Errors in potassium measurement: a laboratory perspective for the clinician

Potential medical impact of unrecognized in vitro hypokalemia due to hemolysis: a case series

OBJECTIVES

The destruction of red cells during blood collection or with the processing of the sample continues to occur at a high rate, especially among emergency department (ED) patients. This can produce pre-analytical laboratory errors, particularly for potassium. We determined the incidence of hemolyzed samples and discuss the potential medical impact for hypokalemic patients who potassium level is artificially normal (pseudoeukalemia).

METHODS

Potassium results were obtained for a 6-month period. Using a measured hemolysis index (HI), hemolysis was present in 3.1 % for all potassium ordered (n=94,783) and 7.5 % for ED orders (n=22,770). Most of these samples were reported as having high normal result or were hyperkalemic. There were 22 hemolytic samples with a potassium of <3.5 mmol/L, and 57 hemolytic samples with a potassium in lower limit of normal (3.5-3.8 mmol/L). From this group, we examined the medical histories of 8 selected patients whose initially normal potassium levels were subsequently confirmed to have a potassium values that were below, at, or just above the lower limit of normal due to hemolysis.

RESULTS

The primary complaint for these patients were: necrotizing soft tissue infection, pancreatitis, volume overload from heart failure with reduced ejection fraction, hypertension treated with hydrochlorothiazide, and presence of a short bowel syndrome. A subsequent non-hemolyzed sample was collected demonstrating hypokalemia in all of these patients. Within these cases, there was a potential for harm had hemolysis detection not been performed.

CONCLUSIONS

We demonstrate the medical importance of detecting hemolysis for patients who have pseudoeukalemia. This is relevant because the HI cannot be obtained when electrolytes are tested using whole blood samples, and a normal potassium may lead to inappropriate patient management.

Practice Patterns and Outcomes of Potassium Repletion Thresholds during Critical Illness

Rationale: Potassium repletion is common in critically ill patients. However, practice patterns and outcomes related to different intensive care unit (ICU) potassium repletion strategies are unclear. Objectives: 1) Describe potassium repletion practices in critically ill adults; 2) compare the effectiveness of potassium repletion strategies; and 3) compare effectiveness and safety of specific potassium repletion thresholds on patient outcomes. Methods: This was a retrospective analysis of the PINC AI Healthcare Database (2016-2022), including all critically ill adults admitted to an ICU on Hospital Day 1 and with a serum potassium concentration measured on Hospital Day 2. We determined the frequency of potassium repletion (any formulation) at each measured serum potassium concentration in each ICU, then classified ICUs as having threshold-based (a large increase in potassium repletion rates at a specific serum potassium concentration) or probabilistic (linear relationship between serum concentration and the repletion probability) patterns of repletion. Between patients in threshold-based and probabilistic repletion ICUs, we compared outcomes (primary outcome: potassium repletion frequency). We reported unadjusted percentages per exposure group and the adjusted odds ratios (from hierarchical regression models) for each outcome. Among patients in threshold-based ICUs with the most common repletion thresholds (3.5 mEq/L and 4.0 mEq/L), we conducted regression discontinuity analyses to examine the effectiveness of potassium repletion at each potassium threshold. Results: We included 190,490 patients in 88 ICUs; 35.0% received at least one dose of potassium on the same calendar day. Rates of potassium repletion were similar between 22 threshold-based strategy ICUs (33.5%) and 22 probabilistic strategy ICUs (36.4%). There was no difference in the adjusted risk of potassium repletion between patients admitted to threshold-based strategy ICUs versus probabilistic strategy ICUs (adjusted odds ratio, 1.09; 95% confidence interval [CI], 0.76-1.57). In regression discontinuity analysis, crossing the 3.5 mEq/L threshold from high to low potassium levels resulted in a 39.1% (95% CI, 23.7-42.4) absolute increase in potassium repletion but no change in other outcomes. Similarly, crossing the 4.0 mEq/L threshold resulted in a 36.4% (95% CI, 22.4-42.2) absolute increase in potassium repletion but no change in other outcomes. Conclusions: Potassium repletion is common in critically ill patients and occurs over a narrow range of "normal" potassium levels (3.5-4.0 mEq/L); use of a threshold-based repletion strategy to guide potassium repletion in ICU patients is not associated with clinically meaningful differences in outcomes.

Treating Primary Aldosteronism-Induced Hypertension: Novel Approaches and Future Outlooks

Primary aldosteronism (PA) is the most common cause of secondary hypertension and is associated with increased morbidity and mortality when compared with blood pressure-matched cases of primary hypertension. Current limitations in patient care stem from delayed recognition of the condition, limited access to key diagnostic procedures, and lack of a definitive therapy option for nonsurgical candidates. However, several recent advances have the potential to address these barriers to optimal care. From a diagnostic perspective, machine-learning algorithms have shown promise in the prediction of PA subtypes, while the development of noninvasive alternatives to adrenal vein sampling (including molecular positron emission tomography imaging) has made accurate localization of functioning adrenal nodules possible. In parallel, more selective approaches to targeting the causative aldosterone-producing adrenal adenoma/nodule (APA/APN) have emerged with the advent of partial adrenalectomy or precision ablation. Additionally, the development of novel pharmacological agents may help to mitigate off-target effects of aldosterone and improve clinical efficacy and outcomes. Here, we consider how each of these innovations might change our approach to the patient with PA, to allow more tailored investigation and treatment plans, with corresponding improvement in clinical outcomes and resource utilization, for this highly prevalent disorder.

Impact of potassium test sample rejections on routine laboratory service, South Africa

Background

Accurate potassium measurements are necessary for effective clinical management of hyperkalaemia. Pre-analytical factors may affect laboratory measurements, leading to erroneous results and inappropriate patient management and negatively impact the efficiency and finances of laboratories and hospitals.

Objective

This study evaluated the impact of rejected potassium test requests on laboratory service.

Methods

We conducted a retrospective descriptive study to assess potassium test data at a public laboratory in Pretoria, Gauteng, South Africa, using samples collected from an academic hospital, peripheral hospitals, and outpatient clinics between January 2018 to December 2018. We assessed the relationship between reasons for rejection and health facility type, as well as financial implications for the laboratory.

Results

The potassium result rejection rate was 15.1% (29 806 samples), out of the 197 405 requests received. The most common reasons for rejection were old sample (> 1 day old) (41.4%; 12 348 rejections) and haemolysis (38.2%; 11 398 rejections). The most frequent reason for rejections at the central, academic hospital was haemolysis (42.0%), while old sample was the most common reason for rejection at peripheral hospitals (43.4%; 4119/9493 requests) and outpatient health facilities (57.2%; 7208/12 605 requests) (p = 0.022). The total cost of potassium sample rejection over the study period was substantial, given the resource constraints in this setting.

Conclusion

Peripheral hospitals and outpatient departments accounted for the majority of rejected potassium testing results, possibly resulting from delays in transportation; causing substantial financial impact on the laboratory. Improved sample collection, handling, and expedited transportation are recommended.

What this study adds

This study highlights the importance of appropriate sample collection and handling and the undesirable consequences of non-adherence to these pre-analytical considerations.

Implications of differences between point-of-care blood gas analyser and laboratory analyser potassium results on hyperkalaemia diagnosis & treatment

BACKGROUND

Hyperkalaemia is managed in the emergency department (ED) following measurement of potassium results by blood gas analysers (BGA) or laboratory analysers (LAB).

AIMS

To determine the prevalence of clinically significant differences between BGA and LAB potassium results and the impact on ED hyperkalaemia management.

METHODS

Retrospective analysis of time-matched ED BGA and LAB potassium samples from 2019 to 2020 (taken within 15 min, one or both results ≥6.0 mmol/L). Mean differences and 95% limits of agreement (LoA) were determined for pairs with one or both results ≥6.0 mmol/L and a separate 500 consecutive sample pairs.

