Serum Total Carbon Dioxide Research Articles

8226 A Diagnostic Challenge: Factitious Hypobicarbonatemia in Severe Hypertriglyceridemia

Abstract Disclosure: U. Rafat: None. S. Azmat: None. M. Siddiqui: None. R. Alshantti: None. D. Kircheva: None. V. Trendafilova: None. Background: Serum CO2 levels measured by a chemistry analyzer usually correlate with calculated bicarbonate levels on an ABG. There are some instances however, when this is not the case. Severe hypertriglyceridemia can cause serum bicarbonate levels to appear falsely low on metabolic panel. Clinical Case: A 48-year-old man was referred to Endocrinology Clinic for evaluation of hypogonadism and severe hypertriglyceridemia. Routine labs revealed a plasma CO2 of 11 mmol/L (20-31). Na was 133 mmol/L (136-145), K was 4.4 mmol/L (3.5-4.7), Chloride was 101 mmol/L (98-109) and anion gap was 25 (8-20) measured using a Siemens Vista enzymatic chemistry analyzer. His triglycerides were > 1100 mg/dL (0-150), above upper detection limits of the analyzer. The patient reported fatigue and mild abdominal pain. He was admitted to the hospital for further evaluation. His lipase was 41 U/L (12-73), lactic acid 1.2 mmol/L (0.50-2.20). ABG showed pH of 7.41, HCO3 of 26.6 mmol/L (22-29), and anion gap of 7 (10-20). The patient was well-appearing with normal vital signs and normal physical exam. He was made NPO and started on pravastatin, fenofibrate and fish oil. Once his triglycerides were < 1000 mg/dL, he was started on a very low-fat, low-carbohydrate diet. The CO2 level on BMP normalized on day 3 of hospitalization, when triglycerides measured 1010 mg/dL. No other treatment was given for the low CO2 levels. It does not appear that other lab indices were significantly affected by the hypertriglyceridemia. Review of Literature: A BMP measures serum total carbon dioxide using a chemistry analyzer using either an enzymatic/spectro-photometric method, or an electrode-based method; an ABG sample calculates plasma bicarbonate with the Henderson-Hasselbach equation, using the pH and partial pressure of pCO2 in the sample. Enzymatic analyzers measure CO2 using spectrophotometry and decrease in light absorbance is proportional to the sample’s CO2 levels. It is postulated that severely high triglycerides can interfere with this reaction and cause spuriously low CO2 levels, a phenomenon called pseudohypobicarbonatemia. One proposed mechanism for interference with the enzymatic assay method is turbidity causing a falsely low measured CO2 level. Verghese et al found that the severity of the CO2 measurement error positively correlates with the severity of triglyceride elevation. Conclusion: Awareness of the phenomenon of hypertriglyceridemia-induced pseudohypobicarbonatemia can prevent misdiagnosis or delays in diagnosis, as well as unwarranted testing and treatment. Presentation: 6/3/2024

Effects of Hemp-Derived Cannabidiol Supplementation on Blood Variables, Carcass Characteristics, and Meat Quality of Goats.

Stress experienced by animals during pre-mortem management handling significantly affects both their welfare and the quality of the meat produced. Using hemp-derived CBD may offer several benefits in alleviating this issue. In this study, we investigated the effects of hemp-derived CBD supplementation on blood variables, growth performance, carcass characteristics, and meat quality in goats. Sixteen crossbred Boer goats were divided into four groups receiving a basal diet supplemented with 0 (control), 0.1, 0.2, or 0.3 mL CBD/30 kg body weight over 90 days. Although growth, carcass characteristics, and pH remained unaffected, CBD supplementation influenced several blood variables. Specifically, dietary CBD at 0.1-0.3 mL increased white blood cell (WBC) counts, while 0.3 mL CBD increased serum total protein, globulin, sodium, and carbon dioxide levels, potentially affecting protein metabolism and electrolyte balance. Over time, significant changes were noted in hematological profiles, kidney markers, protein profiles, and some electrolytes, indicating physiological adaptations. Regarding meat quality, supplementation with 0.2-0.3 mL of CBD linearly improved color redness and stability; moreover, CBD supplementation improved tenderness and textural properties, resulting in a softer meat texture. However, analysis using an E-nose indicated increased ammonia and organic solvent vapors in meat from the higher CBD groups. This study concluded that CBD supplementation up to 0.3 mL of CBD/30 kg body weight beneficially modulated blood biomarkers, meat color, and tenderness without adverse impacts on growth or carcass characteristics in goats.

