Minimal erythema dose (UVB and UVA) and minimal phototoxic dose (PUVA), which represent the lowest dose that produces erythema (sunburn reaction) of the skin. The MED varies depending on skin type.
- UVA: 20 to 40 J/cm2 (maximum erythema noted within 12 hours of treatment)
- BBUVB: 20 to 40 mJ/cm2 (within 24 hours)
- NBUVB: 200 to 400 mJ/cm2 (48 to 72 hours)
- PUVA: 4 to 15 J/cm2 (48 to 72 hours)
- BBUVB is approximately 1000 times more erythemogenic than is UVA. Note that UVA is measured in Joules/cm2 and UVB is measured in mJ/cm2.
The MED/MPD testing is important because it allows the clinician to start phototherapy at a higher dose, achieving quicker responses with fewer treatments.
