Name: Minimal Erythema Dose (MED) Testing (Video) | JoVE Journal
Uploaded: 2013-05-28T12:00:00.000+00:00
Duration: 6 min 24 s
Description: Learn minimal erythema dose testing for dermatology using UV exposure protocols. This method helps researchers assess individual skin sensitivity and establish safety guidelines for radiation exposure.

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5 minutes

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.

1. Preparing for UV Exposure
	<ol>
		<li>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.")</li>
	 <li>Staff and participant should wear UV protective glasses.</li>
	 <li>The participant should be wearing a short-sleeved shirt or roll her sleeve up.</li>
	 <li>Have the participant put on a glove to protect the skin on her hand. </li>
	 <li>Remove the Daavlin patch1 backing on the left and right sides of the patch, and place it on the inner lower arm just adjacent to the glove, avoiding any existing skin blemishes.</li>
		<li>Cover any additional skin on the arm with the participant's shirt or other material.</li>
	 <li>Place the arm so that the holes in the patch will be exposed to the UV light source. No other skin should be exposed to the UV light.</li>
	 <li>Tell the participant she will feel warmth but her arm will not be burning during the test.</li>
	</ol>
	2. Conducting UV Exposure
	<ol>
		<li>Patch holes (e.g. 6) should be exposed to UV at intervals throughout the exposure period. </li>
	 <li>Start with hole 1 open.</li>
	 <li>Select the total duration of the exposure based on the manufacturer specifications for the light source and the participant's Fitzpatrick skin type I-VI (very fair to very dark; Fitzpatrick, 1988).2 Fairer skin is more likely to burn.</li>
	 <li>Set a timer for the total duration of exposure (e.g. 20 min). A second backup timer may also be used. Start the timer(s). </li>
	 <li>For example, open hole 2 after 2 min, open hole 3 after 4 min, open hole 4 after 8 min, open hole 5 after 12 min, and open hole 6 after 16 min. Thus, the skin UV exposure times will be 20 min for hole 1, 18 min for hole 2, 16 min for hole 3, 12 min for hole 4, 8 min for hole 5, and 4 min for hole 6.</li>
	 <li>In order to more easily identify the exposed areas after 24-48 hr, mark the skin exposed on the far edge of the first and last holes of the patch and ask the participant to not wash off the marks until after the skin is examined.</li>
	 <li>Have the participant remove the glove and patch.</li>
	 <li>Reiterate to the participant that the skin must be reexamined in 24-48 hr.</li>
	</ol>
	3. Assessing the MED
	<ol>
		<li>After 24-48 hr, examine the exposed areas of skin. Red or pink skin indicates erythema or burning. Erythemetous skin exposed to the shortest duration of UV is defined as the minimal erythema dose or MED.</li>
	 <li>Future exposures to UV should be for durations shorter than the MED to avoid burning.</li>
	 <li>If the areas of exposure are difficult to identify, you may want to put the patch back on using the marks to align with the exposed skin. This is also helpful if using a skin color measurement device such as a spectrophotometer. </li>
	 <li>Spectrophotometers provide measures of L* (darkness) and b* (hue). a* refers to the redness of the skin. A higher a* value indicates redder skin.</li>
	 <li>If using a skin color measurement device such as a spectrophotometer, place the spectrophotometer aperture in the center of the hole to be measured. </li>
	 <li>Measure each of the 6 exposure areas in numerical order and one unexposed area near the others for comparison. Try to measure the center of each hole but not a freckle or mole or other non-UV discolorations. Label each of the measurements. The measurement from the unexposed area should be labeled 0 min and be listed next to area 6 (the shortest exposure area - 4 min).</li>
	 <li>Increases in a* values should correspond with increases in UV exposure duration. Try re-measuring values that are not in corresponding order.</li>
	 <li>A 2.5 point difference in the a* of unexposed skin compared to exposed skin indicates a significant difference in redness, suggesting potential burning.</li>
	 <li>Add 2.5 to the lowest a* value. Anything at or above this value would be considered potentially burning. The lowest exposure time above this value is considered the MED.</li>
	</ol>