Associations of the Serum Total Carbon Dioxide Level with Long-Term Clinical Outcomes in Sepsis Survivors.

Sepsis is characterized by a dysregulated host response to infection that leads to multiple organ dysfunction and often complicated with metabolic acidosis. However, the associations between serum total carbon dioxide level (TCO2) and long-term clinical outcomes in sepsis survivors remains unknown. A total of 7212 sepsis survivors aged ≥ 20years who were discharged from January 1, 2008 to December31, 2018 were included in our analyses. The sepsis survivors were further divided into high TCO2 (≥18mmol/L) and low TCO2 (< 18mmol/L) groups, comprising 5023 and 2189 patients, respectively. The following outcomes of interest were included: all-cause mortality, myocardial infarction, ischemic stroke, hospitalization for heart failure, ventricular arrhythmia, and end-stage renal disease (ESRD). After propensity score matching, the low TCO2 group was at higher risks of all-cause mortality (hazard ratio [HR] 1.28, 95% confidence interval [95%CI] 1.18-1.39), myocardial infarction (HR 1.83, 95%CI 1.39-2.43), and ESRD (HR 1.38, 95%CI 1.16-1.64) than the high TCO2 group. The results remained similar after considering death as a competing risk. Patients discharged from hospitalization for sepsis have higher risks of worse long-term clinical outcomes. Physicians may need to pay more attention to sepsis survivors whose TCO2 was low.

Utilization of Partial Carbon Dioxide and Serum Total Carbon Dioxide Gradients in the Emergency Care of Acute Decompensated Heart Failure

Utilization of Partial Carbon Dioxide and Serum Total Carbon Dioxide Gradients in the Emergency Care of Acute Decompensated Heart Failure

Association of Pre-ESRD Serum Bicarbonate with Post-ESRD Mortality in Patients with Incident ESRD

Background: Serum bicarbonate or total carbon dioxide (CO₂) concentrations decline as chronic kidney disease (CKD) progresses and rise after dialysis initiation. While metabolic acidosis accelerates the progression of CKD and is associated with higher mortality among patients with end stage renal disease (ESRD), there are scarce data on the association of CO₂ concentrations before ESRD transition with post-ESRD mortality. Methods: A historical cohort from the Transition of Care in CKD (TC-CKD) study includes 85,505 veterans who transitioned to ESRD from October 1, 2007, through March 31, 2014. After 1,958 patients without follow-up data, 3 patients with missing date of birth, and 50,889 patients without CO₂ 6 months prior to ESRD transition were excluded, the study population includes 32,655 patients. Associations between CO₂ concentrations averaged over the last 6 months and its rate of decline during the 12 months prior to ESRD transition and post-ESRD all-cause, cardiovascular (CV), and non-CV mortality were examined by using hierarchical adjustment with Cox regression models. Results: The cohort was on average 68 ± 11 years old and included 29% Black veterans. Baseline concentrations of CO₂ were 23 ± 4 mEq/L, and median (interquartile range) change in CO₂ were −1.8 [−3.4, −0.2] mEq/L/year. High (≥28 mEq/L) and low (<18 mEq/L) CO₂ concentrations showed higher adjusted mortality risk while there was no clear trend in the middle range. Consistent associations were observed irrespective of sodium bicarbonate use. There was also a U-shaped association between the change in CO₂ and all-cause, CV, and non-CV mortality with the lowest risk approximately at −2.0 and 0.0 mEq/L/year among sodium bicarbonate nonusers and users, respectively, and the highest mortality was among patients with decline in CO₂ >4 mEq/L/year. Conclusion: Both high and low pre-ESRD CO₂ levels (≥28 and <18 mEq/L) during 6 months prior to dialysis transition and rate of CO₂ decline >4 mEq/L/year during 1 year before dialysis initiation were associated with greater post-ESRD all-cause, CV, and non-CV mortality. Further studies are needed to determine the optimal management of CO₂ in patients with advanced CKD stages transitioning to ESRD.