RESULTS

Four hundred eighty-eight matched BGA and LAB samples met the inclusion criteria. Of these, 201 (41.2%) differed by ≤0.5 mmol/L, 169 (34.6%) included a haemolysed LAB sample, and 12 (2.5%) had an unreportable BGA sample. One hundred six (21.7%) pairs differed by >0.5 mmol/L, and 60/106 (57%) had normal LAB potassium results, but BGA indicated moderate/severe hyperkalaemia (two of these pairs received hyperkalaemia treatment). Of patients with a haemolysed LAB sample, or where pairs differed by >0.5 mmol, 48 were treated with insulin and five (10.4%) experienced hypoglycaemia. Mean differences and LoA for pairs with LAB results <6.0 mmol/L but BGA ≥6.0 mmol/L demonstrated unacceptable agreement, with 18 (25.7%) BGA results exceeding 8.0 mmol/L.

CONCLUSIONS

Potentially significant discordance may occur between BGA and LAB potassium results. Clinicians need to be aware of factors impacting both analytical methods' accuracy (such as poor venepuncture or sample handling, (K) EDTA interference) and undetectable haemolysis with BGA measurements. We recommend BGA hyperkalaemia be confirmed with LAB results using a non-haemolysed sample where time permits.

Erroneous potassium results: preanalytical causes, detection, and corrective actions

Potassium is one of the most requested laboratory tests. Its level is carefully monitored and maintained in a narrow physiological range. Even slightly altered potassium values may severely impact the patient's health, which is why an accurate and reliable result is of such importance. Even if high-quality analytics are available, there are still numerous ways in which potassium measurements may be biased, all of which occur in the preanalytical phase of the total laboratory testing process. As these results do not reflect the patient's in-vivo status, such results are referred to as pseudo-hyper/hypokalemia or indeed pseudo-normokalemia, depending on the true potassium result. Our goal in this review is to present an in-depth analysis of preanalytical errors that may result in inaccurate potassium results. After reviewing existing evidence on this topic, we classified preanalytical errors impacting potassium results into 4 categories: 1) patient factors like high platelet, leukocytes, or erythrocyte counts; 2) the sample type 3) the blood collection procedure, including inappropriate equipment, patient preparation, sample contamination and others and 4) the tube processing. The latter two include sample transport and storage conditions of whole blood, plasma, or serum as well as sample separation and subsequent preanalytical processes. In particular, we discuss the contribution of hemolysis, as one of the most frequent preanalytical errors, to pseudo-hyperkalemia. We provide a practical flow chart and a tabular overview of all the discussed preanalytical errors including possible underlying mechanisms, indicators for detection, suggestions for corrective actions, and references to the according evidence. We thereby hope that this manuscript will serve as a resource in the prevention and investigation of potentially biased potassium results.

Pseudohyperkalemia in chronic lymphocytic leukemia: Prevalence, impact, and management challenges

The term pseudohyperkalemia refers to a false elevation in serum potassium levels due to potassium release from cells in vitro. Falsely elevated potassium levels have been reported in patients with thrombocytosis, leukocytosis, and hematologic malignancies. This phenomenon has been particularly described in chronic lymphocytic leukemia (CLL). Leukocyte fragility, extremely high leukocyte counts, mechanical stress, higher cell membrane permeability related to an interaction with lithium heparin in plasma blood samples, and metabolite depletion due to a high leukocyte burden have been reported to contribute to pseudohyperkalemia in CLL. The prevalence of pseudohyperkalemia is up to 40%, particularly in the presence of a high leukocyte count (>50 × 109/L). The diagnosis of pseudohyperkalemia is often overlooked, which may result in unnecessary and potentially harmful treatment. The use of whole blood testing and point-of-care blood gas analysis, along with thorough clinical evaluation, may help differentiate between true and pseudohyperkalemic episodes.

Role of Acacia catechu and Scutellaria baicalensis in Enhancing Immune Function Following Influenza Vaccination of Healthy Adults: A Randomized, Triple-Blind, Placebo-Controlled Clinical Trial

OBJECTIVE

The study aimed to examine the role of an Acacia catechu and Scutellaria baicalensis formulation, UP446, on supporting immune function in response to influenza vaccination.

METHODS

A randomized, triple-blind, placebo-controlled, parallel study consisted of a 56-day intervention period with a 28-day pre-vaccination period, an influenza vaccination on Day 28 and 28-day post-vaccination period. Fifty healthy adults 40-80 years of age who had not received their flu vaccine were randomized to either UP446 or Placebo. At baseline, Days 28 and 56, immune and oxidative stress markers were measured in blood and a quality of life questionnaire was administered. Participants completed the Wisconsin Upper Respiratory Symptom Survey (WURSS)-24 daily.

RESULTS

In the post-vaccination period, total IgA and IgG levels increased in participants supplemented with UP446 vs. those on Placebo (p ≤ 0.026). As well, influenza B-specific IgG increased 19.4% from Day 28 to 56 and 11.6% from baseline at Day 56 (p ≤ 0.0075). Serum glutathione peroxidase (GSH-Px) was increased in the pre-vaccination period and from baseline at Day 56 with UP446 supplementation (p ≤ 0.0270).

CONCLUSION

These results suggest a 56-day supplementation with UP446 was beneficial in mounting a robust humoral response following vaccination. Increasing GSH-Px in the pre-vaccination period may help improve antioxidant functions and potentially mitigate the oxidative stress induced following vaccination.

Characterizing ability of serum potassium (K) and the serum K reference interval to flag hypokalemia or hyperkalemia as observed in plasma: a simulation study

OBJECTIVES

Serum potassium (K) exhibits a positive shift relative to plasma K due to a variable amount of K release associated with clotting. Because of this variation, plasma K results outside of the reference interval (RI) for plasma (hypokalemia or hyperkalemia) in individual samples may not produce classification-concordant results in serum according to the serum RI. We examined this premise from a theoretical standpoint by simulation.

DESIGN & METHODS

We used textbook K reference intervals for plasma (PRI = 3.4-4.5 mmol/L) and serum (SRI = 3.5-5.1 mmol/L). The difference between PRI and SRI is characterized by a normal distribution: serum K = plasma K + 0.35 ± 0.308 mmol/L. This transformation was applied by simulation to an observed patient data distribution for plasma K to generate a corresponding theoretical serum K distribution. Individual samples were tracked for comparison with respect to classification (below, within, above RI) for plasma and serum.

RESULTS

Primary data were an all-comers plasma K patient distribution (n = 41,768; median = 4.1 mmol/L; 7.1% below PRI (hypokalemia); 15.5% above PRI (hyperkalemia)). Simulation to obtain the associated serum K yielded a right-shifted distribution (median = 4.4 mmol/L; 4.8% below SRI; 10.8% above SRI). Sensitivity for detection in serum (flagged below SRI) for samples originating as hypokalemic in plasma was 45.7% (specificity = 98.3%). Sensitivity for detection in serum (flagged above SRI) for samples originating as hyperkalemic in plasma was 56.6% (specificity = 97.6%).

CONCLUSIONS

Simulation results indicate that serum K should best be thought of as an inferior substitute marker for plasma K. These results follow simply from the variable component of serum K compared to plasma K. Plasma should be the preferred specimen type for K assessment.

