UV Light Therapy

UV light therapy (light therapy with ultraviolet light) is not only used in the treatment of dermatological diseases (see: UVB 311 nm light therapy; light therapy for psoriasis). This article discusses the effect of UV radiation on vitamin D3 balance and the resulting therapeutic use.

Indications (areas of application)

  • Rickets – This disease occurs in childhood and is due to insufficient calcium or phosphate, this is usually caused by vitamin D deficiency. For this reason, the mineralization of growing bones is disturbed and skeletal changes occur.
  • Osteomalacia – This disease occurs in adulthood and corresponds to rickets.
  • Generalized tendoperiostoses – spindle-like widening of the periosteum (periosteum) in the area of tendon insertions.
  • Vitamin D deficiency diseases

The procedure

UV light is the invisible, higher-energy radiation that joins the violet of visible, natural light in the light spectrum. The spectrum of UV radiation is divided as follows:

  • UV-A radiation (UVA1 – 320-340 nm; UVA2 – 340-400 nm) – so-called tanning radiation.
  • UV-B radiation (280-320 nm) – This UV radiation stimulates melanocytes (cells that produce brown skin pigment), produces inflammatory erythema (redness) and is significantly involved in the synthesis or activation of vitamin D3 (cholecalciferol). Vitamin D3 is an essential factor of mineral balance, regulating calcium concentration in the blood and participating in enchondral ossification (ossification). This is also where the therapeutic importance of this UV light therapy lies. Cholecalciferol must be activated from cholesterol under the influence of UV-B radiation, which is also contained in sunlight. If the oral administration of cholecalciferol is not possible, then the increased formation from endogenous cholesterol can be stimulated by UV light therapy.
  • UV-C radiation (200-280 nm) – This UV radiation also causes erythema, affects the bacterial flora of the skin and can cause light conjunctivitis (conjunctivitis caused by light).

To ensure safe use of UV light therapy is first determined the so-called MED (minimum erythema dose). For this purpose, sensitive, usually light-protected skin (eg on the forearm) is illuminated with different radiation intensities. After 24 hours, the erythema formation (redness) is subsequently assessed and the therapy is individually adjusted.

Benefits

UV light therapy is also used, among other things, for diseases caused by vitamin D deficiency. Especially in patients for whom oral intake of cholecalciferol is not possible (e.g., bedridden patients who cannot receive enteral nutrition), this therapy can be of great benefit.