Relationship Between Serum Total Carbon Dioxide Concentration and Bicarbonate Concentration in Patients Undergoing Peritoneal Dialysis.

BackgroundFew studies have assessed the relationship between serum total carbon dioxide (CO2) and bicarbonate ion (HCO3−) concentration in patients undergoing peritoneal dialysis. We determined the agreement between serum total CO2 and HCO3− concentration and the diagnostic accuracy of serum total CO2 for the prediction of low (HCO3− <24 mEq/L) and high (HCO3− ≥24 mEq/L) bicarbonate concentrations in patients on peritoneal dialysis.MethodsWe collected 245 samples of venous blood from 51 patients on peritoneal dialysis. Independent factors that correlated with the HCO3− concentration were analyzed using multiple linear regression analysis. The diagnostic accuracy of serum total CO2 was evaluated by receiver operating characteristic (ROC) curve analysis and a 2×2 table. Agreement between serum total CO2 and HCO3− concentration was assessed by Bland-Altman analysis.ResultsSerum total CO2 was independently correlated with HCO3− concentration (β = 0.354, p < 0.001). The area under the curve of serum total CO2 for the identification of low and high bicarbonate concentrations was 0.909. The diagnostic accuracy of serum total CO2 for the prediction of low and high bicarbonate concentrations was: sensitivity, 91.5%; specificity, 74.7%; positive predictive value, 53.5%; negative predictive value, 96.5%; and accuracy, 78.8%. Bland-Altman analysis showed a moderate agreement between serum total CO2 and HCO3− concentration.ConclusionSerum total CO2 correlated closely with the HCO3− concentration in patients undergoing peritoneal dialysis. Serum total CO2 might be useful for predicting low and high bicarbonate in peritoneal dialysis patients.

Relationship between serum total carbon dioxide concentration and bicarbonate concentration in patients undergoing hemodialysis

BackgroundFew studies have investigated the relationship between serum total carbon dioxide (CO2) concentration and bicarbonate ion (HCO3-) concentration in patients undergoing hemodialysis. We determined the agreement and discrepancy between serum total CO2 and HCO3- concentrations and the diagnostic accuracy of serum total CO2 for the prediction of low (HCO3- < 24 mEq/L) and high (HCO3- ≥ 24 mEq/L) bicarbonate concentrations in hemodialysis patients.MethodsOne hundred forty-nine arteriovenous blood samples from 84 hemodialysis patients were studied. Multiple linear regression analysis was used to determine factors correlated with HCO3- concentration. Diagnostic accuracy of serum total CO2 was evaluated using receiver operating characteristic curve analysis and a 2 × 2 table. Agreement between serum total CO2 and HCO3- concentrations was assessed using Bland-Altman analysis.ResultsSerum total CO2 concentration was closely correlated with HCO3- concentration (β = 0.858, P < 0.001). Area under the curve of serum total CO2 for the identification of low and high bicarbonate concentrations was 0.989. Use of serum total CO2 to predict low and high bicarbonate concentrations had a sensitivity of 100%, specificity of 50.0%, positive predictive value of 96.5%, negative predictive value of 100%, and accuracy of 96.6%. Bland-Altman analysis showed moderate agreement between serum total CO2 and HCO3- concentrations. Discrepancies between HCO3- and serum total CO2 concentrations (serum total CO2 - HCO3- ≤ -1) were observed in 89 samples.ConclusionSerum total CO2 concentration is closely correlated with HCO3- concentration in hemodialysis patients. However, there is a non-negligible discrepancy between serum total CO2 and HCO3- concentrations.

