Nitrous oxide abuse leading to extreme homocysteine levels and thrombosis in young adults: a case series

Nitrous oxide abuse unmasking anti-phospholipid syndrome in a 24-year-old male with cerebral venous thrombosis and pulmonary thromboembolism: a case report

BACKGROUND

The abuse of nitrous oxide (N2O) as a recreational drug has become a growing concern, manifesting in various medical complications. Here, we report the first Korean case of cerebral venous thrombosis (CVT) and pulmonary thromboembolism (PTE) caused by nitrous oxide abuse and anti-phospholipid syndrome.

CASE PRESENTATION

A 24-year-old Korean man studying abroad in the USA presented to the emergency department with altered sensorium, gait disturbance, and involuntary leg movements. His history revealed escalating nitrous oxide inhalation from occasional use to daily intake of 100 balloons over six months. The patient's symptoms were initially attributed to cobalamin deficiency due to N2O abuse, leading to hyperhomocysteinemia and subsequent venous thrombosis, particularly CVT and PTE. However, the presence of Lupus Anticoagulant (LA) indicated a potential autoimmune or inflammatory process contributing to thrombotic complications, complicating the diagnosis. The patient's treatment involved cobalamin supplementation, anticoagulation therapy, and addressing associated substance abuse and depression. Notably, subsequent tests revealed persistent positive LA, highlighting the complexity of the case and the multifactorial nature of N2O-induced complications.

CONCLUSIONS

The mechanisms underlying N2O-induced thrombotic complications are elucidated, primarily involving the oxidation of cobalamin to its inactive form, leading to hyperhomocysteinemia and endothelial dysfunction. The association with LA suggests a potential autoimmune or inflammatory component, adding another layer of complexity to pathophysiology. This case underscores the importance of recognizing and managing the systemic thrombotic risk associated with N2O abuse. It highlights the need for heightened vigilance in diagnosing and managing associated complications, including CVT, and emphasizes the importance of comprehensive diagnostic and treatment approaches addressing both medical and psychiatric aspects. In conclusion, this case serves as a poignant reminder of the serious medical consequences of N2O abuse and underscores the importance of early recognition, comprehensive management, and ongoing surveillance to mitigate its adverse effects on individual health and public well-being.

Cerebral Venous Thrombosis and Nitrous Oxide Intoxication: Report of Two Cases and Review of the Literature

BACKGROUND

Cerebral venous thrombosis (CVT) has various risk factors, including contraception, pregnancy, neoplasia, and thrombophilia. Nitrous oxide (N₂O), historically used as an anesthetic and more recently as a recreational drug, has been associated with neurological complications such as myeloneuropathy and thromboembolic events. Here, we report two cases of CVT associated with N₂O use and provide a review of the literature on this association.

METHODS

We describe two local cases of CVT associated with N2O use and 10 additional cases identified by literature review.

RESULTS

Among the 12 patients, seven had co-existing CVT risk factors. Most patients reported chronic N2O use. Hyperhomocysteinemia was reported in nine patients. Management included anticoagulation, vitamin supplementation, cessation of N₂O use, and support for addiction or psychiatric care. The outcome was generally favorable, although one local case experienced CVT recurrence following a relapse in N₂O use.

CONCLUSIONS

These cases highlight an emerging association between CVT and N₂O use. Prompt recognition of this link is critical to recommend cessation of N₂O use, alongside anticoagulation therapy and consideration of vitamin supplementation to prevent complications and recurrence.

Tackling the growing burden of nitrous oxide-induced public health harms

Nitrous oxide has been increasing in popularity as a recreational drug in the past decade, and with this an increase in health harms related to nitrous oxide use, particularly nitrous oxide-induced myeloneuropathy. In response, governments in many countries have adopted new laws that either target the end user, by criminalising possession, or target suppliers. The effect of these measures remains to be seen, but the potential to exacerbate harm by targeting the user and thus affecting health-care-seeking behaviour is a concern. Education around the preventable harm from recreational use of nitrous oxide and tightening regulations on suppliers are essential in mitigating the increase in nitrous oxide-related health harms.

Nitrous oxide abuse direct measurement for diagnosis and follow-up: update on kinetics and impact on metabolic pathways

Recreational use of nitrous oxide (N2O) has become a major health issue worldwide, with a high number of clinical events, especially in neurology and cardiology. It is essential to be able to detect and monitor N2O abuse to provide effective care and follow-up to these patients. Current recommendations for detecting N2O in cases of recreational misuse and consumption markers are lacking. We aimed to update current knowledge through a review of the literature on N2O measurement and kinetics. We reviewed the outcomes of experiments, whether in preclinical models (in vitro or in vivo), or in humans, with the aim to identify biomarkers of intoxication as well as biomarkers of clinical severity, for laboratory use. Because N2O is eliminated 5 min after inhalation, measuring it in exhaled air is of no value. Many studies have found that urine and blood matrices concentrations are connected to ambient concentrations, but there is no similar data for direct exposure. There have been no studies on N2O measurement in direct consumers. Currently, patients actively abusing N2O are monitored using effect biomarkers (biomarkers related to the effects of N2O on metabolism), such as vitamin B12, homocysteine and methylmalonic acid.