<ol><li>UV Therapy Accessories | Daavlin [Internet]. , The Daavlin Company. Available from: 
 <a target="_blank" href="http://www.daavlin.com/patients/phototherapy-products/uv-therapy-accessories/">http://www.daavlin.com/patients/phototherapy-products/uv-therapy-accessories/</a> (2012).</li>
<li>Fitzpatrick, T. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+validity+and+practicality+of+sun-reactive+skin+types+I+through+VI%5BTitle%5D)+AND+%22Archives+of+Dermatology%22%5BJournal%5D)">The validity and practicality of sun-reactive skin types I through VI.</a> Archives of Dermatology. 124, 869-871 (1988).</li>
<li>SPF Testing 601 Multiport UV Solar Simulator | Solar Light - Solar Light [Internet]. , Solar Light Company, Inc.. Available from: 
 <a target="_blank" href="http://solarlight.com/product/model-601-multiport-spf-testing-6-output-solar-simulator/">http://solarlight.com/product/model-601-multiport-spf-testing-6-output-solar-simulator/</a> (2012).</li>
<li>eCFR - Code of Federal Regulations [Internet]. , U.S. Government Printing Office. Available from: 
 <a target="_blank" href="http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?type=simple;c=ecfr;cc=ecfr;idno=21;region=DIV1;q1=201;rgn=div2;sid=2e707692c7adf31cc3772389d813a3bb;view=text;node=20110617%3A1.33;start=1;size=25">http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?type=simple;c=ecfr;cc=ecfr;idno=21;region=DIV1;q1=201;rgn=div2;sid=2e707692c7adf31cc3772389d813a3bb;view=text;node=20110617%3A1.33;start=1;size=25</a> (2012).</li>
<li>Bodekaer, M., Akerstrom, U., Wulf, H. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Accumulation+of+sunscreen+in+human+skin+after+daily+applications%3A+a+study+of+sunscreens+with+different+ultraviolet+radiation+filters%5BTitle%5D)+AND+%22Photodermatol.+Photoimmunol.+Photomed%22%5BJournal%5D)">Accumulation of sunscreen in human skin after daily applications: a study of sunscreens with different ultraviolet radiation filters.</a> Photodermatol. Photoimmunol. Photomed. 28, 127-132 (2012).</li>
<li>light, lighting, illumination, lamps, lighting technology, architectural lighting, industrial lighting, LED-lights - Herbert Waldmann GmbH & Co. KG - Test Unit [Internet]. , H. Waldmann GmbH & Co. KG. Available from: 
 <a target="_blank" href="http://www.waldmann.com/waldmann-medizin/home/home/products/therapy_systems_for_professional_use/accessories/test_unit.html">http://www.waldmann.com/waldmann-medizin/home/home/products/therapy_systems_for_professional_use/accessories/test_unit.html</a> (2012).</li>
<li>Kwon, I. H., Kwon, H. H., Na, S. J., Youn, J. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Could+colorimetric+method+replace+the+individual+minimal+erythemal+dose+%28MED%29+measurements+in+determining+the+initial+dose+of+narrow-band+UVB+treatment+for+psoriasis+patients+with+skin+phototype+III-V%3F%5BTitle%5D)+AND+%22J.+Eur.+Acad.+Dermatol.+Venereol%22%5BJournal%5D)">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?</a> J. Eur. Acad. Dermatol. Venereol. , (2012).</li>
