Vitamin B12 deficiency-induced pseudothrombotic microangiopathy without macrocytosis presenting with acute renal failure: a case report

Adult Vitamin B12 Deficiency-Associated Pseudo-Thrombotic Microangiopathy: A Systematic Review of Case Reports

Cobalamin-deficient thrombotic microangiopathy or vitamin B12 deficiency presenting as pseudo-thrombotic microangiopathy is a rare disorder that can be misdiagnosed as thrombotic thrombocytopenic purpura. Patients with this condition are at risk of receiving unnecessary plasmapheresis with a potential delay in appropriate therapy with vitamin B12 supplementation. There are no established diagnostic criteria for this condition in clinical practice. We performed a systematic review of case reports published between January 2018 and January 2023 to analyze the clinical characteristics, risk factors, and patterns of laboratory markers to improve the diagnostic criteria for this condition.

Pseudo-thrombotic microangiopathy due to folate deficiency

Classically, deficiencies of vitamin B12 and folate are associated with megaloblastic anaemia. Additionally, vitamin B12 is able to cause a haemolytic anaemia in the form of pseudo-thrombotic microangiopathy (pseudo-TMA). Here, we present a case of a middle-aged woman with a history of Roux-en-Y gastric bypass who presented with dyspnoea and fatigue and was found to have thrombocytopenia and a non-immune haemolytic anaemia. Work-up for haemolytic uraemic syndrome, thrombotic thrombocytopenic purpura, paroxysmal nocturnal haemoglobinuria, infection, malignancy and autoimmune conditions was unremarkable. Her haemolytic anaemia and thrombocytopenia resolved with folate replenishment. She was diagnosed as likely having pseudo-TMA secondary to folate deficiency.

Concomitant Vitamin B1 and Vitamin B12 Deficiency Mimicking Thrombotic Thrombocytopenic Purpura

Vitamin B12 deficiency-induced pseudo-thrombotic thrombocytopenic purpura (pseudo-TTP) is a rare condition. In reported literature, most cases were due to pernicious anemia (confirmed by the presence of anti-parietal cells or anti-intrinsic factor antibodies). Nutritional vitamin B12 deficiency causing pseudo-TTP is a much rarer entity. Differentiating thrombotic thrombocytopenic purpura (TTP) cases from pseudo-TTP (from any cause) should be done as soon as possible since the etiology, treatment, and outcome are different. Hematological findings from pseudo-TTP (when associated with vitamin B12 deficiency) respond to B12 replacement but do not respond to plasmapheresis. Neurological symptoms are one of the criteria for TTP, and altered mentation or psychosis in these cases is presumed secondary to either TTP or vitamin B12 deficiency. However, neurological symptoms are more characteristic of TTP rather than pseudo-TTP. In the rarer subsets of patients concerned with nutritional deficiency and neuropsychiatric symptoms, prompt consideration of concomitant vitamin B1 deficiency and Wernicke encephalopathy is essential. Immediate empiric treatment with high-dose IV thiamine should be started. If unrecognized and left untreated, thiamine deficiency can cause rapid progression to irreversible neurological symptoms, coma, and death, despite hematological improvement with B12 replacement. We report a rare case of concomitant vitamin B12 and vitamin B1 deficiency presenting with confusion, severe hemolytic anemia, acute renal failure, diarrhea, and thrombocytopenia mimicking TTP.

Co-existence of Thrombotic Thrombocytopenic Purpura and Megaloblastic Anaemia: A Case-Based Review

Introduction

Thrombotic thrombocytopenic purpura is a rare and fatal thrombotic microangiopathy characterised by a pentad of microangiopathic haemolytic anaemia, thrombocytopenia, renal abnormalities, neurological abnormalities, and fever. Due to ineffective erythropoiesis, vitamin-B12 deficiency may rarely present as haemolytic anaemia.

Case report

We report a case of a 42-year-old vegetarian female presenting as vitamin B12 deficiency anaemia found to have concomitant TTP, responding to plasmapheresis, corticosteroids, and rituximab therapy.

