Diagnosis Of Porphyria | Pediatric Oncall
PORPHYRIA
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Last Updated : 10/1/2014
Ira Shah
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Diagnosis
Any patient presenting with unexplained abdominal pain, mental dysfunction or peripheral neuropathy should be suspected to have acute porphyria. A clue to the diagnosis is dark reddish brown color of the urine during an attack, which becomes more pronounced if it is left standing. A simple urine test can be done to test for presence of porphobilinogen in the urine. Either 200ml of 24-hour urine is tested (with no added preservative) or spot sample of at least 100ml urine can be tested. Equal volumes of urine and Ehrlich's reagent are mixed in a tube. If solution becomes pink, it indicates either the presence of porphobilinogen or urobilinogen. The presence of porphobilinogen can be confirmed by the addition of about two volumes of chloroform to the solution and completely shaking it. The mixture is allowed to stand. If pink color remains in the upper aqueous layer, it shows the presence of porphobilinogen. If it moves to the lower layer, it denotes the presence of urobilinogen.

Testing a family member
Since acute porphyrias are autosomal dominant conditions, there is 50 % chance that the child may be affected if one of the parent has the disease. However, the disease may remain latent for a prolonged time. Latent cases can be diagnosed by measuring porphyrins and their precursors in urine, faces and blood, or measuring the various enzymes of the heme biosynthetic pathway. Young children may not show signs of their porphyria till puberty and laboratory tests may not even pick it up till then. Hence, it is safer to have to children follow the same precautions to minimize the risk. These children should be tested every two years from the age of 12 till they are 20 years old. If the tests are still negative, it is unlikely that the child may suffer from porphyria. However, the child may still have the defective gene, hence it is wise that no member of a porphyric family should take such drugs until essential.



Contributor Information and Disclosures

Ira Shah
Consultant Pediatrician, B.J.Wadia Hospital for Children, Mumbai, India


First Created : 2/28/2001
Last Updated : 10/1/2014

References

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