PDT
Abbreviation with 3 meanings
| Stands for | Pacific Daylight Time |
|---|---|
| Meanings | 3 |
| Categories | Units & Measurements, Medical, Business & Finance |
PDT has three meanings. The most common are Pacific Daylight Time (time zone) and Photodynamic therapy (dermatology); it can also stand for Pattern day trader.
Meanings of PDT at a glance
| # | PDT stands for | Context |
|---|---|---|
| 1 | Pacific Daylight Time | Units & Measurements › Time Zone |
| 2 | Photodynamic therapy | Medical › Dermatology |
| 3 | Pattern day trader | Business & Finance › Stock Market & Investing |
1. Pacific Daylight Time
Units & Measurements · Time Zone Abbreviations
Seven hours behind UTC, PDT is the warm-season clock of the US West Coast and British Columbia, observed from the second Sunday in March to the first Sunday in November. Product launches, game updates and West Coast sports broadcasts quote it in summer.
Example: The update rolls out at 9 a.m. PDT (16:00 UTC) on Tuesday.
PDT has the same offset as Mountain Standard Time, so in summer Los Angeles and Phoenix show identical clock times. British Columbia passed legislation in 2019 to adopt permanent daylight time, conditional on neighboring US states doing the same.
2. Photodynamic therapy
Medical · Dermatology Abbreviations
Treatment that applies a light-sensitizing drug such as aminolevulinic acid to the skin and then activates it with blue or red light, destroying abnormal cells. It is used mainly for actinic keratoses and, in some countries, superficial basal cell carcinoma and acne.
Example: Blue-light PDT to face for 15 AKs; strict sun avoidance for 48 hours.
Treatment can sting or burn during illumination, and the skin stays light-sensitive for about two days. "Daylight PDT", using natural light, is less painful and popular in Europe. Cosmetic results are often better than with cryotherapy or surgery. The same principle is used in some cancer and eye treatments.
3. Pattern day trader
Business & Finance · Stock Market & Investing Abbreviations
FINRA designation for a margin-account customer who makes four or more day trades within five business days, provided they exceed 6 percent of the account's trades in that period. Pattern day traders must keep at least $25,000 of equity in the account.
Example: After a fourth round-trip trade this week, her account was flagged as PDT and restricted.
The rule, part of FINRA Rule 4210, dates from 2001, after the dot-com boom in online day trading. Accounts below $25,000 cannot day trade until equity is restored. The rule applies to margin accounts; cash accounts avoid it but must trade only with settled funds.
Related abbreviations
More time zone abbreviations
- NPT – Nepal Time
- NST – Newfoundland Standard Time
- NZDT – New Zealand Daylight Time
- NZST – New Zealand Standard Time
- PKT – Pakistan Standard Time
- PST – Pacific Standard Time
- PT – Pacific Time
- SAST – South African Standard Time
See all 64 time zone abbreviations →
More dermatology abbreviations
- MMS – Mohs micrographic surgery
- NB-UVB – Narrowband ultraviolet B phototherapy
- NMSC – Nonmelanoma skin cancer
- PASI – Psoriasis Area and Severity Index
- PIH – Post-inflammatory hyperpigmentation
- PR – Pityriasis rosea
- PsO – Psoriasis
- PUVA – Psoralen plus ultraviolet A
See all 52 dermatology abbreviations →
This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.