Nitrous Oxide Use Precipitates Pulmonary Embolism: A Case Report

Nitrous oxide (N2O) has a lengthy history of use as an anesthetic and has recently found popularity as a recreational euphoric hallucinogen. The odorless, colorless, non-flammable gas interferes with Vitamin B12 resulting in a cascade of effects, including hyperhomocysteinemia. It has long been proposed that hyperhomocysteinemia adversely affects the cardiovascular system, producing atherogenic and prothrombotic diseases. In this case vignette, we describe a case in which a healthy patient presented with venous thromboembolism (VTE) that we suspect could have been precipitated by daily and significant recreational use of N2O. Anticoagulation therapy was given, and there was a significant improvement in the pulmonary emboli. As recreational use of N2O increases, it is essential to recognize that hyperhomocysteinemia may also produce a thrombotic state.

Metabolite correlation permutation after mice acute exposure to PM2.5: Holistic exploration of toxicometabolomics by network analysis

Many environmental toxicants can cause systemic effects, such as fine particulate matter (PM2.5), which can penetrate the respiratory barrier and induce effects in multiple tissues. Although metabolomics has been used to identify biomarkers for PM2.5, its multi-tissue toxicology has not yet been explored holistically. Our objective is to explore PM2.5 induced metabolic alterations and unveil the intra-tissue responses along with inter-tissue communicational effects. In this study, following a single intratracheal instillation of multiple doses (0, 25, and 150 μg as the control, low, and high dose), non-targeted metabolomics was employed to evaluate the metabolic impact of PM2.5 across multiple tissues. PM2.5 induced tissue-specific and dose-dependent disturbances of metabolites and their pathways. The remarkable increase of both intra- and inter-tissue correlations was observed, with emphasis on the metabolism connectivity among lung, spleen, and heart; the tissues' functional specificity has marked their toxic modes. Beyond the inter-status comparison of the metabolite fold-changes, the current correlation network built on intra-status can offer additional insights into how the multiple tissues and their metabolites coordinately change in response to external stimuli such as PM2.5 exposure.

Recreational nitrous oxide and thrombotic events: a case series

Background

The study aimed to elucidate the prevalence of nitrous oxide (N2O) usage in patients with unexplained venous thromboembolism (VTE), highlighting the potential association with hyperhomocysteinaemia (HHcy).

Methods

We conducted a retrospective study at the Royal London Hospital, examining cases of N2O-related VTE from March to August 2023. Among 50 patients identified, four (8%) had recent unprovoked VTE. Patient data were collected based on N2O ambulatory emergency care pathway admissions.

Results

Among the 50 patients identified, four (8%) had recent or concurrent VTE. Three were male (75%), with an ethnic distribution of 50% Asian or Asian British and 50% Black or Black British. Patients were distributed across quintiles of the index of multiple deprivation. All had actual or functional vitamin B12 deficiency.

Discussion

The association between N2O use and VTE requires further investigation, though a plausible mechanism involving HHcy has been proposed. Clinicians should be vigilant for VTE in N2O users, especially those presenting with unexplained symptoms. VTE prophylaxis may be worth considering, particularly if continued exposure to nitrous oxide is anticipated.

Conclusion

N2O misuse may increase the risk of VTE, warranting attention from healthcare providers. Further research is needed to elucidate this association and inform preventive strategies. Public awareness about the risks of N2O remains essential.

Does nitrous oxide addiction exist? An evaluation of the evidence for the presence and prevalence of substance use disorder symptoms in recreational nitrous oxide users

BACKGROUND

Prevalence of nitrous oxide (N2 O) use appears to be increasing in numerous countries worldwide, and excessive use has been associated with physical and mental problems. Because there currently is no consensus whether N2 O has addictive potential, we aimed to evaluate the evidence for the presence and prevalence of DSM-5 substance use disorder (SUD) symptoms in N2 O users.

ANALYSIS

A literature search was conducted to assess the evidence for the presence of any of the 11 DSM-5 SUD symptoms in N2 O users and the prevalence experiencing those symptoms. A substantial part of the studied N2 O users use more than intended (i.e. 46% to 98%) and spend a substantial amount of time using N2 O. At least some of the studied N2 O users experience interpersonal problems (i.e. 13% to 80%) and use N2 O in risky situations, such as driving under the influence. Evidence for the other criteria is either insufficient or inconclusive.

CONCLUSIONS

The literature base for the presence and prevalence of DSM-5 substance use disorder (SUD) symptoms in nitrous oxide (N2 O) users is limited and largely consists of qualitative studies and case studies, but it provides consistent evidence for the presence of at least four SUD criteria in heavy N2 O users. N2 O could well be addictive and should be treated as a potentially addictive substance until systematic assessments can provide evidence-based guidance to users, healthcare professionals and legislators.

