Pseudohypokalaemia and pseudohypoxaemia in a patient with acute myeloid leukaemia

Spurious laboratory results are frequently encountered in patients with haematological disorders and lead to unnecessary additional laboratory investigations and inappropriate treatment. An 80-year-old woman, known with acute myeloid leukaemia, was admitted with suspected sepsis. Laboratory tests revealed a leukocyte count of 358 x 109/L, serum potassium concentration of 2.6 mmol/L and partial pressure of arterial oxygen of 5.3 kPa. The patient did not display any clinical or electrocardiographic features of hypokalaemia and there were no signs of respiratory distress. A diagnosis of pseudohypokalaemia and pseudohypoxaemia was made and inappropriate therapeutic interventions were avoided. Pseudohypokalaemia and pseudohypoxaemia should always be a consideration in patients with hyperleukocytosis due to haematological malignancies, especially when there are no clinical features to support these findings. The inappropriate administration of potassium in such cases may cause serious cardiac arrythmias

Improving the emergency management of hyperkalaemia

Medicine: Nephrolog

In-hospital mortality of HIV-positive patients with acute kidney injury a decade after the roll-out of anti-retroviral therapy in Cape Town, South Africa

Background: Acute kidney injury (AKI) in HIV-infected patients in sub-Saharan Africa is a common cause of hospitalisation and is associated with high morbidity and mortality. There is a paucity of comparative data regarding the outcomes of AKI in those patients with and without HIV infection from the African continent.Methods: This was a single-centre retrospective study of all consecutive adult patients with AKI referred to the renal unit at Tygerberg Hospital for the period January 2015 to December 2016. The diagnosis of AKI required evidence of the following: a recent normal serum creatinine and/or normal kidney sizes on ultrasound examination and/or granular casts on urine microscopy. Kaplan–Meier curves and logistic regression were used to assess survival and identify factors predicting mortality.Results: We identified a total of 291 patients with AKI of whom 116 (40%) were HIV positive. HIV-positive patients had a mortality rate of 34.5% vs. 29.1% in the HIV-negative patients (P = 0.34). At hospital admission, HIV-positive patients had a higher admission serum creatinine (551 μmol/L vs. 190 μmol/L, P < 0.01). Of those who died, the HIV-positive patients were younger (41 vs. 52 years, P < 0.01), predominantly Black (87.5% vs. 23.5%, P < 0.01) and were mostly admitted to medical wards (92.5% vs. 41.2%, P < 0.01). There was no difference in mortality related to the use of renal replacement therapy (P = 0.50). Logistic regression identified mixed ancestry (OR 2.47, P = 0.02), HIV infection (OR 2.69, P < 0.01) and surgical ward admission (OR 2.05, P = 0.03) as predictors of death.Conclusions: In-hospital mortality of AKI was high, and HIV infection was associated with a greater risk of death. This may be the result of late presentation of both the AKI as well as the HIV infection

Urine ‘picket fence’ crystals in ethylene glycol poisoning

A 46-year-old woman intentionally ingested ethylene glycol and overdosed on paracetamol. She had clinical and laboratory features suggestive of ethylene glycol poisoning, and examination of the urine revealed calcium oxalate monohydrate, or ‘picket fence’, crystals. She responded well to therapy that included haemodialysis. Clinicians should be aware that these crystals appear late during the evolution of ethylene glycol poisoning and, along with other clinical and laboratory findings, should prompt the initiation of haemodialysis

A descriptive study of patients with inflammatory myopathies at Tygerberg Academic Hospital and a review of current classifications