Age-appropriate potassium clearance from perinatal cerebrospinal fluid depends on choroid plexus NKCC1

Regulation of the volume and electrolyte composition of the cerebrospinal fluid (CSF) is vital for brain development and function. The Na-K-Cl co-transporter NKCC1 in the choroid plexus (ChP) plays key roles in regulating CSF volume by co-transporting ions and mediating same-direction water movements. Our previous study showed ChP NKCC1 is highly phosphorylated in neonatal mice as the CSF K+ level drastically decreases and that overexpression of NKCC1 in the ChP accelerates CSF K+ clearance and reduces ventricle size [1]. These data suggest that NKCC1 mediates CSF K+ clearance following birth in mice. In this current study, we used CRISPR technology to create a conditional NKCC1 knockout mouse line and evaluated CSF K+ by Inductively Coupled Plasma Optical Emission spectroscopy (ICP-OES). We demonstrated ChP-specific reduction of total and phosphorylated NKCC1 in neonatal mice following embryonic intraventricular delivery of Cre recombinase using AAV2/5. ChP-NKCC1 knockdown was accompanied by a delayed perinatal clearance of CSF K+. No gross morphological disruptions were observed in the cerebral cortex. We extended our previous results by showing embryonic and perinatal rats shared key characteristics with mice, including decreased ChP NKCC1 expression level, increased ChP NKCC1 phosphorylation state, and increased CSF K+ levels compared to adult. Collectively, these follow up data support ChP NKCC1's role in age-appropriate CSF K+ clearance during neonatal development.

2023 AAHA Selected Endocrinopathies of Dogs and Cats Guidelines

Canine and feline endocrinopathies reflect an endocrine gland disease or dysfunction with resulting hormonal abnormali ties that can variably affect the patient's wellbeing, quality of life, and life expectancy. These guidelines provide consensus recommendations for diagnosis and treatment of four canine and feline endocrinopathies commonly encountered in clini cal practice: canine hypothyroidism, canine hypercortisolism (Cushing's syndrome), canine hypoadrenocorticism (Addi son's disease), and feline hyperthyroidism. To aid the general practitioner in navigating these common diseases, a stepwise diagnosis and treatment algorithm and relevant background information is provided for managing each of these diseases. The guidelines also describe, in lesser detail, the diagnosis and treatment of three relatively less common endo crinopathies of cats: feline hyperaldosteronism, feline hypothyroidism, and feline hyperadrenocorticism. Additionally, the guidelines present tips on effective veterinary team utilization and client communication when discussing endocrine cases.

Pseudohyperkalemia associated with essential thrombocytosis; a hint for better clinical practice

A 75-year-old man was admitted with a diagnosis of diabetic ketoacidosis and hyperkalemia. During the treatment, he developed refractory hyperkalemia. Following our review, diagnosis of pseudohyperkalaemia secondary to thrombocytosis was made. We report this case to remind the importance of clinical suspicion of this phenomenon to prevent its serious consequences.

A New Perspective to Longstanding Challenges with Outpatient Hyperkalemia: A Narrative Review

Purpose of Review

Outpatient hyperkalemia is a common problem with potentially deadly consequences. Potassium level thresholds to treat outpatient hyperkalemia are unstandardized and variable, leaving health care providers to rely on their own clinical judgment. This narrative review highlights the challenges of outpatient hyperkalemia management and includes recommendations for future studies that may standardize treatment, improve patient outcomes, and optimize health care utilization.

Sources of Information

PubMed, Google Scholar, and the reference lists of identified articles were used to include English, peer-reviewed studies and guidelines for this review.

Methods

This narrative review examines outpatient hyperkalemia from both a laboratory and clinical perspective. In addition to peer-reviewed literature, guidelines and expert consensus statements were included to highlight the inconsistencies and paucity of evidence that health care providers rely on to make clinical decisions.

Key Findings

There are multiple reasons why outpatient hyperkalemia management is both challenging and sub-optimal. Clinicians must discern if the potassium level result is accurate and, if so, does the result warrant referral to the emergency department. Factitious hyperkalemia, or falsely elevated potassium level results due to analytical errors, occurs frequently, but there are no ways to identify it other than for hemolyzed samples. Additionally, guidelines and expert panels are inconsistent on the thresholds for treatment and the management of hyperkalemia. Finally, there are inconsistencies between laboratories as to when and how providers are notified of results, and the suggested thresholds for urgent management. A study that integrates the expertise of clinical biochemists and clinicians is needed to inform evidence-based guidelines for the management of outpatient hyperkalemia.

Limitations

This was a comprehensive review of what is known and what still needs to be understood for the management of outpatient hyperkalemia. A formal tool to assess the quality of the included studies was not used and selection bias may have occurred.

Is There a Risk of Misinterpretation of Potassium Concentration from Undetectable Hemolysis Using a POCT Blood Gas Analyzer in the Emergency Department?

Background and Objectives: Hemolysis is reported to be present in up to 10% of blood gas specimens in the central lab; however, few data on the incidence of hemolysis using a point-of-care testing (POCT) blood gas analysis are available in the setting of the emergency department. The aims of this study were: (1) to analyze the prevalence of hemolysis in blood gas samples collected in the ED using a POCT device; and (2) to evaluate the impact of hemolysis on blood sample results and its clinical consequences. Materials and Methods: We collected 525 consecutive POCT arterial blood gas samples using syringes with electrolyte-balanced heparin within 3 different EDs in the metropolitan area of Rome. Immediately after the collection, the blood samples were checked for the presence of hemolysis with a POCT instrument (i.e., HEMCHECK, H-10 ®). The samples were then subsequently processed for blood gasses, and an electrolytes analysis by a second operator blinded for the hemolysis results. A venous blood sample was simultaneously collected, analyzed for it’s potassium value, and used as a reference. Results: Of the samples, 472 were considered for the statistics, while 53 were excluded due to the high percentage of hemolysis due to operator fault in carrying out the measurement. The final mean hemolysis per operator was 12% (±13% SD), and the total final hemolysis was 14.4%.Potassium (K+) was significantly higher in the hemolyzed group compared with the non-hemolyzed sample (4.60 ± 0.11 vs. 3.99 ± 0.03 mEq/L; p < 0.001), and there were differences between arterial potassium versus venous potassium (D(a-v) K+, 0.29 ± 0.06 vs.−0.19 ± 0.02 mEq/L, p < 0.01). A Bland−Altman analysis confirmed that hemolysis significantly overestimated blood potassium level. Conclusion: Almost 12% of POCT blood gas analysis samples performed in the ED could be hemolyzed, and the presence of this hemolysis is not routinely detected. This could cause an error in the interpretation of the results, leading to the consideration of potassium concentrations being below the lower limit within the normal limits and also leading to the diagnosis of false hyperkalemia, which would have potential clinical consequences in therapeutic decision-making in the ED. The routine use of a POCT hemolysis detector could help prevent any misdiagnoses.

Exploring the K isotope composition of Göttingen minipig brain regions, and implications for Alzheimer's disease

Natural stable metal isotopes have shown utility in differentiation between healthy and diseased brain states (e.g. Alzheimer's disease, AD). While the AD brain accumulates some metals, it purges others, namely K (accompanied by increased serum K, suggesting brain-blood transferal). Here, K isotope compositions of Göttingen minipig brain regions for two AD models at midlife are reported. Results indicate heavy K isotope enrichment where amyloid beta (Aβ) accumulation is observed, and this enrichment correlates with relative K depletion. These results suggest preferential efflux of isotopically light K+ from the brain, a linkage between brain K concentrations and isotope compositions, and linkage to Aβ (previously shown to purge cellular brain K+). Brain K isotope compositions differ from that for serum and brain K is much more abundant than in serum, suggesting that changes in brain K may transfer a measurable K isotope excursion to serum, thereby generating an early AD biomarker.

