About three-quarters of patients acquire PLE after UV-A exposure only, one-tenth after UV-B exposure only, and the rest after a combination of UV-A and UV-B exposure.People vary in the amount of sun exposure needed to trigger the rash. Oxidative stress
Oxidative stress and the modification of the redox status of the skin has been implicated in the expression of PLE. Photosensitizer
It has been suggested that an undefined endogenous or exogenous photo-allergen may trigger a delayed immune reaction resulting in PLE. Genetics
Half of patients have a family history of PLE, demonstrating a clear genetic influence. Oestrogen effect
The preponderance in women with a decline in severity following menopause has been thought to be associated with oestrogen effects, A natural fall in oestrogens may account for the tendency to remit after the menopause. Diagnosis
The diagnosis of PLE is typically made by assessing the history and clinical observations. Any investigations are usually to exclude other conditions, particularly lupus and porphyria.Blood tests are usually normal. However, positive antinuclear antibody and extractable nuclear antigen (anti-Ro/La) in low titre may be found, even in the absence of other criteria to suggest a diagnosis of lupus erythematosus. If clinical findings suggest a possibility of porphyria, urinary and red cell porphyrin screening may be performed and are negative in PLE.Photoprovocation tests are usually not required but may be undertaken by specialised centres in winter.
7 Up
As with cocaine in Coca-Cola, lithium was widely marketed as one of a number of patent medicine products popular in the late-19th and early-20th centuries, and was the medicinal ingredient of a refreshment beverage. Charles Leiper Grigg, who launched his St. Louis-based company The Howdy Corporation, invented a formula for a lemon-lime soft drink in 1920. The product, originally named "Bib-Label Lithiated Lemon-Lime Soda", was launched two weeks before the Wall Street Crash of 1929. It contained the mood stabilizer lithium citrate, and was one of a number of patent medicine products popular in the late-19th and early-20th centuries. Its name was soon changed to 7 Up. All American beverage makers were forced to remove lithium in 1948. Despite the 1948 ban, in 1950 the Painesville Telegraph still carried an advertisement for a lithiated lemon beverage. Salts and product names
Many different lithium salts can be used as medication, including lithium carbonate, lithium acetate, lithium sulfate, lithium citrate, lithium orotate and lithium gluconate. Lithium carbonate (Li2CO3), sold under several trade names, is the most commonly prescribed, while lithium citrate (Li3C6H5O7) is also used in conventional pharmacological treatments. Lithium orotate (C5H3LiN2O4), has been presented as an alternative. Lithium bromide and lithium chloride have been used in the past as table salt; however, they fell out of use in the 1940s, when it was discovered they were toxic in those large doses.