Mind the gap! An unusual metabolic acidosis

The concomitant use of paracetamol and flucloxacillin. A rare cause of high anion gap metabolic acidosis in the frail oldest old

OBJECTIVES

This article describes the occurrence of a high anion gap metabolic acidosis (HAGMA) in two older, female patients with a methicillin sensitive staphylococcus aureus (MSSA) infection. Both patients received flucloxacillin and paracetamol. Both of them initially improved but declined rapidly after two to three weeks of treatment. They developed a severe HAGMA resulting in their death. The objective of this article is to determine whether old age is a major risk factor for developing HAGMA when combining paracetamol with flucloxacillin.

METHODS

A literature study was conducted using the MEDLINE database, PubMed. The used MeSH terms were 'flucloxacillin, acetaminophen, glutathione synthetase deficiency and acidosis'. Furthermore, we used two cases to illustrate our findings.

RESULTS

The origin of the high anion gap metabolic acidosis is the accumulation of 5-oxoproline which is known to occur when combining flucloxacillin with paracetamol due to their interaction with different enzymes of the gamma glutamyl cycle. This leads to the depletion of glutathione and the formation of 5-oxoproline. This phenomenon has a higher risk of occurring in frail older adults as most of them have several predisposing risk factors which result in lower baseline glutathione reserve. These risk factors include old age, malnutrition, assigned female at birth, pre-existing kidney and/or liver dysfunction, uncontrolled diabetes and sepsis.

CONCLUSION

The purpose of this article is to raise awareness of this phenomenon and its higher occurrence in frail older adults, which hopefully will lead to an earlier diagnosis with a better outcome for the patient.

Flucloxacillin and paracetamol induced pyroglutamic acidosis

A 75-year-old woman was admitted to a regional hospital with an acute kidney injury (AKI) and nausea on a background of recent treatment for Staphylococcus aureus bacteraemia secondary to pneumonia. The treatment thereof resulted in a high anion gap metabolic acidosis (HAGMA). The pneumonia was initially treated with intravenous piperacillin and tazobactam and the patient transferred to a tertiary hospital. There, the diagnosis of S. aureus bacteraemia secondary to a pulmonary source was confirmed and treatment was changed to intravenous flucloxacillin and the patient was discharged to hospital in the home (HITH is a service that allows short-term healthcare at home to be provided to people who would otherwise need to be in hospital) to complete the antibiotic course. Five weeks after commencing flucloxacillin, the patient was referred back to hospital with nausea and worsening kidney function with an associated significant HAGMA. The patient has a background of chronic kidney disease and chronic back pain for which she was taking long-term paracetamol. The HAGMA was determined to be due to a pyroglutamic acidosis (PGA), deemed secondary to the combined use of paracetamol and flucloxacillin. This was subsequently confirmed with a plasma pyroglutamic acid concentration level of 7467 µmol/L (reference range 20-50 µmol/L) and a urinary level of 1700 mmol/mol creatinine (<110 mmol/mol creatinine). To our knowledge, this is the highest plasma and urinary levels published to date. Furthermore, considering the common use of paracetamol and penicillins, it is important to recognise HAGMA as a potential complication of co-administration of paracetamol and iso-oxylopenicillin. The HAGMA resolved after cessation of flucloxacillin despite the continuation of paracetamol and without administration of N-acetylcysteine. PGA-related HAGMA appears to be a unique potential side effect of iso-oxylopenicillin rather than other beta-lactams.

Acquired pyroglutamic acidosis due to long-term dicloxacillin and paracetamol use

An 85-year-old man with a background of transfusion-dependent chronic myelomonocytic leukaemia and chronic kidney disease stage III presented with symptomatic anaemia, acute kidney injury, sepsis and high anion gap metabolic acidosis (HAGMA). Initial treatment with intravenous antibiotics and blood transfusion was complicated by transfusion-associated circulatory overload, necessitating diuresis and non-invasive ventilation. Despite gradual clinical improvement, the patient’s HAGMA persisted, and no cause was identified on urine testing or renal ultrasound. As the patient was on long-term dicloxacillin for infective endocarditis prophylaxis and regular paracetamol, pyroglutamic acidosis (PGA) (5-oxoproline acidosis) was considered. This was later confirmed with elevated serum levels, and the HAGMA resolved following cessation of these medications. Although considered an uncommon cause of HAGMA, PGA is likely also under-recognised, and to our knowledge, this may be the second reported case in the context of dicloxacillin.