Cells Gone Wild: A Case Report on Missed Acute Leukemia and Subsequent Disseminated Intravascular Coagulation in the Emergency Department

Introduction: Emergency physicians must maintain a broad differential when seeing patients in the emergency department (ED). Occasionally, a patient may have an undiagnosed, life-threatening medical condition not related to the presenting chief complaint. It is imperative to review all ordered laboratory tests and any available previous laboratory values to assess for any abnormalities that may warrant further evaluation. Case Report: This case report is regarding the missed diagnosis of acute leukemia and subsequent disseminated intravascular coagulation in a 27-year-old male who presented to multiple EDs with the unrelated chief complaint of finger ring entrapment. This patient ultimately succumbed to his illness. Conclusion: When evaluating patients in the ED, it is important to review any prior available test results for abnormalities, even if the results do not specifically correlate with the chief complaint. Emergency physicians must remain vigilant to avoid missing a critical diagnosis.

Cells Gone Wild: A Case Report on Missed Acute Leukemia and Subsequent Disseminated Intravascular Coagulation in the Emergency Department

INTRODUCTION

Emergency physicians must maintain a broad differential when seeing patients in the emergency department (ED). Occasionally, a patient may have an undiagnosed, life-threatening medical condition not related to the presenting chief complaint. It is imperative to review all ordered laboratory tests and any available previous laboratory values to assess for any abnormalities that may warrant further evaluation.

CASE REPORT

This case report is regarding the missed diagnosis of acute leukemia and subsequent disseminated intravascular coagulation in a 27-year-old male who presented to multiple EDs with the unrelated chief complaint of finger ring entrapment. This patient ultimately succumbed to his illness.

CONCLUSION

When evaluating patients in the ED, it is important to review any prior available test results for abnormalities, even if the results do not specifically correlate with the chief complaint. Emergency physicians must remain vigilant to avoid missing a critical diagnosis.

Markedly increased small-sized megakaryocytes and platelets count in the circulation with pseudo-hyperkalemia following splenectomy

Megakaryocytes are common in the bone marrow and appear less often in circulation. Most studies on circulatory megakaryocytes have implicated myelodysplastic syndromes and myeloproliferative disorders because of disruption of the bone marrow barrier and extramedullary hematopoiesis that is commonly seen in the spleen. As myeloproliferative disorders progress, particularly in the absence of the spleen, it is very likely that considerable numbers of megakaryocytes are present in the circulation. Myeloproliferation is associated with essential thrombocytosis or leukocytosis and is the leading cause of pseudo-hyperkalemia followed by reactive thrombocytosis due to splenectomy, rheumatoid arthritis, and renal cancer. The simultaneous measurement of plasma potassium is required when the platelet count exceeds 500 × 10⁹/L and the level of serum potassium is  > 5.4 mmol/L.

Adding eosinophil count to EMERALD rules predicts subarachnoid haemorrhage better in emergency department

BACKGROUND

Subarachnoid haemorrhage (SAH) clinical decision rules can provide successful results in the differential diagnosis of non-traumatic headache.

AIM

The aim of this study is to investigate whether a laboratory parameter that can be added to clinical decision-making rules can better predict subarachnoid haemorrhages in patients presenting to the emergency department with headache.

METHODS

We conducted a retrospective cohort study between March 2017 and March 2019. Patients over the age of 18 who admitted to the emergency department with non-traumatic, acute headache last 14 days before admission and evaluated by imaging and laboratory studies were included in the study.

RESULTS

A total of 867 patients were included and 141 of them had SAH. In detecting the SAH, Ottawa SAH rule sensitivity (85.1%), specificity (47.1%), positive predictive value (PPV) (23.8%) and negative predictive value (NPV) (94.2%), and for EMERALD SAH, rule sensitivity (96.4%), specificity (43.2%), PPV (24.8%) and NPV (98.4%). In the regression analysis, statistically significant result was obtained to exclude the diagnosis of SAH with the decrease in the eosinophil value (cutoff < 0.085 10^3/µL, OR: 0.011, 95% CI: 0.001-0.213, p = 0.003). When eosinophil value was added to EMERALD SAH rule, it provided a 100% of sensitivity, a 38.4% of specificity, a 24% of PPV and a 100% of NPV in detecting the SAH.

CONCLUSIONS

EMERALD SAH rule plus eosinophil, which offers 100% sensitivity and NPV for predicting SAH in adult non-traumatic headaches, may be recommended as a successful and practical decision rule for clinical use according to the Ottawa and EMERALD SAH rule.

Point-of-care and self-testing for potassium: recent advances

Potassium is an important bodily electrolyte which is kept within tight limits in health. Many medical conditions as well as commonly-used drugs either raise or lower blood potassium levels, which can be dangerous or even fatal. For at-risk patients, frequent monitoring of potassium can improve safety and lifestyle, but conventional venous blood draws are inconvenient, don't provide a timely result and may be inaccurate. This review summarises current solutions and recent developments in point-of-care and self-testing potassium measurement technologies, which include devices for measurement of potassium in venous blood, devices for home blood collection and remote measurement, devices for rapid home measurement of potassium, wearable sensors for potassium in interstitial fluid, in sweat, in urine, as well as non-invasive potassium detection. We discuss the practical and clinical applicability of these technologies and provide future outlooks.

Impact of recentrifugation of blood collection tubes on chemistry and immunochemistry analytes after 24 and 72 hours of refrigerated storage on the Roche Cobas 8000 platform

BACKGROUND

We discovered that blood collection tubes (BCTs) were inadvertently recentrifuged due to improper placement on our automated preanalytical system. This study was undertaken to determine the impact of recentrifugation of blood specimens collected in serum separator (SSTs) and plasma separator (PSTs) tubes after refrigerated storage for 24 and 72 h on the concentrations of chemistry and immunochemistry analytes.

METHODS

Blood was collected from 20 volunteers in SSTs and PSTs, centrifuged, and 36 chemistry and 14 immunochemistry analytes were measured at baseline in single-centrifuged tubes on a Roche Cobas 8000 chemistry platform. After baseline testing, the BCTs were refrigerated for 24 or 72 h, recentrifuged and retested. The results were compared to the single-centrifuged tubes for statistical significance.

RESULTS

Recentrifugation of BCTs after 24 or 72 h of refrigerated storage showed statistically significant increases in lactate dehydrogenase activity and potassium concentration and statistically significant decreases in glucose (except in SSTs after 24 h of refrigerated storage) and CO₂ concentration, but no significant differences in immunochemistry analyte concentrations.

CONCLUSION

It may be safe to report most routine chemistry and immunochemistry analyte concentrations from recentrifuged SSTs and PSTs on the Roche Cobas 8000, which may save time and costs associated with recollection and retesting.

Pseudohyperkalemia Associated With Leukemia

Elevated potassium levels can be a life-threatening emergency. We describe a case of falsely elevated serum potassium level in a patient with leukemia, which was suspected to be falsely elevated because the patient was asymptomatic with a normal electrocardiogram (EKG). Common reasons behind such a discrepancy in leukemia patients are the use of a tourniquet before collection, use of vacuum/pneumatic tubes for transportation, prolonged periods of incubation, use of heparin for sample collection, and processing of samples via centrifugation. Since the process is related to the method of collection and processing, we recommend using rapid point of care testing in such cases to differentiate between false and true potassium elevation, as it is a well-validated tool. Moreover, there is a good correlation between potassium measured with the blood gas, point of care, and central laboratory analyzers when the concentration of potassium is above 3 mEq/L.

