Effect of narrowband ultraviolet B phototherapy on serum folic acid levels in patients with psoriasis

Abstract

Narrowband ultraviolet B phototherapy (NB-UVB) is a widely used modality in the treatment of psoriasis and is generally accepted as safe in pregnancy. Previous studies have described photodegradation of serum folate after exposure to UVA radiation but the effect of UVB is not known. We studied the effect of NB-UVB phototherapy on serum folic acid levels in patients with psoriasis and the relationship between changes in serum folate levels and the total cumulative dose of NB-UVB. Included in the study were 30 psoriatic patients between 13 and 55 years of age. Serum folate levels were measured at baseline, and after exposure to 18 and 36 sessions of NB-UVB irradiation. There were significant decreases in mean serum folate levels after NB-UVB exposure. After exposure to 18 and 36 sessions the decreases were 19% and 27%, respectively. After 18 sessions, the mean serum folate level had decreased in 18 patients (60%) from 8.64 ng/ml at baseline to 7.02 ng/ml (mean NB-UVB cumulative dose 40.02 J/cm(2); P = 0.019). After 36 sessions, the mean serum folate levels had decreased in 22 patients (73%) to 6.32 ng/ml (mean NB-UVB cumulative dose 118.16 J/cm(2); P = 0.002). The present study showed that high cumulative NB-UVB doses can induce folate photodegradation and decrease serum folate levels in patients with psoriasis and that this effect is directly related to the total cumulative dose of NB-UVB.

Cases of psoriasis improved by lowering homocysteine using 4-7 mg folic acid, vitamins B6 and B12 previously worsened using 1-2 mg daily folic acid, B6 and B12 folic acid

“…With a possible mean loss in folate levels of up to 27% while Patient 3 was on nb-UVB over 18 treatments [38], This patient's psoriasis flared on 1 mg daily folic acid but cleared slightly when given 4 mg a day.…”

Acneiform Eruptions and Pregnancy

“…The data regarding the safety of NBUVB treatment in pregnant women comes from its use in pregnant psoriasis patients. But recently it has been shown that patients with high cumulative NBUVB doses have a decrease in serum folic acid levels [49]. This finding is especially important for the pregnant women as they usually need folic acid supplementation to prevent neural tube defects.…”

Gravidez, Aleitamento e Fármacos em Dermatologia: Tratamento Tópico

“…71 Apesar disso, os níveis séricos maternos de ácido fólico podem sofrer redução com altas doses cumulativas de fototerapia UVB. [72][73][74] Por sua vez, a deficiência de ácido fólico no primeiro trimestre pode predispor ao desenvolvimento de defeitos do tubo neural. 72,74 Assim, as doentes grávidas que recebam tratamentos de fototerapia UVB devem ser submetidas ao doseamento regular dos níveis de ácido fólico, especialmente durante o primeiro trimestre da gravidez.…”

“…[72][73][74] Por sua vez, a deficiência de ácido fólico no primeiro trimestre pode predispor ao desenvolvimento de defeitos do tubo neural. 72,74 Assim, as doentes grávidas que recebam tratamentos de fototerapia UVB devem ser submetidas ao doseamento regular dos níveis de ácido fólico, especialmente durante o primeiro trimestre da gravidez. 73 É importante saber que o aumento da temperatura corporal central da grávida durante o primeiro mês da gestação pode aumentar o risco de defeitos do tubo neural fetais.…”