Effect of High Atmospheric Carbon Dioxide Concentrations on the Serum Total Carbon Dioxide Measurement

Background: Serum total carbon dioxide (TCO₂) measurements are easily affected by numerous factors. Whether an irregularly high atmospheric CO₂ concentration affects the TCO₂ measurement remains unclear. Materials and Methods: In Somdech Phra Debaratana Medical Center laboratory (SDMC) and the main building laboratory (Building 1) located within Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, the repeated TCO₂ measurements using an enzymatic assay in three levels of human based control material were performed every two hours, over a one-day period. TCO₂ in a total of 150 patient sera were measured. Simultaneously, atmospheric CO₂ levels were determined. Results: Atmospheric CO₂ levels in SDMC and Building 1, ranged from 763 to 1,560 ppm and 602 to 787 ppm, respectively. Repeated TCO₂ measurements for SDMC, the measured TCO₂ concentrations of all control materials clearly increased between 10:00 a.m. and 4:00 p.m., with the peak at 2:00 p.m., which was related to an increase in the atmospheric CO₂ concentration. By contrast, in Building 1, the measurements were considerably stable. Moreover, considering patient data (n=12,042), the estimate median TCO₂ concentration in SDMC was likely to increase between 10:00 a.m. to 4:00 p.m. as well. The association between the bias (y), difference TCO₂ concentration obtained between the SDMC and the Building 1, and the increasing atmospheric CO₂ (x) was y = 0.0038x – 0.016, R²=0.6813. Using regression equations, TCO₂ level increased by approximately 0.4 mmol/L for every 100 ppm of CO₂ increase in atmosphere. Conclusion: High atmospheric CO₂ concentrations can result in falsely high TCO₂ values, which may lead to markedly wrong interpretations, especially in patients with a tendency to have low TCO₂ concentrations. Keywords: Serum total carbon dioxide, Atmospheric carbon dioxide, Acid-base disorder

Optimizing serum total carbon dioxide concentration during short and nocturnal frequent hemodialysis using lactate as dialysate buffer base.

Definitive clinical studies to determine the optimal dialysate lactate concentration to prescribe during frequent hemodialysis when using the NxStage System One dialysis delivery system at low dialysate flow rates have not been reported. We used clinical data from patients who transferred from in-center thrice-weekly hemodialysis (ICHD) to daily home hemodialysis using the NxStage System One and the H+ mobilization model to calculate acid generation rates in patient sub-groups during the FREEDOM study. Assuming those acid generation rates were representative, we then predicted using the H+ mobilization model the effect of using dialysate lactate concentrations of 40 and 45 mEq/L on predialysis serum total carbon dioxide (tCO2 ) concentrations in patients who transfer from ICHD to short and nocturnal frequent hemodialysis prescriptions used in current clinical practice; the prescriptions evaluated varied by treatment frequency, dialysate volume per treatment, and treatment times. With frequencies of four to six treatments per week and treatment times of 170 to 210 minutes per treatment, the effect of dialysate lactate concentration was primarily dependent on weekly dialysate volume. For weekly dialysate volumes of 150 to 160 L per week, use of dialysate lactate concentrations of 45 mEq/L, but not 40 mEq/L, resulted in an increase of predialysis serum tCO2 concentration. When longer treatment times typical of nocturnal frequent hemodialysis were evaluated, model predictions showed that the use of dialysate lactate concentration of 45 mEq/L may not be appropriate for many patients because of excessive increases in predialysis serum tCO2 concentration. Reducing dialysate volume from 60 to 30 L may limit the increase in predialysis serum tCO2 concentration when patients transfer from ICHD to nocturnal frequent hemodialysis. Predictions from the H+ mobilization model show that dialysate lactate concentration and weekly dialysate volume are the primary prescription parameters for optimizing predialysis serum tCO2 concentration during short and nocturnal frequent hemodialysis.

Serum total carbon dioxide as a prognostic factor for 28-day mortality in patients with sepsis.