Hematological Malignancies and the Kidney

The incidence of hematologic malignancies is on the rise worldwide. Kidney disease is ubiquitous in patients with hematologic malignancies, encompassing a wide spectrum of disorders involving each kidney compartment, including the vasculature, tubules, interstitium, and glomerulus, and there is significant overlap of kidney involvement with each hematologic malignancy. Vascular disorders include both microvascular and macrovascular damage, via thrombotic microangiopathy, hyperleukocytosis, hyperviscosity, and cryoglobulinemia. The tubulointerstitial compartment may be affected by prerenal azotemia and acute tubular injury, but malignant infiltration, tumor lysis syndrome, extramedullary hematopoiesis, cast nephropathy, granulomatous interstitial nephritis, and lysozymuria should be considered in certain populations. Obstructive uropathy may occur due to nephrolithiasis or retroperitoneal fibrosis. Glomerular disorders, including membranoproliferative, membranous, minimal change, and focal segmental glomerulosclerosis, can rarely occur. By understanding how each compartment may be affected, care can best be optimized for these patients. In this review, we summarize the widely varied etiologies of kidney diseases stratified by kidney compartment and hematologic malignancy, focusing on demographics, pathology, pathophysiology, mechanism, and outcomes. We conclude with common electrolyte abnormalities associated with hematologic malignancies.

Incidental findings in UK healthy volunteers screened for a COVID-19 vaccine trial

The safety of novel therapeutics and vaccines are typically assessed in early phase clinical trials involving "healthy volunteers." Abnormalities in such individuals can be difficult to interpret and may indicate previously unrecognized medical conditions. The frequency of incidental findings (IFs) in healthy volunteers who attend for clinical trial screening is unclear. To assess this, we retrospectively analyzed data for 1838 "healthy volunteers" screened for enrolment in a UK multicenter, phase I/II severe acute respiratory syndrome-coronavirus 2 (SARS-COV-2) vaccine trial. Participants were predominantly White (89.7%, 1640/1828) with a median age of 34 years (interquartile range [IQR] = 27-44). There were 27.7% of participants (510/1838) who had at least one IF detected. The likelihood of identifying evidence of a potential, new blood-borne virus infection was low (1 in 238 participants) compared with identification of an elevated alanine transaminase (ALT; 1 in 17 participants). A large proportion of participants described social habits that could impact negatively on their health; 21% consumed alcohol in excess, 10% were current smokers, 11% described recreational drug use, and only 48% had body weight in the ideal range. Our data demonstrate that screening prior to enrollment in early phase clinical trials identifies a range of IFs, which should inform discussion during the consent process. Greater clarity is needed to ensure an appropriate balance is struck between early identification of medical problems and avoidance of exclusion of volunteers due to spurious or physiological abnormalities. Debate should inform the role of the trial physician in highlighting and advising about unhealthy social habits.

Point-of-care artificial intelligence-enabled ECG for dyskalemia: a retrospective cohort analysis for accuracy and outcome prediction

Dyskalemias are common electrolyte disorders associated with high cardiovascular risk. Artificial intelligence (AI)-assisted electrocardiography (ECG) has been evaluated as an early-detection approach for dyskalemia. The aims of this study were to determine the clinical accuracy of AI-assisted ECG for dyskalemia and prognostic ability on clinical outcomes such as all-cause mortality, hospitalizations, and ED revisits. This retrospective cohort study was done at two hospitals within a health system from May 2019 to December 2020. In total, 26,499 patients with 34,803 emergency department (ED) visits to an academic medical center and 6492 ED visits from 4747 patients to a community hospital who had a 12-lead ECG to estimate ECG-K⁺ and serum laboratory potassium measurement (Lab-K⁺) within 1 h were included. ECG-K⁺ had mean absolute errors (MAEs) of ≤0.365 mmol/L. Area under receiver operating characteristic curves for ECG-K⁺ to predict moderate-to-severe hypokalemia (Lab-K⁺ ≤3 mmol/L) and moderate-to-severe hyperkalemia (Lab-K⁺ ≥ 6 mmol/L) were >0.85 and >0.95, respectively. The U-shaped relationships between K⁺ concentration and adverse outcomes were more prominent for ECG-K⁺ than for Lab-K⁺. ECG-K⁺ and Lab-K⁺ hyperkalemia were associated with high HRs for 30-day all-cause mortality. Compared to hypokalemic Lab-K⁺, patients with hypokalemic ECG-K⁺ had significantly higher risk for adverse outcomes after full confounder adjustment. In addition, patients with normal Lab-K⁺ but dyskalemic ECG-K⁺ (pseudo-positive) also exhibited more co-morbidities and had worse outcomes. Point-of-care bloodless AI ECG-K⁺ not only rapidly identified potentially severe hypo- and hyperkalemia, but also may serve as a biomarker for medical complexity and an independent predictor for adverse outcomes.

Effects of handling and storage on potassium concentration in plasma and serum samples obtained from cats

OBJECTIVE

To compare potassium concentrations in feline plasma and serum samples analyzed promptly after collection or after 20 to 28 hours of refrigerated storage.

ANIMALS

41 cats.

PROCEDURES

A venous blood sample was obtained from each cat. Aliquots were placed in 2 tubes without anticoagulant (blood was allowed to clot to derive serum) and 2 tubes with heparin (to derive plasma). One serum and 1 plasma sample were kept at room temperature and analyzed within 60 minutes after collection (baseline); the other serum and plasma samples were analyzed after 20 to 28 hours of refrigerated storage. At both time points, serum and plasma potassium concentrations were measured.

RESULTS

Median baseline serum potassium concentration (4.3 mmol/L) was significantly higher than median baseline plasma potassium concentration (4.1 mmol/L). The median difference between those values was 0.4 mmol/L (95% CI, 0.2 to 0.5 mmol/L). Compared with their respective baseline measurements, the median serum plasma concentration (4.8 mmol/L) and median plasma potassium concentration (4.6 mmol/L) were higher after 20 to 28 hours of refrigeration.

CLINICAL RELEVANCE

Results indicated that with regard to potassium concentration in feline blood samples, clotting or refrigerated storage for 20 to 28 hours results in a significant artifactual increase. Detection of an unexpectedly high potassium concentration in a cat may represent pseudohyperkalemia, especially if the blood sample was placed in a no-additive tube, was stored for 20 to 28 hours prior to analysis, or both.

Sulfamethoxazole-Trimethoprim and Hyperkalemia in an Infant

Hyperkalemia is a potentially life-threatening electrolyte abnormality in both children and adults. In the setting of elevated serum potassium concentrations, cardiac conduction disturbances and cardiac arrest may occur. In the pediatric intensive care unit (PICU) setting, the differential diagnosis of hyperkalemia may be extensive including increased potassium intake or administration, increased endogenous production, decreased renal excretion, and intracellular to extracellular shifts related to changes in acid-base status. We present a 4-month-old infant who developed hyperkalemia during the recovery phase of her PICU course for respiratory failure. A thorough investigation demonstrated that the hyperkalemia was most likely the result of the commonly used antibiotic, trimethoprim-sulfamethoxazole (Bactrim^®). Potential etiologies of hyperkalemia in the PICU patient are discussed and previous reports of hyperkalemia associated with trimethoprim-sulfamethoxazole presented.

Randomized Trial on the Effects of Dietary Potassium on Blood Pressure and Serum Potassium Levels in Adults with Chronic Kidney Disease

In the general population, an increased potassium (K) intake lowers blood pressure (BP). The effects of K have not been well-studied in individuals with chronic kidney disease (CKD). This randomized feeding trial with a 2-period crossover design compared the effects of diets containing 100 and 40 mmol K/day on BP in 29 adults with stage 3 CKD and treated or untreated systolic BP (SBP) 120–159 mmHg and diastolic BP (DBP) <100 mmHg. The primary outcome was 24 h ambulatory systolic BP. The higher-versus lower-K diet had no significant effect on 24 h SBP (−2.12 mm Hg; p = 0.16) and DBP (−0.70 mm Hg; p = 0.44). Corresponding differences in clinic BP were −4.21 mm Hg for SBP (p = 0.054) and −0.08 mm Hg for DBP (p = 0.94). On the higher-K diet, mean serum K increased by 0.21 mmol/L (p = 0.003) compared to the lower-K diet; two participants had confirmed hyperkalemia (serum K ≥ 5.5 mmol/L). In conclusion, a higher dietary intake of K did not lower 24 h SBP, while clinic SBP reduction was of borderline statistical significance. Additional trials are warranted to understand the health effects of increased K intake in individuals with CKD.