Introduction: Idiopathic inflammatory myopathy (IIM) is a rare chronic disease of skeletal muscle. Determining its exact prevalence is complicated by the lack of uniformity of the definition and hence the classification of this condition. Therapeutic choices vary considerably because of the paucity of randomized controlled trials for this condition. Aims: To determine the prevalence of inflammatory myopathy in our drainage area, categorise our cases and to describe their extra-muscular and extra-cutaneous manifestations; to examine the utility of current classifications of IIM in our setting and propose an alternative classification; and to review the details and the effectiveness of the therapies given. Methods: A retrospective, cross-sectional, descriptive study was conducted. Information was obtained from the records of patients attending the clinic between January to June 2008. Demographic, clinical and laboratory data were extracted using a standardised data sheet. Results: Out of 1495 patients, 31 subjects with IIM were found. Estimated prevalence was 15.5 per million population. There were 28 females (90%) and 3 males (10%). The mean age of the patients was 45.2 years. Six (19.4%) had dermatomyositis (DM), 2 (6.5%) had polymyositis (PM) and 23 (74.2%) had connective tissue disease-associated myopathy (CAM). Muscle power in most patients was 4/5 (72.2%). Interstitial lung disease was the most common extra-muscular-/extra-cutaneous feature (25.8%). Antinuclear antibodies (ANA) were positive in 24 (77.4%) patients. There was a statistically significant difference of creatinine phosphokinase (CPK) levels between DM/PM versus CAM at presentation (p=0.024). Conclusion: IIM in our study population is more common compared to previous reports in the literature. CAM is the commonest cause by far, a finding not previously noted. Malignancy-associated inflammatory myopathy is rare. Studies evaluating the muscle biopsy findings in patients with CAM are required. There is a need for a new classification - we propose the umbrella term “auto-immune inflammatory myopathy”. We confirmed that IIM is a chronic debilitating condition requiring long term immunosuppressive therapy

Knowledge of medical specialists on the emergency management of hyperkalaemia with a focus on insulin-based therapy

Introduction: Hyperkalaemia is a common electrolyte disorder in hospitalised patients and may cause life-threatening cardiac arrythmias and death. There is a lack of consensus regarding its optimal management, which may result in wide variations in practice and the guidance provided to junior staff. Methods: We conducted a survey on a Research Electronic Data Capture (REDCap) platform to evaluate the knowledge of medical specialists regarding the diagnosis and management of hyperkalaemia, with a focus on insulinbased therapy. A convenience sample of 70 specialists in nephrology, internal medicine, emergency medicine and critical-care medicine were invited to participate. Comparisons were also made between nephrologists and nonnephrologists. Results: A total of 51 medical specialists responded, of whom 47% were nephrologists. They were more likely to initiate therapy at a potassium concentration ([K]) of 6 mmol/L, whereas non-nephrologists tended to start at a lower concentration (P < 0.01). Half the respondents regarded blood gas machine measurements as providing an accurate measure of [K]. Non-nephrologists were more likely to perform an ECG before starting treatment (P = 0.02). All respondents regarded insulin and dextrose as the most effective and reliable means for shifting K. Only 22% monitored the serum glucose concentration beyond 2 hours following insulin-based therapy, and 22% thought that hypoglycaemia was an uncommon complication if dextrose also was administered. Conclusions: This is the first comprehensive survey to report on the knowledge of specialists regarding the emergency management of hyperkalaemia. There is a need to address knowledge gaps, particularly around the optimal and safe use of insulin-based therapies. Our findings and recommendations should be useful in informing the development of consensus guidelines and educational resources on hyperkalaemia. &nbsp

Outcomes of critically ill adult patients with continuous renal replacement therapy-requiring acute kidney injury in the Free State province of South Africa: the impact of HIV

Background: Continuous renal replacement therapy (CRRT)-requiring acute kidney injury (AKI) in critically ill adult patients frequently occurs in the intensive care unit and is associated with high morbidity and mortality. There is a paucity of epidemiological data regarding CRRT-requiring AKI in sub-Saharan Africa.Methods: We conducted a retrospective cohort study of all critically ill adult patients with CRRT-requiring AKI at Universitas Academic Hospital, Bloemfontein, during the period 1 July 2010 to 30 June 2014. The primary purpose was to determine the incidence of CRRT-requiring AKI. Secondary objectives were to record mortality, renal recovery and duration of CRRT.Results: The number of patients with CRRT-requiring AKI was 87 (1.1%) of the 7 709 patients admitted to the ICU over this 4-year period. Of these, 37 (43%) were HIV infected. The median age was 56 years (43 years in the HIV-infected versus 64 years in the HIV-uninfected group (P < 0.01). The majority of the HIV-infected patients were Black (89%). Metabolic acidosis together with pulmonary oedema and oliguria were the main indications for dialysis. The overall mortality was 31% with most of the deaths (82%) occurring in the HIV-positive patients. These patients had a mortality rate of 60% versus 10% among the uninfected (P < 0.01. Multivariate logistic regression identified female sex and HIV infection as independent predictors of mortality. The median duration of CRRT was 3 days and renal recovery occurred in 26% of patients.Conclusions: The incidence of CRRT-requiring AKI in critically ill adult patients at Universitas Academic Hospital was low. The overall mortality was relatively low when compared to that reported by others; however, it was relatively very high in the HIV-infected group