<li>Youn, J. I., Park, J. Y., Jo, S. J., Rim, J. H., Choe, Y. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Assessment+of+the+usefulness+of+skin+phototype+and+skin+color+as+the+parameter+of+cutaneous+narrow+band+UVB+sensitivity+in+psoriasis+patients%5BTitle%5D)+AND+%22Photodermatol.+Photoimmunol.+Photomed%22%5BJournal%5D)">Assessment of the usefulness of skin phototype and skin color as the parameter of cutaneous narrow band UVB sensitivity in psoriasis patients.</a> Photodermatol. Photoimmunol. Photomed. 19, 261-264 (2003).</li>
<li>Henriksen, M., Na, R., Agren, M. S., Wulf, H. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Minimal+erythema+dose+after+multiple+UV+exposures+depends+on+pre-exposure+skin+pigmentation%5BTitle%5D)+AND+%22Photodermatol.+Photoimmunol.+Photomed%22%5BJournal%5D)">Minimal erythema dose after multiple UV exposures depends on pre-exposure skin pigmentation.</a> Photodermatol. Photoimmunol. Photomed. 20, 163-169 (2004).</li>
<li>Kraemer, C. K., Menegon, D. B., Cestari, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Determination+of+the+minimal+phototoxic+dose+and+colorimetry+in+psoralen+plus+ultraviolet+A+radiation+therapy%5BTitle%5D)+AND+%22Photodermatol.+Photoimmunol.+Photomed%22%5BJournal%5D)">Determination of the minimal phototoxic dose and colorimetry in psoralen plus ultraviolet A radiation therapy.</a> Photodermatol. Photoimmunol. Photomed. 21, 242-248 (2005).</li>
<li>Sachdeva, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fitzpatrick+skin+typing%3A+applications+in+dermatology%5BTitle%5D)+AND+%22Indian+J.+Dermatol.+Venereol.+Leprol%22%5BJournal%5D)">Fitzpatrick skin typing: applications in dermatology.</a> Indian J. Dermatol. Venereol. Leprol. 75, 93-96 (2009).</li>
<li>Webb, A. R., Kift, R., Berry, J. L., Rhodes, L. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+vitamin+D+debate%3A+translating+controlled+experiments+into+reality+for+human+sun+exposure+times%5BTitle%5D)+AND+%22Photochem.+Photobiol%22%5BJournal%5D)">The vitamin D debate: translating controlled experiments into reality for human sun exposure times.</a> Photochem. Photobiol. 87, 741-745 (2011).</li>
<li>Otman, S. G., Edwards, C., Gambles, B., Anstey, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Validation+of+a+semiautomated+method+of+minimal+erythema+dose+testing+for+narrowband+ultraviolet+B+phototherapy%5BTitle%5D)+AND+%22Br.+J.+Dermatol%22%5BJournal%5D)">Validation of a semiautomated method of minimal erythema dose testing for narrowband ultraviolet B phototherapy.</a> Br. J. Dermatol. 155, 416-421 (2006).</li>
<li>Taylor, D. K., Anstey, A. V., Coleman, A. J., Diffey, B. L., Farr, P. M., Ferguson, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Guidelines+for+dosimetry+and+calibration+in+ultraviolet+radiation+therapy%3A+a+report+of+a+British+Photodermatology+Group+workshop%5BTitle%5D)+AND+%22Br.+J.+Dermatol%22%5BJournal%5D)">Guidelines for dosimetry and calibration in ultraviolet radiation therapy: a report of a British Photodermatology Group workshop.</a> Br. J. Dermatol. 146, 755-763 (2002).</li>
</ol>