Pyroglutamic Acidemia: An Underrecognized and Underdiagnosed Cause of High Anion Gap Metabolic Acidosis - A Case Report and Review of Literature

Pyroglutamic acidemia (oxoprolinemia) is an underrecognized cause of high anion gap acidosis resulting from derangement in the gamma-glutamyl cycle. Pyroglutamic acidemia is most commonly diagnosed in the pediatric population in patients with inherited autosomal recessive enzyme deficiencies. However, acquired pyroglutamic acidemia can present in the adult population. Patients often present with confusion, nausea, and vomiting as well as an elevated anion gap metabolic acidosis. This article describes a case of acquired pyroglutamic acidemia and emphasizes the need to consider this entity.

Identifying the Components of Acidosis in Patients With Severe Plasmodium falciparum Malaria Using Metabolomics

BACKGROUND

Acidosis in severe Plasmodium falciparum malaria is associated with high mortality, yet the pathogenesis remains incompletely understood. The aim of this study was to determine the nature and source of metabolic acids contributing to acidosis in patients with severe falciparum malaria.

METHODS

A prospective observational study was conducted to characterize circulating acids in adults with P. falciparum malaria (n = 107) and healthy controls (n = 45) from Bangladesh using high-resolution liquid chromatography-mass spectrometry metabolomics. Additional in vitro P. falciparum culture studies were performed to determine if parasites release the acids detected in plasma from patients with severe malaria acidosis.

RESULTS

We identified previously unmeasured plasma acids strongly associated with acidosis in severe malaria. Metabolomic analysis of P. falciparum parasites in vitro showed no evidence that these acids are released by the parasite during its life cycle. Instead, 10 of the plasma acids could be mapped to a gut microbial origin. Patients with malaria had low L-citrulline levels, a plasma marker indicating reduced gut barrier integrity. Longitudinal data showed the clearance of these newly identified acids was delayed in fatal cases.

CONCLUSIONS

These data suggest that a compromise in intestinal barrier function may contribute significantly to the pathogenesis of life-threatening acidosis in severe falciparum malaria.

CLINICAL TRIALS REGISTRATION

NCT02451904.

Pyroglutamic acidosis as a cause for high anion gap metabolic acidosis: a prospective study

5-oxoprolinemia (pyroglutamic acid, PGA) in the absence of acetaminophen use has been rarely reported as a cause for high anion gap metabolic acidosis. We investigated the prevalence and risk factors for elevated PGA concentrations among hospitalized patients with high anion gap metabolic acidosis: We prospectively enrolled patients with high anion gap metabolic acidosis hospitalized in the department of medicine. For each patient we collected the main diagnosis, concurrent medications and laboratory parameters. Spot urine samples were tested for PGA concentration. Levels ≥63 µmol/mmol creatinine were considered elevated. Overall, forty patients were prospectively followed. Mean age was 66.9 (17.9) years. Four (6.3%) patients had a high urine PGA level and demonstrated also lower blood pH (7.2 vs 7.3, p = 0.05) and lower serum lactate concentration (17.5 mg/dl vs 23.0 mg/dl, p = 0.04). Additionally, the high PGA level group consisted of more patients with septic shock [2/4 (50%) vs 3/36 (8.3%)] with a trend towards significance (p = 0.07). In conclusion, PGA might have a role in patients with septic shock and acidosis. Being a treatable condition, PGA should be taken into consideration particularly when no other cause for high anion gap is identified.

Lesson of the month 1: A rare adverse reaction between flucloxacillin and paracetamol

Flucloxacillin, a beta-lactam antibiotic, is a commonly prescribed antibiotic for the treatment of infections caused by staphylococci and streptococci, most notably Staphylococcus aureus Paracetamol is one of the most dispensed medications by NHS England and is used for the treatment of fever and pain.1 However most doctors are unaware that concurrent use of these drugs can cause a potentially fatal drug interaction due to pyroglutamic acidosis (PGA), also known as 5-oxoprolinaemia. PGA is a rare cause of raised anion gap metabolic acidosis due to disruption of the γ-glutamyl cycle. We report the case of a patient with multiple comorbidities who developed PGA due to coadministration of paracetamol and flucloxacillin.