The effect of drone transport on the stability of biochemical, coagulation and hematological parameters in healthy individuals

Objectives

Transport of blood tubes is mainly by car or pneumatic transport. The transportation of blood tubes by drones is a novel approach for rapid transportation of blood tubes over long distances. However, limited data on the stability of biochemical, coagulation and hematological parameters is available after transport of blood tubes by drone.

Methods

To investigate the effect of drone transport on the stability of blood parameters, four test flights were performed. Blood was drawn from 20 healthy individuals and 39 of the most frequently measured blood parameters were compared between 4 groups; immediate measurement (control), late measurement, transport by car and transport by drone. Total Allowable Error (TAE) of the EFLM Biological Variation Database was used to determine the clinical relevance of significant differences.

Results

The majority of blood parameters were not affected by drone transport. Eight of the measured parameters showed significant differences between all the groups; glucose, phosphate, potassium, chloride, hemoglobin, platelet count, APTT and Lactate dehydrogenase (LD). A clinically relevant increase for LD after transport and a decrease for glucose values in time and after transport compared with the control group was shown.

Conclusions

Transportation of blood tubes from healthy individuals by drones has a limited clinically relevant effect. From the 39 investigated blood parameters only LD and glucose showed a clinically relevant effect.

Epidemiology, prognosis and management of potassium disorders in Covid-19

Coronavirus disease (Covid-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently the largest health crisis facing most countries. Several factors have been linked with a poor prognosis for this disease, including demographic factors, pre-existing comorbidities and laboratory parameters such as white blood cell count, D-dimer, C-reactive protein, albumin, lactate dehydrogenase, creatinine and electrolytes. Electrolyte abnormalities particularly potassium disorders are common among Covid-19 patients. Based on our pooled analysis, hypokalemia and hyperkalemia occur in 24.3% and 4.15% of Covid-19 patients, respectively. Potassium level deviation from the normal range may increase the chances of unfavorable outcomes and even death. Therefore, this article reviewed the epidemiology of potassium disorders and explained how hypokalemia and hyperkalemia are capable of deteriorating cardiac outcomes and the prognosis of Covid-19 for infected patients. The article finishes by highlighting some important considerations in the management of hypokalemia and hyperkalemia in these patients.

Update on management of hypokalemia and goals for the lower potassium level in patients with cardiovascular disease: A review in collaboration with the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy

Hypokalaemia is common in patients with cardiovascular disease. In this review, we emphasize the importance of tight potassium regulation in patients with cardiovascular disease based on findings from observational studies. To enhance the understanding, we also describe the mechanisms of potassium homeostasis maintenance, the most common causes of hypokalaemia and present strategies for monitoring and management of low potassium levels. We propose elevation of potassium in asymptomatic patients with lower normal concentrations and concurrent cardiovascular disease. These proposals are intended to assist clinicians until more evidence is available.

Management of hyperkalemia during treatment with mineralocorticoid receptor blockers: findings from esaxerenone

The nonsteroidal mineralocorticoid receptor (MR) blocker esaxerenone has demonstrated good antihypertensive activity in a variety of patients, including those with uncomplicated grade I-III hypertension, hypertension with moderate renal dysfunction, hypertension with type 2 diabetes mellitus with albuminuria, and hypertension associated with primary aldosteronism. Hyperkalemia has long been recognized as a potential side effect occurring during treatment with MR blockers, but there is a lack of understanding and guidance about the appropriate management of hyperkalemia during antihypertensive therapy with MR blockers, especially in regard to the newer agent esaxerenone. In this article, we first highlight risk factors for hyperkalemia, including advanced chronic kidney disease, diabetes mellitus, cardiovascular disease, age, and use of renin-angiotensin-aldosterone system inhibitors. Next, we examine approaches to prevention and management, including potassium monitoring, diet, and the use of appropriate therapeutic techniques. Finally, we summarize the currently available data for esaxerenone and hyperkalemia. Proper management of serum potassium is required to ensure safe clinical use of MR blockers, including awareness of at-risk patient groups, choosing appropriate dosages for therapy initiation and dosage titration, and monitoring of serum potassium during therapy. It is critical that physicians take such factors into consideration to optimize MR blocker therapy in patients with hypertension.

The Role of Using Red-Topped - Non-Additive-Containing - Collecting Tube in Diagnosing Pseudohyperkalemia in Chronic Lymphocytic Leukemia

Pseudohyperkalemia in the context of chronic lymphocytic leukemia (CLL) is becoming a common clinical presentation in our daily practice, yet the recognition and the overall approach to this condition remains a challenge as clinicians ponder on whether it's a true rise of serum potassium or not, weighing the risk-benefit ratio of giving the full anti-hyperkalemia measures, dreading the potential iatrogenic hypokalemia if it proves to be a pseudohyperkalemia instead.

Nano-Interstice Driven Powerless Blood Plasma Extraction in a Membrane Filter Integrated Microfluidic Device

Blood plasma is a source of biomarkers in blood and a simple, fast, and easy extraction method is highly required for point-of-care testing (POCT) applications. This paper proposes a membrane filter integrated microfluidic device to extract blood plasma from whole blood, without any external instrumentation. A commercially available membrane filter was integrated with a newly designed dual-cover microfluidic device to avoid leakage of the extracted plasma and remaining blood cells. Nano-interstices installed on both sides of the microfluidic channels actively draw the extracted plasma from the membrane. The developed device successfully supplied 20 μL of extracted plasma with a high extraction yield (~45%) in 16 min.

Accuracy of Hemolyzed Potassium Levels in the Emergency Department

Introduction

In the emergency department (ED), pseudohyperkalemia from hemolysis may indirectly harm patients by exposing them to increased length of stay, cost, and repeat blood draws. The need to repeat hemolyzed potassium specimens in low-risk patients has not been well studied. Our objective was to determine the rate of true hyperkalemia among low-risk, adult ED patients with hemolyzed potassium specimens.

Methods

We conducted this prospective observational study at two large (129,000 annual visits) academic EDs in the mid-Atlantic. Data were collected from June 2017–November 2017 as baseline data for planned departmental quality improvement and again from June 2018–November 2018. Inclusion criteria were an initial basic metabolic panel in the ED with a hemolyzed potassium level > 5.1 milliequivalents per liter that was repeated within 12 hours, age (≥18, and bicarbonate (HCO₃) > 20. Exclusion criteria were age > 65, glomerular filtration rate (GFR) < 60, creatine phosphokinase > 500, hematologic malignancy, taking potassium-sparing or angiotensin-acting agents, or treatment with potassium-lowering agents (albuterol, insulin, HCO₃, sodium polystyrene sulfonate, or potassium-excreting diuretic) prior to the repeat lab draw.

Results

Of 399 encounters with a hemolyzed, elevated potassium level in patients with GFR ≥ 60 and age > 18 that were repeated, we excluded 333 patients for age > 64, lab repeat > 12 hours, invalid identifiers, potassium-elevating or lowering medicines or hematologic malignancies.This left 66 encounters for review. There were no instances of hyperkalemia on the repeated, non-hemolyzed potassium levels, correlating to a true positive rate of 0% (95% confidence interval 0–6%). Median patient age was 46 (interquartile range [IQR] 34 – 56) years. Median hemolyzed potassium level was 5.8 (IQR 5.6 – 6.15) millimoles per liter (mmol/L), and median repeated potassium level was 3.9 (IQR 3.6 – 4.3) mmol/L. Median time between lab draws was 145 (IQR 87 – 262) minutes.