We have nothing to disclose.

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 ...

minimal erythema dose (med) testing

Minimal Erythema Dose (MED) Testing

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.

<img alt="UV exposure process diagram; steps: prepare, conduct, assess MED, determine MED; 24-48 hours." fo:content-width="4in" fo:src="/files/ftp_upload/50175/50175fig1highres.jpg" src="/files/ftp_upload/50175/50175fig1.jpg" data-altupdatedat="1787630408000" data-alt="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.
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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 ...

The overall goal of the following experiment is to conduct minimal erythema dose testing in order to determine the lowest dose of ultraviolet radiation that will cause erythema when administered to an individual. This is achieved by first preparing the light source and participant for UV exposure. As a second step, the participant is exposed to UV for varying durations, which may cause erythema, also known as sunburn.Next, changes in skin color are assessed in order to determine the minimal erythema dose results are obtained. The show variation in skin darkening across exposure times of individuals based on visual inspection and spectrometry. My name is Susan Darlow.I'm a postdoctoral fellow in the laboratory of Dr.Carolyn Hackman. Demonstrating the procedure will be Tasia Munchie, a research assistant in Dr.Hackman's lab. I will be demonstrating the research participant role Begin this procedure by explaining to the participant how minimal erythema dose or MED testing works.So I'm going to expose some skin of your skin to your V light for almost 20 minutes and tomorrow we're gonna check the section of the skin to see how sensitive you're to the light. You may experience burn in some parts of that skin, which was exposed to uv, and if it is painful, you can treat like any other sunburns you would have. Once the procedure has been explained, both the staff and participant put on UV protective glasses, then expose the forearm of the participant.Next, remove the dalin patch backing on the left and right sides of the patch and place it on the inner lower arm. Avoid any existing skin blemishes when placing the patch. Have the participant put on a protective glove, cover any additional skin on the arm with the participant's shirt or other material in order to protect those areas from UV exposure.The next step is to position the participant's arm so that the holes in the patch will be in alignment with the UV light source. Double check that no other skin will be exposed to the UV light. Once the participant's arm is in the correct position, inform them that they will feel warmth once the experiment begins, but ensure them that their arm will not be burning during the test.Prior to beginning UV exposure, select the total duration of the exposure based on the manufacturer's specifications for the light source and the participant's Fitzpatrick skin. Type on a scale from one to six on this scale. One represents very fair skin and six represents very dark skin.Then set a timer for the total duration of UV exposure. This participant has a number three skin type, and their exposure time will be 20 minutes. A second backup timer may also be used.Next, remove the covering over hole one on the dalin patch. Turn on the UV light source and start the timer. Uncover subsequent holes on the patch at timed intervals during UV exposure for a 20 minute exposure.Open hole number two after two minutes, hole number three after four minutes. Hole number four after eight minutes. Hole number five after 12 minutes and hole number six, after 16 minutes following UV exposure, mark the scan exposed on the far edge of the first and last holes of the patch with a small dot.In order to more easily identify the exposed areas after 24 to 48 hours, ask the participant to not wash off the marks until after the skin has been examined. Then have the participant remove the glove and patch. Then remind them to return in 24 to 48 hours for the skin to be reexamined.Please be sure to make come back tomorrow so we can test the results. After 24 to 48 hours. Examine the exposed areas of skin.Red or pink skin indicates erythema or burning. Erythema to skin exposed to the shortest duration of UV is defined as the minimal erythema dose or MED placed the patch back on the skin using the small dots in the corners of holes. One in six to position the patch back onto the exposed skin in order to identify the different regions.Once the exposure areas have been identified, place the spectrophotometer aperture in the center of the first hole to be measured. Then measure each of the six exposure areas in numerical order. Next, measure one unexposed area near the others.For comparison, avoid freckles, moles, or other non UV related discolorations. Spectrophotometers provide measures of L star, which represents darkness and B star, which represents hue. A star refers to the redness of the skin.An increase in Astar indicates redder skin and should correspond with increases in UV exposure duration. If astar values do not increase with the increase in UV exposure, duration remeasure the values that are not in corresponding order shown here are typical results seen 24 to 48 hours after UV exposure. The markings left after the experiment assist in aligning the patch, which will be placed back on the arm during spectro photometric measurements of each region.In order to determine the minimal erythema dose spectrophotometer readings are taken and the ASTAR values are calculated for each region, the minimal erythema dose is calculated as being the time of exposure that causes an increase in astar greater than 2.5 above baseline. For this participant, it was 18 minutes of exposure. If the data in the table appears to be out of order, repeat the readings.Taking care not to analyze areas with skin blemishes or areas that are abnormally darkened. In this case, the baseline or NA value is 9.0, but it should be less than that of the four minute duration which read 7.2. After watching this video, you should have a good understanding of how to conduct minimal erything dose testing.

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Learn minimal erythema dose testing for dermatology using UV exposure protocols. This method helps researchers assess individual skin sensitivity and establish safety guidelines for radiation exposure.

Minimal Erythema Dose (MED) Testing

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