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Medicine

Minimal Erythema Dose (MED) Testing

Published: May 28th, 2013

DOI:

10.3791/50175

1Cancer Prevention and Control Program, Fox Chase Cancer Center , 2Department of Psychiatry, University of Pennsylvania , 3Department of Psychology, Drexel University , 4Department of Medicine, Fox Chase Cancer Center , 5Cancer Prevention and Control Program, The Cancer Institute of New Jersey

This article describes how to conduct minimal erythema dose (MED) testing in order to determine the lowest dose of ultraviolet radiation that will cause erythema (burning) when administered to an individual.

Ultraviolet radiation (UV) therapy is sometimes used as a treatment for various common skin conditions, including psoriasis, acne, and eczema. The dosage of UV light is prescribed according to an individual's skin sensitivity. Thus, to establish the proper dosage of UV light to administer to a patient, the patient is sometimes screened to determine a minimal erythema dose (MED), which is the amount of UV radiation that will produce minimal erythema (sunburn or redness caused by engorgement of capillaries) of an individual's skin within a few hours following exposure. This article describes how to conduct minimal erythema dose (MED) testing. There is currently no easy way to determine an appropriate UV dose for clinical or research purposes without conducting formal MED testing, requiring observation hours after testing, or informal trial and error testing with the risks of under- or over-dosing. However, some alternative methods are discussed.

1. Preparing for UV Exposure

  1. Explain to the participant how MED testing works ("I'm going to expose some skin on your arm to UV light over the course of about 20 min, and tomorrow, we're going to check that section of your skin in order to determine how sensitive you are to the light. You may experience a sunburn in the small areas that we expose to UV. If the sunburn is painful or bothers you, you can treat it like you would any other sunburn.")
  2. Staff and participant should wear UV prote.......

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Figure 1
Figure 1. The four steps of conducting MED testing: preparing for UV exposure, conducting UV exposure, assessing the MED, and determining the MED.

Figure 2

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Ultraviolet radiation (UV) therapy is sometimes used as a treatment for various common skin conditions, including psoriasis, acne, and eczema. The dosage of UV light is prescribed according to an individual's skin sensitivity, which is determined as a function of the individual's Fitzpatrick skin type I through VI (very fair to very dark).2 Human skin varies in its sensitivity to UV radiation because of varying degrees of skin pigmentation, thickness, and other factors. Thus, to establish the proper dosage of .......

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This work was funded by R21CA134819 (CH), T32CA009035 (SD),and P30CA006927 (Cancer Center Core Grant). The authors would like to thank Elizabeth Culnan for her assistance with participant recruitment, Lia Boyle, Eva Panigrahi, and Kate Menezes for their assistance in the development of procedures, and Jeanne Pomenti with her assistance with manuscript preparation. We also thank the journal reviewers for their helpful suggestions.

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  1. Fitzpatrick, T. B. The validity and practicality of sun-reactive skin types I through VI. Archives of Dermatology. 124, 869-871 (1988).
  2. Bodekaer, M., Akerstrom, U., Wulf, H. C. Accumulation of sunscreen in human skin after daily applications: a study of sunscreens with different ultraviolet radiation filters. Photodermatol. Photoimmunol. Photomed. 28, 127-132 (2012).
  3. Kwon, I. H., Kwon, H. H., Na, S. J., Youn, J. I. Could colorimetric method replace the individual minimal erythemal dose (MED) measurements in determining the initial dose of narrow-band UVB treatment for psoriasis patients with skin phototype III-V?. J. Eur. Acad. Dermatol. Venereol. , (2012).
  4. Youn, J. I., Park, J. Y., Jo, S. J., Rim, J. H., Choe, Y. B. Assessment of the usefulness of skin phototype and skin color as the parameter of cutaneous narrow band UVB sensitivity in psoriasis patients. Photodermatol. Photoimmunol. Photomed. 19, 261-264 (2003).
  5. Henriksen, M., Na, R., Agren, M. S., Wulf, H. C. Minimal erythema dose after multiple UV exposures depends on pre-exposure skin pigmentation. Photodermatol. Photoimmunol. Photomed. 20, 163-169 (2004).
  6. Kraemer, C. K., Menegon, D. B., Cestari, T. F. Determination of the minimal phototoxic dose and colorimetry in psoralen plus ultraviolet A radiation therapy. Photodermatol. Photoimmunol. Photomed. 21, 242-248 (2005).
  7. Sachdeva, S. Fitzpatrick skin typing: applications in dermatology. Indian J. Dermatol. Venereol. Leprol. 75, 93-96 (2009).
  8. Webb, A. R., Kift, R., Berry, J. L., Rhodes, L. E. The vitamin D debate: translating controlled experiments into reality for human sun exposure times. Photochem. Photobiol. 87, 741-745 (2011).
  9. Otman, S. G., Edwards, C., Gambles, B., Anstey, A. V. Validation of a semiautomated method of minimal erythema dose testing for narrowband ultraviolet B phototherapy. Br. J. Dermatol. 155, 416-421 (2006).
  10. Taylor, D. K., Anstey, A. V., Coleman, A. J., Diffey, B. L., Farr, P. M., Ferguson, S., et al. Guidelines for dosimetry and calibration in ultraviolet radiation therapy: a report of a British Photodermatology Group workshop. Br. J. Dermatol. 146, 755-763 (2002).

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