Conclusion

Of 66 patients who met our criteria, all had repeat non-hemolyzed potassiums within normal limits. The median of 145 minutes between lab draws suggests an opportunity to decrease the length of stay for these patients. Our results suggest that in adult patients < 65 with normal renal function, no hematologic malignancy, and not on a potassium-elevating medication, there is little to no risk of true hyperkalemia. Further studies should be done with a larger patient population and multicenter trials.

The potential role of the eGFR in differentiating between true and pseudohyperkalaemia

BACKGROUND

Differentiating between true and pseudohyperkalaemia is essential for patient management. The common causes of pseudohyperkalaemia include haemolysis, blood cell dyscrasias and EDTA contamination. One approach to differentiate between them is by checking the renal function, as it is believed that true hyperkalaemia is rare with normal function. This is logical, but there is limited published evidence to support it. The aim of this study was to investigate the potential role of the estimated glomerular filtration rate in differentiating true from pseudohyperkalaemia.

METHODS

GP serum potassium results >6.0 mmol/L from 1 January 2017 to 31 December 2017, with a repeat within seven days, were included. Entries were retrospectively classified as true or pseudohyperkalaemia based on the potassium reference change value and reference interval. If the initial sample had a full blood count, it was classified as normal/abnormal to remove blood cell dyscrasias. Different estimated glomerular filtration rate cut-points were used to determine the potential in differentiating true from pseudohyperkalaemia.

RESULTS

A total of 272 patients were included with potassium results >6.0 mmol/L, with 145 classified as pseudohyperkalaemia. At an estimated glomerular filtration rate of 90 ml/min/1.73 m², the negative predictive value was 81% (95% CI: 67-90%); this increased to 86% (95% CI: 66-95%) by removing patients with abnormal full blood counts. When only patients with an initial potassium ≥6.5 mmol/L were included (regardless of full blood count), at an estimated glomerular filtration rate of 90 ml/min/1.73 m², the negative predictive value was 100%. Lower negative predictive values were seen with decreasing estimated glomerular filtration rate cut-points.

CONCLUSION

Normal renal function was not associated with true hyperkalaemia, making the estimated glomerular filtration rate a useful tool in predicting true from pseudohyperkalaemia, especially for potassium results ≥6.5 mmol/L.

Pseudohyperkalemia in Serum and Plasma: The Phenomena and Its Clinical Implications

Hyperkalemia is a life threatening electrolyte derangement that must be recognized and treated quickly. Pseudohyperkalemia is defined as a difference between serum and plasma potassium concentration of more than 0.4 meq/L with serum values on the higher side when both the samples are obtained at the same time, remain at room temperature and are tested within 1 h of sample collection. Given the implication of basing medical decisions on falsely elevated potassium levels, timely identification of the entity of pseudohyperkalemia and differentiating it from true hyperkalemia becomes utmost important. Here we present a case report of a 36 year old female admitted with a provisional diagnosis of pyrexia of unknown origin with hepatosplenomegaly and anaemia under evaluation. During hospital stay her potassium levels in whole blood, serum and plasma reportedly differed significantly. An abnormal WBC count beyond assay range was reported and during subsequent investigations this lead to a peripheral smear being advised and diagnosis revealed chronic lymphoblastic leukaemia with blast crisis and 86% blast cells. In patients with leukocytosis and thrombocytosis, pseudohyperkalemia may exist in the absence of electrocardiogram changes or other clinical manifestations of true hyperkalemia thus leading to reevaluation of potassium values in serum, plasma and whole blood to arrive at the true picture.

Preliminary study on the correlation of plasma hemolysis index and potassium measurement of inpatient in the Biochemistry Laboratory of General Hospital Kuala Lumpur

Background: Potassium (K+) is the essential micronutrient and major intracellular fluid cation which involves in various cellular metabolism activities, maintaining fluid and electrolyte balance. Measurement of blood concentration in a medical laboratory has often encountered disturbances such as hemolysis, which may lead to the elevation in measurement and affects the medical diagnosis and treatment of the patient, conceivably fatal. Hemolysis can be decided using hemolysis index (H-index) through automation. Methods: In this study, H-index and concentration of fifty hospitalized patients (n=50) hemolysed blood samples were measured and correlated. Freezing-and-thaw method was used to hemolyse the blood samples. Different concentrations were diluted and analyzed using COBAS 8000 biochemistry analyser. Data were collected and analyzed using SPSS version 25. Results: Our findings showed significant mean differences, 0.001 (p ≤ 0.05) and strong positive linear relationship between two variables (H-index and ) (r=0.764, p ≤ 0.05). By applying calculated linear equation [y = 0.0048x + 5.146, = 0.5838], critical value of 6.0 mmol/l gives H-index of 178, H-index above 178 is suggested to be critical. Discussion and Conclusion: concentration increases in proportion to H-index. A greater degree of hemolysis causes more ions to be released into extracellular fluid, respectively. In conclusion, when H-index less than 178 in measurement and there is no analytical significance bias generated, the result is acceptable, whilst H-index with analyte variation between clinically significant bias range can be released with a comment regarding the potential of data alteration. Meanwhile, result with H-index exceeding the cut-offs should be suppressed and recollection of sample is required.

Technical note: Effect of delayed analysis of cooled lithium-heparinized whole blood on the stability of ionized calcium, ionized magnesium, sodium, potassium, chloride, glucose, and lactate in samples from dairy cows

The objectives of this study were to describe the stability of bovine whole-blood electrolytes, glucose, and lactate in samples collected in lithium heparin tubes and stored in thermoconductive modules immersed in ice water. A total of 99 Jersey cows (40 first-parity, 18 second-parity, and 41 third-parity or greater cows) from a commercial dairy farm in West Texas were enrolled between June and July 2018. Blood was collected from the jugular vein using a 60-mL polypropylene syringe and equally distributed into 5 spray-dried evacuated lithium heparin tubes. Baseline samples were analyzed within 90 s of collection using a benchtop blood gas analyzer. The remaining 4 tubes were stored in a thermoconductive, passive-temperature-regulating module inside a cooler with ice water. At 30 min and 2, 4, and 8 h post-collection, samples were removed from the temperature-regulating module, gently inverted for 10 s, and analyzed. Repeated-measures models were built to evaluate the effect of time on the stability of ionized Ca (iCa), ionized Mg (iMg), Na, K, Cl, glucose, and lactate. Most of the analytes investigated remained stable up to 8 h under ice water storage conditions before analysis, including iCa, iMg, Cl, glucose, and lactate. However, Na and K were significantly affected by delayed analysis: Na remained stable up to 4 h post-collection, but K was not stable starting at 2 h post-collection. The results of this study are useful in helping future researchers and consultants to recognize acceptable time delays between whole blood collection and processing or analysis for electrolytes, glucose, and lactate.

Plasma potassium ranges associated with mortality across stages of chronic kidney disease: the Stockholm CREAtinine Measurements (SCREAM) project

Background

Small-scale studies suggest that hyperkalaemia is a less threatening condition in chronic kidney disease (CKD), arguing adaptation/tolerance to potassium (K⁺) retention. This study formally evaluates this hypothesis by estimating the distribution of plasma K⁺ and its association with mortality across CKD stages.

Methods

This observational study included all patients undergoing plasma K⁺ testing in Stockholm during 2006–11. We randomly selected one K⁺ measurement per patient and constructed a cross-sectional cohort with mortality follow-up. Covariates included demographics, comorbidities, medications and estimated glomerular filtration rate (eGFR). We estimated K⁺ distribution and defined K⁺ ranges associated with 90-, 180- and 365-day mortality.

