Henna: a potential cause of oxidative hemolysis and neonatal hyperbilirubinemia.

OBJECTIVE To evaluate the in vitro oxidation potential of lawsone (2-hydroxy-1,4 naphthoquinone). Lawsone is a chemical present in henna, the crushed leaves of which are used worldwide as a cosmetic agent to stain the hair, skin, and nails. METHODOLOGY Venous blood from glucose-6-phosphate dehydrogenase (G6PD)-normal and G6PD A- subjects were incubated with various amounts of lawsone for 2 hours at 37 degrees C. Reduced glutathione and methemoglobin (MHb) levels were measured before and after incubation. RESULTS Final molar concentrations of lawsone in normal blood of 1.4, 2.8, 5.7, and 8.6 x 10-3 mol/L increased MHb percentages from 0.5% to 2.2%, 8.3%, 9.5% and 12.5%, respectively. In a C6PD A- blood, MHb percentages were 19.8%, 32.2%, 44.9%, and 53.9%. At a lawsone concentration of 2.8 x 10-3 mol/L, blood from 15 healthy adults formed MHb percentages of 7.4% +/- 3.3% (+/- 1 SD); in blood from 4 G6PD A- adults, percentages were 44.5%, 40.6%, 41.3%, and 42.8%. Simultaneous measurements of reduced glutathione revealed preincubation values of greater than 40 mg/100 mL of red cells in blood of healthy and G6PD A- subjects. Postincubation values were greater than 40 in blood of healthy subjects and less than 40 in blood of G6PD A- subjects. CONCLUSIONS These in vitro observations indicate that lawsone is an agent capable of causing oxidative hemolysis. In regions of the world where there is a high incidence of G6PD deficiency and unexplained hyperbilirubinemia, oxidative hemolysis secondary to the cutaneous application of henna could be the initiating event.