1. Porphyrias British Journal of Anaesthesia
M.F.M. James, R.J. Hift 
British Journal of Anaesthesia 
Volume 85, Issue 1, Pages (July 2000)
DOI: /bja/
Copyright © 2000 British Journal of Anaesthesia Terms and Conditions

2. Fig 1
The structures of the porphyrinogens (left) and porphyrins (right). Substituents are numbered according to the conventional Fisher system. In the porphyrinogen ring, the positions designated by Greek letters are occupied by methyl groups (–CH2), whereas in the porphyrin ring these positions are occupied by methene (–CH=) groups. The colourless porphyrinogens undergo spontaneous conversion to purple-coloured porphyrins on exposure to light and air, hence the characteristic urine colour change, when urinary porphyrinogens are present, from normal to a ‘port wine’ appearance on standing.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2000 British Journal of Anaesthesia Terms and Conditions

3. Fig 2
Metabolic pathways of haem synthesis. The enzymes involved at each step are listed on the left, and the type of porphyria associated with a deficiency of each enzyme is shown on the right. The conditions highlighted in boxes are the acute porphyrias.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2000 British Journal of Anaesthesia Terms and Conditions