Vitamin D deficiency can sometimes be inferred by Autofluorescence of skin - 2015

Skin which is illuminated at one wavelength is found to give off light at other wavelengths. The amount and color of light emitted appears to be associated with the degree of vitamin D deficiency in various diseases

• Autofluorescence Wikipedia
  • Autofluorescence is the natural emission of light by biological structures such as mitochondria and lysosomes when they have absorbed light
  • The autofluorescence of human skin can be used to measure the level of advanced glycation end-products (AGEs), which are present in higher quantities during several human diseases.
• Live tissue intrinsic emission microscopy using multiphoton-excited native fluorescence and second harmonic generation
  • 2003 – Cholecalciferol. Referenced in Wikipedia
  • 📄 Download the PDF from VitaminDWiki

• Vitamin D status is associated with skin autofluorescence in patients with type 2 diabetes mellitus: a preliminary report
  • July 2015, Free PDF online

• Is Vitamin D Deficiency Related to Accumulation of Advanced Glycation End Products, Markers of Inflammation, and Oxidative Stress in Diabetic Subjects? early 2015
  • 📄 Download the PDF from VitaminDWiki

• SUN-LB006: Skin Autofluorescence is a Determinant for Vitamin D in Women with COPD
  • ESPEN Conference Sept 2015, abstract is behind $36 paywall
  • ESPEN = European Society for Clinical Nutrition and Metabolism