Metabolic acidosis is commonly associated with the disease severity in patients with sepsis or septic shock. This study was performed to investigate the association between serum total carbon dioxide (TCO2) concentration and 28-day mortality in patients with sepsis. This study was a multicenter retrospective cohort study of patients with sepsis or septic shock. The relationships between serum TCO2 and 28-day mortality, bicarbonate, pH, lactate, and anion gap were determined with cubic spline curves. The patients were divided into four groups according to their serum TCO2 concentration: Group I (TCO2>20mmol/l), Group II (15<TCO2≤20mg/dl), Group III (10<TCO2≤15mmol/l), and Group IV (TCO2≤10mmol/l). A total of 3168 patients were included in the analysis, and the overall mortality rate was 24.1%. Serum TCO2 concentrations below 20mmol/l showed an almost linear correlation with mortality as well as with lactate, bicarbonate, and pH. The 28-day mortality rates of Group I, II, III, and IV were 18.3%, 23.6%, 32.6%, and 50.0%, respectively (p<.001). In Multivariable Cox proportional hazard regression analysis, the groups with lower serum TCO2 concentrations had a higher risk of 28-day mortality compared with Group I: Group II (Hazard ratio (HR), 1.35; 95% confidence interval (CI), 1.11-1.64), Group III (HR, 1.74; 95% CI, 1.37-2.21), and Group IV (HR, 2.72; 95% CI, 2.03-3.64). Serum TCO2 concentrations of 20mmol/l or less were associated with 28-day mortality in patients with sepsis.

Early-start and conventional-start peritoneal dialysis: a Chinese cohort study on outcome

Background Early-start peritoneal dialysis (PD) is an effective option for patients need unplanned dialysis. However, there are few studies on the long-term prognosis of early-start PD patients. Methods In this retrospective study, 635 eligible patients from 1 March 1996 to 30 September 2016 were included, and divided into three groups according to the duration of break-in period: 3 days or less, 4–13 days and more than 14 days. Patients started PD within 2 weeks and after 2 weeks were defined as early-start and conventional-start, respectively. The primary outcome was all-cause mortality, and the secondary outcome measures were peritonitis free survival and technical survival. Mechanical and infectious complications in the first 180 days were also analyzed. Results Early-start PD patients were more likely to have higher serum total carbon dioxide and creatinine levels and lower serum albumin, Kt/v, creatinine clearance (Ccr) and residual glomerular filtration rate (rGFR) levels at the start of PD. The median follow-up period was 30 months (interquartile range, 13-53 months). A worse survival was observed in the early-start group than that in the conventional-start group (p < 0.001), even adjustment for the covariates (HR 1.549, 95%CI 1.104–2.173, p = 0.011). In the subgroup analysis, in patients commencing PD after 2006 early-start and conventional-start PD patients had comparable survival. No differences were observed in the rate of infectious and mechanical complications, peritonitis-free survival and technique survival between early-start and conventional-start PD patients. Conclusions Early-start PD could be a safe and effective strategy for patients needing unplanned dialysis initiation with the progress of technology on PD.

Approximation of bicarbonate concentration using serum total carbon dioxide concentration in patients with non-dialysis chronic kidney disease.

BackgroundWe investigated the relationship between serum total carbon dioxide (CO2) and bicarbonate ion (HCO3−) concentrations in pre-dialysis chronic kidney disease (CKD) patients and devised a formula for predicting low bicarbonate (HCO3−< 24 mmol/L) and high bicarbonate (HCO3− ≥ 24 mmol/L) using clinical parameters.MethodsIn total, 305 samples of venous blood collected from 207 pre-dialysis patients assessed by CKD stage (G1 + G2, 46; G3, 50; G4, 51; G5, 60) were investigated. The relationship between serum total CO2 and HCO3− concentrations was analyzed using Pearson’s correlation coefficient. An approximation formula was developed using clinical parameters correlated independently with HCO3− concentration. Diagnostic accuracy of serum total CO2 and the approximation formula was evaluated by receiver operating characteristic curve analysis and a 2 × 2 table.ResultsSerum total CO2 correlated strongly with HCO3− concentration (r = 0.91; P < 0.001). The following approximation formula was obtained by a multiple linear regression analysis: HCO3− (mmol/L) = total CO2 − 0.5 × albumin − 0.1 × chloride − 0.01 × (estimated glomerular filtration rate + blood glucose) + 15. The areas under the curves of serum total CO2 and the approximation formula for detection of low bicarbonate and high bicarbonate were 0.981, 0.996, 0.993, and 1.000, respectively. This formula had superior diagnostic accuracy compared with that of serum total CO2 (86.6% vs. 81.3%).ConclusionSerum total CO2 correlated strongly with HCO3− concentration in pre-dialysis CKD patients. An approximation formula including serum total CO2 showed superior diagnostic accuracy for low and high bicarbonate compared with serum total CO2.