Discussion

In this case of vitamin B12 deficiency with co-existent TTP, we hypothesise vitamin B12 deficiency as a contributory or precipitating factor for TTP. We reviewed similar cases in the literature to support this hypothesis. Timely detection of TTP and the initiation of treatment is of utmost importance as TTP has a high mortality when left untreated. The possible relationship with Vitamin B12 deficiency needs further exploration.

Fooled by the fragments: vitamin B12 deficiency masquerading as thrombotic thrombocytopenic purpura

Background: Thrombotic thrombocytopenic purpura (TTP) is a hematological emergency requiring prompt plasmapheresis. Conversely, vitamin B12 deficiency is a relatively benign diagnosis that can mimic microangiopathic hemolytic anemia, characterized by the presence of anemia, thrombocytopenia, indirect hyperbilirubinemia, markers of hemolysis, and schistocytes. This case series highlights the association of vitamin B12 deficiency and its TTP-like presentations.

Cases: The first case describes a 72-year-old man with shortness of breath and weakness. Diagnostics were notable for pancytopenia, schistocytes, and a low reticulocyte index. Intriguingly, total bilirubin was only mildly elevated however LDH and Haptoglobin were elevated and low, respectively. Additional diagnostic workup demonstrated an undetectable B12, elevated methylmalonic acid and elevated homocysteine. Initiation of B12 supplementation resolved his pancytopenia.

The second case describes a 57-year-old man with chest tightness, dyspnea on exertion, and night sweats. Diagnostic evaluation demonstrated pancytopenia, schistocytes, a low reticulocyte index, and a remarkably low B12. He had associated high methylmalonic acid and homocysteine levels, confirming the diagnosis. B12 supplementation resolved his pancytopenia.

Conclusion: The polysymptomatic presentation of vitamin B12 deficiency-induced pseudothrombotic microangiopathy highlights the vitamin’s role in essential physiological cellular functions. Rapid recognition of the underlying etiology of microangiopathic hemolytic anemia is necessary as treatment approaches diverge greatly.

Pancytopenia and TTP-like picture secondary to pernicious anaemia

A 21-year-old man presented to the emergency department with generalised weakness, weight loss and decreased appetite for few weeks. He had evidence of severe pancytopenia and haemolysis. His peripheral smear with many schistocytes was suspicious for thrombotic thrombocytopenic purpura (TTP). He was supported with blood transfusions and daily plasmapheresis. His platelet counts worsened despite 4 days of therapy. Bone marrow biopsy was significant for hypercellular bone marrow with megaloblastic changes. Further workup revealed normal ADAMTS13 level, low vitamin B12, positive intrinsic factor antibodies and high methylmalonic acid. Diagnosis of pernicious anaemia was established and he was started on daily treatment with intramuscular vitamin B12which subsequently improved his symptoms and haematological parameters. This report highlights the importance of checking vitamin B12level in patients presenting with pancytopenia and TTP-like picture before making a diagnosis of TTP.

Suspected Metformin-induced Cobalamin Deficiency Mimicking Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) can often be life threatening and requires timely diagnosis and prompt initiation of plasmapharesis. Cobalamin deficiency can closely mimic TTP and distinguishing between the two diseases can prove to be a diagnostic challenge. Previously, cobalamin-related pseudo-TTP has been associated with pernicious anemia, dietary insufficiency and hereditary disorders of cobalamin activation. Here in, we discuss the first case of suspected metformin-induced cobalamin deficiency causing pseudo-TTP. Our patient was a 36-year-old female with type 2 diabetes mellitus on metformin for eight years who presented with hemolytic anemia, thrombocytopenia, schistocytes and mild acute renal failure. The initial impression was TTP; however, further workup revealed very low serum cobalamin levels and elevated methylmalonic acid levels. Apart from metformin use, no other cause of cobalamin deficiency was identified. We recommended upper gastrointestinal endoscopy to definitively rule out pernicious anemia.