Many pitfalls in diagnosis of acute intermittent porphyria: a case report

N L R Indika,D M Vidanapathirana,U M T Piumika,E Jasinge,K L S P K M Jayasena Jayasena,W Kodikara Arachchi,R J Desnick,N D P D Chandrasiri,T Kesavan,I N Jayasinghe,H W Dilanthi,M Dissanayake,D Doheny,K D A V Gunarathne

doi:10.1186/s13104-018-3615-z

Abstract

BackgroundAcute intermittent porphyria is a rare autosomal dominant disorder caused by a deficiency of the enzyme, hydroxymethylbilane synthase. Recognition of acute neurovisceral attacks can be difficult due to the nonspecific nature of symptoms.Case presentationWe report a case of 33-year-old male patient who presented with recurrent episodes of severe abdominal pain, nausea, vomiting, constipation and numbness of bilateral lower limb extremities. These nonspecific neurovisceral attacks were subject to medical and surgical misdiagnoses of acute appendicitis, sinus tachycardia, renal calculi, drug-induced acute interstitial nephritis and two episodes of partial intestinal obstruction. The sixth acute attack raised the suspicion of an acute porphyria. Watson and Schwartz test was positive for porphobilinogen in urine. Mutation analysis by DNA sequencing of the extracted DNA of the proband revealed a previously reported missense mutation, c.517C>T encoding p.R173W in the HMBS gene, confirming the diagnosis of Acute Intermittent Porphyria. Four out of five family members who underwent targeted mutation analyses were mutation-positive.ConclusionThe most common clinical presentation of Acute Intermittent Porphyria is abdominal pain with neurovisceral manifestations which are common to several medical, psychiatric and surgical pathologies. This leads to underdiagnosis and misdiagnosis of this disorder, incorrect management, and severe complications. Therefore, a high index of suspicion and awareness of front line laboratory investigations are important for diagnosis. Definitive diagnosis enables implementation of strategies to prevent acute attacks, and also triggers genetic testing and genetic counseling of at-risk family members.

Highlights

Acute intermittent porphyria is a rare autosomal dominant disorder caused by a deficiency of the enzyme, hydroxymethylbilane synthase
The most common clinical presentation of Acute Intermittent Porphyria is abdominal pain with neurovisceral manifestations which are common to several medical, psychiatric and surgical pathologies. This leads to underdiagnosis and misdiagnosis of this disorder, incorrect management, and severe complications
Acute intermittent porphyria (AIP) is an autosomal dominant acute porphyria which is caused by mutations in the gene encoding hydroxymethylbilane synthase (HMBS), the third enzyme in the heme biosynthesis pathway

Summary

Conclusion

The most common clinical presentation of Acute Intermittent Porphyria is abdominal pain with neurovisceral manifestations which are common to several medical, psychiatric and surgical pathologies. This leads to underdiagnosis and misdiagnosis of this disorder, incorrect management, and severe complications. A high index of suspicion and awareness of front line laboratory investigations are important for diagnosis. Definitive diagnosis enables implementation of strategies to prevent acute attacks, and triggers genetic testing and genetic counseling of at-risk family members

Background

D Sister

Discussion and conclusions