investigations

Last reviewed 01/2018

Investigations include:

  • biochemistry - hyponatraemia, hypomagnesaemia and hypovolaemia may occur during acute attacks
  • definitive test is porphobilinogen deaminase in erythrocytes which is decreased by 50%
  • urine - usually normal colouration when fresh but becomes brown, red or black on standing; marked increase in porphobilinogen (PBG); slightly elevated coproporphyrin and uroporphyrin
  • stool - coproporphyrin and protoporphyrin normal
  • liver function tests - sulfobromophthalein retention
  • increased serum cholesterol, serum iron and T4
  • hyperbetalipoproteinemia
  • abnormal glucose tolerance