH 780 Hematology Analyzer (Beckman Coulter, Inc., Miami, FL, USA). A Wilcoxon signed-rank test was used for analysis of data with skew variability; significance was defined as p < 0.05. Platelet counts 3 months into treatment (274.4 ± 62.8) were higher than baseline counts (252.4 ± 59, p < 0.0001). Posttreatment hemoglobin, hematocrit and white blood cell counts did not change (Table I).

Table I. The pretreatment and posttreatment results of all the blood count findings.

	Pretreatment mean ± SD	Posttreatment mean ± SD	p Value
Hemoglobin (g/dl)	16.17 ± 14.0	15.95 ± 13.0	0.162
Hematocrit (%)	47.63 ± 5.2	41.34 ± 6.8	0.311
MPV	8.42 ± 0.8	8.38 ± 0.9	0.582
White blood count (/ml)	7.29 ± 1.6	7.12 ± 1.6	0.385
Platelet (K/mm^3)	252.44 ± 59.8	274.43 ± 62.8	<0.0001

MPV = mean platelet volume; SD = standard deviation.

We found a modest rise in platelet count associated with ISO treatment. Several studies with other retinoids investigated platelet counts before and after treatment. All-trans retinoic acid (ATRA) stimulates megakaryopoiesis of progenitor cell line MEG-01 cells (5). The resulting megakaryocytes stayed viable for more than 3 weeks. Retinoic acid enhances the generation of hematopoietic progenitors from human embryonic stem cell-derived hemato-vascular precursors (6). ATRA in patients with myelodysplastic syndrome increased both absolute neutrophil counts and platelet counts in 3 out of 15 patients (7). In a Phase I clinical trial of 13-cis-retinoic acid (13-cRA) in patients with myelodysplastic syndromes, 5 out of 15 patients showed an increase in platelet counts (8). This effect does not appear to be of clinical importance in acne patients and our findings confirm that following blood counts is not necessary during ISO treatment of acne.