Effects of high atmospheric CO2 on serum total carbon-dioxide determination

Effects of high atmospheric CO2 on serum total carbon-dioxide determination

Comparison of measured Serum Total Carbon Dioxide with calculated Bicarbonate calculated from Arterial Blood Gas Analysis

ABSTRACTIntroductionMeasured total carbon dioxide (TCO2) from venous sample and calculated bicarbonate from arterial blood gas (ABG) have shown good agreement in some studies, while conflicting results have been obtained in few other studies. The objective of this study is to compare and assess the degree of agreement between the measured TCO2and calculated bicarbonate and also whether they can be used interchangeably in our laboratory.Materials and methodsWe prospectively analyzed 89 ABG samples requested for calculated bicarbonate and then measured TCO2from venous blood samples drawn simultaneously from the same participants between November 2016 and April 2017.ResultsMeasured TCO2results ranged from 5.7 to 39.9 mmol/L (mean 23.45 mmol/L), while calculated bicarbonate ranged from 9 to 40 mmol/L (mean 24.36 mmol/L). The values of TCO2and bicarbonate correlated well (r = 0.95, p &lt; 0.001), with the correlation given by the equation, y = 0.884x+ 3.605. The bias obtained was —0.9 mmol/L and the standard deviation (SD) was 1.62 mmol/L. The limits of agreement (LOA) were —4.1 to 2.3 mmol/L, with a span of 6.4 mmol/L. Out of the 89 values, 85 (95.05%) were within the LOA.ConclusionIn majority of the cases, the calculated bicarbonate concentration from ABG showed a good correlation to the measured venous TCO2concentration. Despite this excellent correlation, TCO2did not show good agreement with calculated bicarbonate when Story and Poustie's criteria were applied, especially in cases of bicarbonate less than 20 mmol/L. Hence, clinicians should be aware of this discrepancy and be cautious when using measured TCO2and calculated bicarbonate interchangeably in the assessment and management of acid—base disorders, especially in patients with metabolic acidosis.How to cite this articleMohan T, Kumar BV. Comparison of measured Serum Total Carbon Dioxide with calculated Bicarbonate calculated from Arterial Blood Gas Analysis. Indian J Med Biochem 2017;21(2):76-80.

Perioperative Concerns for Profound Metabolic Alkalosis During Kidney Transplantation: A Case Report

IntroductionProfound metabolic alkalosis is an uncommon consideration for the anesthetic management of kidney transplantation. Serum total carbon dioxide content and complex electrolyte abnormalities might be important diagnostic clues for the presence of metabolic alkalosis in the absence of arterial blood gas analysis.Case PresentationA 34-year-old female visited Gachon University Gil Medical Center, Incheon, South Korea during year 2015. She experienced aggravated renal function due to chronic hypokalemia and severe hypochloremic metabolic alkalosis, induced by laxative abuse, and underwent ABO incompatible kidney transplantation. Serum total carbon dioxide content remained high (about 60 mEq/L) over eight months of monthly follow-up prior to kidney transplantation.ConclusionsThe authors described their anesthetic experience of profound metabolic alkalosis with complex electrolyte abnormalities and provided a review of relevant literature.

