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

Acquired pyroglutamic acidaemia in a critically ill patient with chronic paracetamol use: A case report

Pyroglutamic acid is an endogenous organic acid and a metabolite in the γ-glutamyl cycle, involved in glutathione metabolism. Accumulation of pyroglutamic acid is a rare cause of high anion gap metabolic acidosis. There are multiple risk factors for pyroglutamic acid accumulation, such as chronic paracetamol use and sepsis. In this case report, we discuss how we came to this diagnosis, how it was subsequently managed and why it is an important consideration for critically ill patients with risk factors who are likely to end up in an intensive care setting. Pyroglutamic acid recognition and treatment could benefit patients in the critically ill population as pyroglutamic acid is a rare cause of high anion gap metabolic acidosis, which is likely under-recognised and easily treated. Inappropriate management of metabolic disorders can contribute to patient morbidity and mortality. Therefore, the recognition and appropriate management of pyroglutamic acidaemia could benefit patients with risk factors for its development in a critical care setting.

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.

Recurrent Pyroglutamic Acidosis in the Context of Undiagnosed Liver Cirrhosis-A Case Report

Metabolic associated fatty liver disease, previously known as nonalcoholic fatty liver disease, is the most common cause of chronic liver disease across all ethnic groups; however, it remains enormously underestimated.^{1 , 2} Sepsis, hepatotoxic medications and malnutrition in the acute settings on top of unknown cirrhosis can lead to decompensation and various metabolic complications. Pyroglutamic acidosis is a rarely recognised cause for unexplained high anion gap metabolic acidosis that is felt to be frequently underdiagnosed. Particular patients at risk include women, the elderly, those on regular paracetamol and those suffering with malnourishment or sepsis. Other risk factors include alcohol abuse and chronic liver disease (3). We present the case of a patient with recurrent episodes of pyroglutamic acidosis and encephalopathy in the context of undiagnosed nonalcoholic fatty liver disease with cirrhosis.

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.

High anion gap metabolic acidosis induced by cumulation of ketones, L- and D-lactate, 5-oxoproline and acute renal failure

INTRODUCTION

Frequent causes of high anion gap metabolic acidosis (HAGMA) are lactic acidosis, ketoacidosis and impaired renal function. In this case report, a HAGMA caused by ketones, L- and D-lactate, acute renal failure as well as 5-oxoproline is discussed.

CASE PRESENTATION

A 69-year-old woman was admitted to the emergency department with lowered consciousness, hyperventilation, diarrhoea and vomiting. The patient had suffered uncontrolled type 2 diabetes mellitus, underwent gastric bypass surgery in the past and was chronically treated with high doses of paracetamol and fosfomycin. Urosepsis was diagnosed, whilst laboratory analysis of serum bicarbonate concentration and calculation of the anion gap indicated a  HAGMA. L-lactate, D-lactate, β-hydroxybutyric acid, acetone and 5-oxoproline serum levels were markedly elevated and renal function was impaired.

DISCUSSION

We concluded that this case of HAGMA was induced by a variety of underlying conditions: sepsis, hyperglycaemia, prior gastric bypass surgery, decreased renal perfusion and paracetamol intake. Risk factors for 5-oxoproline intoxication present in this case are female gender, sepsis, impaired renal function and uncontrolled type 2 diabetes mellitus. Furthermore, chronic antibiotic treatment with fosfomycin might have played a role in the increased production of 5-oxoproline.

CONCLUSION

Paracetamol-induced 5-oxoproline intoxication should be considered as a cause of HAGMA in patients with female gender, sepsis, impaired renal function or uncontrolled type 2 diabetes mellitus, even when other more obvious causes of HAGMA such as lactate, ketones or renal failure can be identified.

Metabolic acidosis caused by concomitant use of paracetamol (acetaminophen) and flucloxacillin? A case report and a retrospective study

PURPOSE

A patient was identified with severe metabolic acidosis, a high anion gap and 5-oxoproline accumulation, probably caused by the simultaneous use of paracetamol (acetaminophen) and flucloxacillin. We wanted to investigate the necessity to control the interaction between both drugs with an automatic alert system.

METHODS

To investigate the relevance of the interaction of paracetamol and flucloxacillin, a retrospective study was conducted. Data on paracetamol and flucloxacillin prescriptions and laboratory data (pH, Na⁺, HCO₃^-, Cl^-, albumin and 5-oxoproline levels) were combined to assess the prevalence of acidosis, calculate the anion gap and analyse 5-oxoproline levels in clinically admitted patients using both drugs simultaneously.

RESULTS

In the 2-year study period, approximately 53,000 admissions took place in our hospital. One thousand and fifty-seven patients used paracetamol and flucloxacillin simultaneously, of which 51 patients (4.8%) had a serum pH ≤ 7.35. One patient, the same patient as presented in the case report, had a high anion gap and a toxic level of 5-oxoproline.

CONCLUSION

The prevalence of metabolic acidosis is very low and the only patient identified with the interaction was recognised during normal clinical care. We conclude that automatic alerts based on simultaneous use of paracetamol and flucloxacillin will generate too many signals. To recognise patients earlier and prevent severe outcomes, a warning system (clinical rule) based on paracetamol, flucloxacillin and pH measurement may be helpful. Early calculation of the anion gap can narrow the differential diagnosis of patients with metabolic acidosis and measurement of 5-oxoproline can explain acidosis due the interaction of paracetamol and flucloxacillin.

Quantification of paracetamol and 5-oxoproline in serum by capillary electrophoresis: Implication for clinical toxicology

High anion gap metabolic acidosis frequently complicates acute paracetamol overdose and is generally attributed to lactic acidosis or compromised hepatic function. However, metabolic acidosis can also be caused by organic acid 5-oxoproline (pyroglutamic acid). Paracetamol's toxic intermediate, N-acetyl-p-benzoquinoneimine irreversibly binds to glutathione and its depletion leads to subsequent disruption of the gamma glutamyl cycle and an excessive 5-oxoproline generation. This is undoubtedly an underdiagnosed condition because measurement of serum 5-oxoproline level is not readily available. A simple, cost effective, and fast capillary electrophoresis method with diode array detection (DAD) for simultaneous measurement of both paracetamol (acetaminophen) and 5-oxoproline in serum was developed and validated. This method is highly suitable for clinical toxicology laboratory diagnostic, allowing rapid quantification of acidosis inducing organic acid 5-oxoproline present in cases of paracetamol overdose. The calibration dependence of the method was proved to be linear in the range of 1.3-250μgmL^-1, with adequate accuracy (96.4-107.8%) and precision (12.3%). LOQ equaled 1.3μgmL^-1 for paracetamol and 4.9μgmL^-1 for 5-oxoproline.