Results

Included were 831 760 participants, of which 70 403 (8.5%) had CKD G3 (eGFR <60–30 mL/min) and 8594 (1.1%) had CKD G4–G5 (eGFR <30 mL/min). About 66 317 deaths occurred within a year. Adjusted plasma K⁺ increased across worse CKD stages: from median 3.98 (95% confidence interval 3.49–4.59) for eGFR >90 to 4.43 (3.22–5.65) mmol/L for eGFR ≤15 mL/min/1.73 m². The association between K⁺ and mortality was U-shaped, but it flattened at lower eGFR strata and shifted upwards. For instance, the range where the 90-day mortality risk increased by no more than 100% was 3.45–4.94 mmol/L in eGFR >60 mL/min, but was 3.36–5.18  in G3 and 3.26–5.53 mmol/L in G4–G5. In conclusion, CKD stage modifies K⁺ distribution and the ranges that predict mortality in the community.

Conclusion

Although this study supports the view that hyperkalaemia is better tolerated with worse CKD, it challenges the current use of a single optimal K⁺ range for all patients.

The Impact of Undetected In Vitro Hemolysis or Sample Contamination on Patient Care and Outcomes in Point-of-Care Testing: A Retrospective Study

BACKGROUND

Point-of-care (POC) testing is an integral diagnostic component in clinical settings like the emergency department (ED). However, most POC testing devices are unable to detect endogenous interferents such as hemolysis, which typically occurs during sample collection and handling and can falsely increase measured potassium (pseudohyperkalemia), a phenomenon we hypothesized may significantly impact patient care.

METHODS

In this retrospective study, we evaluated 100 unique admissions to the Oregon Health & Science University ED, presenting with elevated potassium measured at the POC. To evaluate whether in vitro hemolysis had occurred, POC test results were compared to repeat testing of the original specimen, or other specimens tested within 90 minutes in the Core laboratory. Review of associated Electronic Health Records determined whether elevated potassium initially measured using the POC analyzer was real, or due to in vitro hemolysis or contamination, and whether pseudohyperkalemia impacted patient management or care.

RESULTS

Of the 100 admissions with hyperkalemia measured using a POC analyzer, 40% were found to have pseudohyperkalemia due to hemolysis or contamination. Of these 40 patients, 6 experienced repeated testing, and an additional 5 were noted to have altered patient management, specifically due to pseudohyperkalemia.

CONCLUSIONS

This study demonstrates the incidence of in vitro hemolysis, which is unknown to the POC operator, is high in patients who show an elevated potassium as measured at the POC. Furthermore, in vitro hemolysis can significantly impact patient management, suggesting that minimizing the incidence of unrecognized hemolysis will benefit hospital efficiency, decrease waste, and improve patient care.

Potassium infusion increases the likelihood of conversion of recent-onset atrial fibrillation-A single-blinded, randomized clinical trial

BACKGROUND

The optimal antiarrhythmic management of recent-onset atrial fibrillation (ROAF) or atrial flutter is controversial and there is a considerable variability in clinical treatment strategies. It is not known if potassium infusion has the potential to convert ROAF or atrial flutter to sinus rhythm (SR). Therefore, we aimed to investigate if patients with ROAF or atrial flutter and plasma-potassium levels ≤4.0 mmol/L have increased probability to convert to SR if the plasma-potassium level is increased towards the upper reference range (4.1-5.0 mmol/L).

METHODS

In a placebo-controlled, single-blinded trial, patients with ROAF or atrial flutter and plasma-potassium ≤4.0 mmol/L presenting between April 2013 and November 2017 were randomized to receive potassium chloride (KCl) infusion (n = 60) or placebo (n = 53). Patients in the KCl group received infusions at one of three different rates: 9.4 mmol/h (n = 11), 12 mmol/h (n = 19), or 15 mmol/h (n = 30).

RESULTS

There was no statistical difference in the number of conversions to SR between the KCl group and placebo [logrank test, P = .29; hazard ratio (HR) 1.20 (CI 0.72-1.98)]. However, KCl-infused patients who achieved an above-median hourly increase in plasma-potassium (>0.047 mmol/h) exhibited a significantly higher conversion rate compared with placebo [logrank P = .002; HR 2.40 (CI 1.36-4.21)] and KCl patients with below-median change in plasma-potassium [logrank P < .001; HR 4.41 (CI 2.07-9.40)]. Due to pain at the infusion site, the infusion was prematurely terminated in 10 patients (17%).

CONCLUSIONS

Although increasing plasma-potassium levels did not significantly augment conversion of ROAF or atrial flutter to SR in patients with potassium levels in the lower-normal range, our results indicate that this treatment may be effective when a rapid increase in potassium concentration is tolerated and achieved.

Potassium disturbance associated with an inpatient childhood asthma pathway

Background

Paediatric asthma exacerbations in Alberta are treated via standardized order sets known as the Alberta Acute Childhood Asthma Pathway (ACAP). This pathway is utilized in paediatric tertiary hospitals and in remote and rural locations. Incidence, magnitude, and risk factors for hypokalemia in inpatients receiving salbutamol for asthma exacerbations via this pathway are presently unknown.

Objective

Establish incidence, magnitude, and risk factors for hypokalemia associated with salbutamol therapy as directed by a paediatric asthma pathway.

Methods

Retrospective cohort study using visit-level electronic medical data. Inpatients aged <18 years old receiving salbutamol via the ACAP with at least one potassium level were included. Hypokalemia was defined as mild (3.0 ≤ [K⁺] < 3.5 mEq/L), moderate (2.5 ≤ [K⁺] < 3.0 mEq/L), or severe ([K⁺] < 2.5 mEq/L), as measured in serum or blood gas. Binomial logistic regression was utilized to examine risk factors for hypokalemia, route of administration, location of lowest [K⁺], nil per os (NPO) status during admission, potassium supplementation, gender, and age.

Results

There were 821 patients screened for analysis and 433 patients were analyzed after exclusions. There was an incidence of hypokalemia of 38.8%. Of patients experiencing hypokalemia, 71.4% were mild, 25.6% moderate, and 3.0% severe. Risk factors included nebulized salbutamol, patient location (emergency department or paediatric intensive care unit), and age (>5 years) although these risk factors may actually represent patients receiving higher doses of salbutamol.

Conclusions

The majority of the 38.8% of children experiencing hypokalemia associated with the ACAP were mild. Routine monitoring of potassium status in children receiving salbutamol per standardized pathway is recommended for children with described risk factors, and ideally within the first 12 hours of presentation.

Blood sample quality

Several lines of evidence now confirm that the vast majority of errors in laboratory medicine occur in the extra-analytical phases of the total testing processing, especially in the preanalytical phase. Most importantly, the collection of unsuitable specimens for testing (either due to inappropriate volume or quality) is by far the most frequent source of all laboratory errors, thus calling for urgent strategies for improving blood sample quality and managing data potentially generated measuring unsuitable specimens. A comprehensive overview of scientific literature leads us to conclude that hemolyzed samples are the most frequent cause of specimen non-conformity in clinical laboratories (40-70%), followed by insufficient or inappropriate sample volume (10-20%), biological samples collected in the wrong container (5-15%) and undue clotting (5-10%). Less frequent causes of impaired sample quality include contamination by infusion fluids (i.e. most often saline or glucose solutions), cross-contamination of blood tubes additives, inappropriate sample storage conditions or repeated freezing-thawing cycles. Therefore, this article is aimed to summarize the current evidence about the most frequent types of unsuitable blood samples, along with tentative recommendations on how to prevent or manage these preanalytical non-conformities.