Three different presentation of same pathophysiology

Hyperhomocysteinemia in acute hepatic porphyria (AHP) and implications for treatment with givosiran

INTRODUCTION

Homocysteine is a sulfur-containing amino acid formed in the intermediary metabolism of methionine. Amino acid metabolism and heme biosynthesis pathways are complexly intertwined. Plasma homocysteine elevation, hyperhomocysteinemia (HHcy), has been reported in patients with acute hepatic porphyria (AHP), a family of rare genetic disorders caused by defects in hepatic heme biosynthesis.

AREAS COVERED

This article summarizes published case series in which givosiran, a subcutaneously administered small interfering RNA approved for AHP treatment, appeared to exacerbate dysregulated homocysteine metabolism in patients with AHP. A comprehensive exploratory analysis of ENVISION trial data demonstrated that on a population level, givosiran increased homocysteine but with wide interpatient variations, and there is no proof of correlations between HHcy and changes in efficacy or safety of givosiran.

EXPERT OPINION

The strong correlation and co-increase of homocysteine and methionine suggest that HHcy associated with givosiran is likely attributable to the impaired trans-sulfuration pathway catalyzed by cystathionine β-synthase, which uses vitamin B6 as a cofactor. Data-based consensus supports monitoring total plasma homocysteine and vitamin B6, B12, and folate levels before and during givosiran treatment; supplementing with pyridoxine/vitamin B6 in patients with homocysteine levels >100 μmol/L; and involving patients with homocysteine levels >30 μmol/L in decisions to supplement.

An uncommon presentation of hyperhomocysteinemia and vitamin B12 deficiency: a case report

Introduction

Cerebral venous thrombosis is relatively rare and characterized by a wide spectrum of clinical features. It is more common in young adults with women affected more than men. The diagnosis of cerebral venous thrombosis is easier nowadays due to easy access to advanced neuroimaging techniques. Abnormalities in thrombophilic profile are associated with enhanced risk of cerebral venous thrombosis. It has varied etiologies such as hypercoagulable states, infection, dehydration, pregnancy, and substance abuse. Hyperhomocysteinemia is found to be closely associated with an enhanced risk of cerebral venous thrombosis.

Case presentation

Here we report a case of cerebral venous thrombosis secondary to hyperhomocysteinemia caused by vitamin B₁₂ deficiency in a 32-year-old Indo-Aryan man. A detailed coagulation workup led us to find the etiology of cerebral venous thrombosis in this patient who followed a strict vegetarian diet and had vitamin B₁₂ deficiency leading to hyperhomocysteinemia.

Conclusion

There are conflicting reports in the literature about the association of hyperhomocysteinemia, B₁₂ deficiency, and cerebral venous thrombosis but some reports point to a significant association. We conclude that further studies with a large sample size are required to analyze the effect of hyperhomocysteinemia and low vitamin B₁₂ on the risk of cerebral venous thrombosis.

Portal, superior mesenteric and splenic vein thrombosis secondary to hyperhomocysteinemia with pernicious anemia: a case report

INTRODUCTION

Acute portomesenteric vein thrombosis is an uncommon but serious condition with potential sequelae, such as small-bowel gangrene and end-stage hepatic failure. It is known to be caused by various pro-thrombotic states, including hyperhomocysteinemia. We describe what is, to the best of our knowledge, the first reported case of concomitant thrombosis of portal, superior mesenteric and splenic veins due to hyperhomocysteinemia secondary to pernicious anemia and no other risk factors.

CASE PRESENTATION

A 60-year-old Indian man presented with epigastric pain, diarrhea and vomiting. An abdominal imaging scan showed that he had concomitant pernicious anemia and concomitant portal, superior mesenteric and splenic vein thrombosis. A work-up for the patient's hypercoagulable state revealed hyperhomocysteinemia, an undetectable vitamin B12 level and pernicious anemia with no other thrombophilic state. He developed infarction with perforation of the small bowel and subsequent septic shock with multi-organ dysfunction syndrome, and he ultimately died due to progressive hepatic failure.

CONCLUSION

This report demonstrates that pernicious anemia, on its own, can lead to hyperhomocysteinemia significant enough to lead to lethal multiple splanchnic vein thrombosis. Our case also underscores the need to (1) consider portomesenteric thrombosis in the differential diagnosis of epigastric abdominal pain, (2) perform a complete thrombotic work-up to elucidate metabolic abnormalities that could be contributing to a pro-thrombotic state and (3) initiate aggressive measures, including early consideration of multi-visceral transplantation, in order to avoid decompensation and a significant adverse outcome.