Acute kidney injury outcomes at 90 days at a South African academic hospital

Background: Acute kidney injury (AKI) remains a serious problem in Africa. Most studies from sub-Saharan Africa are retrospective in design and report on only short-term, in-hospital outcomes. There remains a paucity of prospective data on the long-term outcomes of AKI in sub-Saharan Africa. Methods: We performed a  prospective cohort study from 1 January to 30 June 2016. AKI was diagnosed and staged according to KDIGO AKI 2012 criteria. Patients attending an academic hospital in Cape Town, South Africa were followed up for 90 days or more. Outcome was a composite of either chronic kidney disease (CKD) (eGFR <60 mL/min/1.73 m2), end-stage kidney disease (ESKD) (eGFR <15 mL/min/1.73 m2) or death. Results: A total of 113 patients were included of whom 64 (57%) reached the composite outcome. Those reaching this outcome were older (47.5 years vs. 35 years, P = 0.02) and were more likely to have had a history of hypertension (35.9% vs. 16.3%, P = 0.02). The most common causes of AKI were sepsis (33%), drugs and toxins (16%) and glomerular disease (12%). Older age (OR 2.3, 95% CI 1.03–5.12, P = 0.04) and a history of hypertension (OR 2.9, 95% CI 1.15–7.17, P = 0.02) predicted the composite outcome on univariable logistic regression; however, only a history of hypertension was associated on the multivariable model (adjusted OR 1.27, 95% CI 1.04–1.56, P = 0.02). Conclusions: In African patients with AKI, the composite outcome of CKD, ESKD and death at 90 days or more was high. Interventions to prevent the progression of patients with CKD are needed because access to chronic renal replacement therapy in the public sector of South Africa is limited

Cyclophosphamide-induced melanonychia

A case of drug-induced melanonychia due to cyclophosphamide is described in a patient with lupus nephritis. This resolved completely at 20 weeks after stopping the drug. Clinicians should be aware of the causes of melanonychia, and, if drug-induced melanonychia is suspected, the offending drug should be stopped whenever possible

A method comparison study of a point-of-care blood gas analyser with a laboratory auto-analyser for the determination of potassium concentrations during hyperkalaemia in patients with kidney disease

Introduction: Hyperkalaemia is a common electrolyte disorder that may cause life-threatening cardiac arrythmias. We aimed to determine the agreement of potassium concentrations between GEM premier 3500 point-of-care blood gas analyser (POC-BGA) and Roche Cobas 6000 c501 autoanalyser in patients with hyperkalaemia. Methods: A prospective, cross-sectional study of all consecutive adult patients referred to the Renal Unit with a serum potassium concentration ≥ 5.5 mmol/L was performed. A total of 59 paired venous blood samples were included in the final statistical analysis. Passing-Bablok regression and Bland Altman analysis were used to compare the two methods. Results: The median laboratory auto-analyser potassium concentration was 6.1 (5.9-7.1) mmol/L as compared to the POC-BGA potassium concentration of 5.7 (5.5-6.8) mmol/L with a mean difference of - 0.43 mmol/L and 95% upper and lower limits of agreement of 0.35 mmol/L and - 1.21 mmol/L, respectively. Regression analysis revealed proportional systematic error. Test for linearity did not indicate significant deviation (P = 0.297). Conclusion: Although regression analysis indicated proportional systematic error, on Bland Altman analysis, the mean difference appeared to remain relatively constant across the potassium range that was evaluated. Therefore, in patients presenting to the emergency department with a clinical suspicion of hyperkalaemia, POC-BGA potassium concentrations may be considered a surrogate for laboratory auto-analyser measurements once clinicians have been cautioned about this difference