Neurological complications of excessive recreational nitrous oxide use: a case series based on a text mining algorithm

BACKGROUND

The recreational use of nitrous oxide (N2O) has gained popularity over recent years. We present a case series of excessive N2O users with neurological complications.

METHODS

In this retrospective three-centre study, we used a text mining algorithm to search for patients who used N2O recreationally and visited a neurologist.

RESULTS

We identified 251 patients. The median duration of N2O use was 11 months (interquartile range [IQR], 3-24) and the median amount of N2O used per occasion 1.6 kg (IQR 0.5-4.0). Clinically, polyneuropathy (78%), myelopathy (41%), and encephalopathy (14%) were the most common diagnoses. An absolute vitamin B12 deficiency of < 150 pmol/L was found in 40% of cases. In 90%, at least one indicator of functional vitamin B12 status (vitamin B12, homocysteine, or methylmalonic acid) was abnormal. MRI showed signs of myelopathy in 30/55 (55%) of cases. In 28/44 (64%) of those who underwent electromyography, evidence of axonal polyneuropathy was found. Most (83%) patients were treated with vitamin B12 supplementation, and 23% were admitted to the hospital. Only 41% had follow-up for ≥ 30 days, and 79% of those showed partial or complete recovery.

CONCLUSIONS

In this case series of excessive N2O users, we describe a high prevalence of polyneuropathy, myelopathy, and encephalopathy. Stepwise testing for serum levels of vitamin B12, homocysteine, and methylmalonic acid may support the clinical diagnosis. Due to low sensitivity, MRI of the spinal cord and electromyography have limited value. Effective treatment should incorporate supplementation of vitamin B12 and strategies to prevent relapses in N2O use.

Nitrous Oxide-Induced Cerebral Venous Thrombosis: A Case Report, Potential Mechanisms, and Literature Review

Cerebral venous thrombosis can result from hypercoagulation, either genetic or acquired. Hyperhomocysteninemia was previously thought to be linked with thrombophilia, although this is still controversial to this present day. In recent years, there has been a notable surge in the recreational use of nitrous oxide, which could potentially lead to hyperhomocysteinemia. We present a case of a 19-year-old female who was diagnosed with cerebral venous thrombosis with intracerebral hemorrhage. She had a history of nitrous oxide abuse, which is known to cause dysfunction of vitamin B12. Additionally, we conducted a literature review of cerebral venous thrombosis following nitrous oxide usage. Investigation showed that her serum vitamin B12 level was <100 pg/mL (reference range 197-771 pg/mL), and homocysteine level was 100.6 µmol/L (reference range 5.0-15.0 µmol/L). After receiving a vitamin B12 supplement, both serum vitamin B12 and homocysteine levels returned to normal. No other risk factors for thrombophilia were detected. Previously reported cases predominantly demonstrated hyperhomocysteinemia. The most likely mechanism of her cerebral venous thrombosis was hyperhomocysteinemia due to vitamin B12 deficiency caused by nitrous oxide abuse. This finding supports the hypothesis that hyperhomocysteinemia can induce cerebral venous thrombosis.

Vitamin B12 Status in Recreational Users of Nitrous Oxide: A Systematic Review Focusing on the Prevalence of Laboratory Abnormalities

The recreational use of nitrous oxide (N₂O) as "laughing gas" is a growing problem. The chronic toxicity of N₂O is mainly due to its ability to oxidize vitamin B12, making it dysfunctional as a cofactor in metabolic pathways. This mechanism plays a major role in the development of neurological disorders in N₂O users. The assessment of vitamin B12 status in N₂O users is important but challenging due to the lack of decrease in total vitamin B12 in most cases despite genuine vitamin B12 functional deficiency. Other biomarkers, such as holotranscobalamin (holoTC), homocysteine (tHcy) and methylmalonic acid (MMA), are interesting candidates to properly assess vitamin B12 status. Here, we conducted a systematic review of case series in order to assess the prevalence of abnormal values of total vitamin B12, holoTC, tHcy and MMA in recreational N₂O users, which is an important prerequisite for determining the best screening strategy in future guidelines. We included 23 case series (574 N₂O users) from the PubMed database. Total circulating vitamin B12 concentration was low in 42.2% (95% confidence interval 37.8-46.6%, n = 486) of N₂O users, while 28.6% (7.5-49.6%, n = 21) of N₂O users had low circulating concentrations of holoTC. tHcy levels were elevated in 79.7% (75.9-83.5%, n = 429) of N₂O users, while 79.6% (71.5-87.7%, n = 98) of N₂O users had increased concentrations of MMA. In summary, the increases in tHcy and MMA were the most prevalent abnormalities, and should be measured alone or in combination in symptomatic N₂O users rather than total vitamin B12 or holoTC.