[The Sour Patient]

The Sour Patient Abstract. We report the case of a 75-year-old woman presenting with an elevated anion gap metabolic acidosis. The evaluation proved a 5-oxoprolin acidosis due to acetaminophen in therapeutic dose and concomitant risk factors such as malnutrition, chronic alcohol abuse, renal insufficiency, hepatopathy, and female sex. After stopping paracetamol medication and admission of bicarbonate and N-acetylcysteine, there was a rapid improvement in clinical symptoms and blood analysis.

Pyroglutamic acidosis in association with therapeutic paracetamol use

Long-term use of paracetamol (at therapeutic doses) can cause the accumulation of endogenous organic pyroglutamate, resulting in metabolic acidosis with an elevated anion gap. This occurs in the presence of malnutrition, infection, antibiotic use, renal failure and pregnancy. Given the prevalence of these risk factors, this condition is thought to be relatively common in a hospitalised population but is probably significantly underdiagnosed. Prompt recognition is essential because the condition is entirely reversible if the causative agents are withdrawn.Here we describe five cases of pyroglutamic acidosis that we have encountered in a tertiary referral hospital. Together they illustrate the common clinical risk factors and the excellent prognosis, once a diagnosis is made. We describe how a rudimentary acid-base analysis (calculation of the anion gap) usually leads to the diagnosis but how a more nuanced approach may be required in the presence of mixed acid-base disorders.

Metabolic acidosis and 5-oxoprolinuria induced by flucloxacillin and acetaminophen: a case report

Background

Frequent causes of high anion gap metabolic acidosis are well known: ethanol, methanol, and ethylene glycol intoxication; hyperglycemia; lactic or D-lactic acidosis; and impaired renal function. There are other causes, less frequent but also important. This report illustrates a rare case of a patient with increased anion gap metabolic acidosis due to a deficit of the γ-glutamyl cycle that led to 5-oxoproline (acid pyroglutamic) accumulation.

Case presentation

An 82-year-old white woman was admitted to our intensive care unit because of septic shock caused by right knee methicillin-sensitive Staphylococcus aureus-induced arthritis. She was treated for 10 days with flucloxacillin and rifampicin and developed metabolic acidosis with high anion gap. Her test results for methanol, ethanol, ethylene glycol, and acetylsalicylic acid were negative. Her glycemia, lactate level, and renal function were normal. However, the result of a urinary assay for pyroglutamate was positive. We concluded that the patient had metabolic acidosis induced by accumulation of 5-oxoproline. We modified her antibiotic treatment, administered acetylcysteine, and her acidosis resolved.

Conclusions

5-Oxoprolinuria (pyroglutamic acid accumulation) is a rare, probably underdiagnosed cause of transient metabolic acidosis with increased anion gap.

Acetaminophen toxicity and 5-oxoproline (pyroglutamic acid): a tale of two cycles, one an ATP-depleting futile cycle and the other a useful cycle

The acquired form of 5-oxoproline (pyroglutamic acid) metabolic acidosis was first described in 1989 and its relationship to chronic acetaminophen ingestion was proposed the next year. Since then, this cause of chronic anion gap metabolic acidosis has been increasingly recognized. Many cases go unrecognized because an assay for 5-oxoproline is not widely available. Most cases occur in malnourished, chronically ill women with a history of chronic acetaminophen ingestion. Acetaminophen levels are very rarely in the toxic range; rather, they are usually therapeutic or low. The disorder generally resolves with cessation of acetaminophen and administration of intravenous fluids. Methionine or N-acetyl cysteine may accelerate resolution and methionine is protective in a rodent model. The disorder has been attributed to glutathione depletion and activation of a key enzyme in the γ-glutamyl cycle. However, the specific metabolic derangements that cause the 5-oxoproline accumulation remain unclear. An ATP-depleting futile 5-oxoproline cycle can explain the accumulation of 5-oxoproline after chronic acetaminophen ingestion. This cycle is activated by the depletion of both glutathione and cysteine. This explanation contributes to our understanding of acetaminophen-induced 5-oxoproline metabolic acidosis and the beneficial role of N-acetyl cysteine therapy. The ATP-depleting futile 5-oxoproline cycle may also play a role in the energy depletions that occur in other acetaminophen-related toxic syndromes.

Arterial Blood Gases

Arterial blood gases (ABG) results reflect underlying pathology and interpretation of the results are often compounded by ongoing disease processes and clinical interventions. While ABG specimens should be analysed immediately for optimal results the Clinical and Laboratory Standards Institute (CLSI) has recommended a window of 30 minutes at room temperature from blood collection to ABG analysis. A fresh and simple approach to interpreting ABG is provided.