Pseudohypobicarbonatemia Caused by an Endogenous Assay Interferent: A New Entity

Serum total carbon dioxide, measured using a chemistry analyzer, and gas panel-derived plasma bicarbonate, calculated from the pH and partial pressure of carbon dioxide, often are used interchangeably for clinical purposes. When they disagree, there is a tendency to accept total carbon dioxide and discredit gas panel-derived plasma bicarbonate values. We report a patient who, during a 5-month hospitalization, had persistently low total carbon dioxide levels (12.4 ± 2.7 [standard deviation] mEq/L [12.4 ± 2.7 mmol/L]), measured using an enzymatic/photometric assay, and a high anion gap (19.2 ± 3.1 mEq/L [19.2 ± 3.1 mmol/L]), suggesting high-anion-gap metabolic acidosis, but who had gas panel-derived plasma bicarbonate (24.0 ± 0.9 mEq/L [24.0 ± 0.9 mmol/L]) and arterial pH values in the reference range. Organic anion levels in blood and urine were unremarkable. Negative interference with the enzymatic assay by the patient's serum was shown by the findings that total carbon dioxide level was 7.0 ± 0.1 mEq/L (7.0 ± 0.1 mmol/L) higher when measured using the electrode-based method than using the enzymatic method (P < 0.01), and the patient's serum, but not control serum, altered the reaction kinetics of the enzymatic assay by producing turbidity, resulting in an initial increase in absorbance and a falsely low total carbon dioxide value. The turbidity may have resulted from precipitation of 1 of 2 paraproteins in the patient's serum or an endogenous antibody binding with an animal protein included in the assay reagents. In summary, a discrepancy between total carbon dioxide level measured using an enzymatic assay and gas panel-derived plasma bicarbonate level was found to be the result of turbidity caused by an endogenous interferent with the total carbon dioxide assay, a novel artifact. When total carbon dioxide and gas panel-derived plasma bicarbonate values disagree, measurement error in total carbon dioxide level should be considered.

Abnormalities of serum potassium concentration in dialysis-associated hyperglycemia and their correction with insulin: a unique clinical/physiologic exercise in internal potassium balance

The absence of significant losses of potassium in the urine makes dialysis-associated hyperglycemia (DH) a model for the study of the internal potassium balance. Studies of DH have revealed that hyperkalemia is frequent at presentation, insulin infusion is usually the only treatment required, and the magnitude of the decrease in serum potassium concentration (K(+)) during treatment of DH with insulin depends on the starting serum K(+) level, the decreases in serum glucose concentration and tonicity, and the increase in serum total carbon dioxide level. We present an analysis of these findings based on previously studied actions of insulin. Calculations of transcellular potassium shifts based on the combined effects of insulin-the increase in the electrical potential differences (hyperpolarization) of the cell membranes and the correction of the hyperglycemic intracellular dehydration through decrease in serum glucose concentration-produced quantitative predictions of the decrease in serum K(+) similar to the reported changes in serum K(+) during treatment of DH with insulin. The lessons from analyzing serum K(+) changes during treatment of DH with insulin are applicable to other conditions where internal potassium balance is called upon to protect serum K(+), such as the postprandial state. The main questions related to internal potassium balance in DH that await clarification include the structure and function of cell membrane potassium channels, the effect of insulin on these channels, and the mechanisms of feedforward potassium regulation.

Abnormalities of serum potassium concentration in dialysis-associated hyperglycemia and their correction with insulin: review of published reports

The main difference between dialysis-associated hyperglycemia (DH) and diabetic ketoacidosis (DKA) or nonketotic hyperglycemia (NKH) occurring in patients with preserved renal function is the absence of osmotic diuresis in DH, which eliminates the need for large fluid and solute (including potassium) replacement. We analyzed published reports of serum potassium (K(+)) abnormalities and their treatment in DH. Hyperkalemia was often present at presentation of DH with higher frequency and severity than in hyperglycemic syndromes in patients with preserved renal function. The frequency and severity of hyperkalemia were higher in DH episodes with DKA than those with NKH in both hemodialysis and peritoneal dialysis. For DKA, the frequency and severity of hyperkalemia were similar in hemodialysis and peritoneal dialysis. For NKH, hyperkalemia was more severe and frequent in hemodialysis than in peritoneal dialysis. Insulin infusion corrected the hyperkalemia of DH in most cases. Additional measures for the management of hyperkalemia or modest potassium infusions for hypokalemia were needed in a few DH episodes. The predictors of the decrease in serum K(+) during treatment of DH with insulin included the starting serum K(+) level, the decreases in serum values of glucose concentration and tonicity, and the increase in serum total carbon dioxide level. DH represents a risk factor for hyperkalemia. Insulin infusion is the only treatment for hyperkalemia usually required.

The Flame Photometer as Engine of Nephrology: A Biography

In the 1940s, the flame photometer made possible for the first time relatively simple and quick measurements of sodium and potassium in serum and urine. During World War II, it unexpectedly fell into the hands of John P. Peters of Yale University, who sought to understand water and electrolyte physiology and apply such knowledge to patient problems. Pupils and young associates of Peters would seed the early nephrology divisions and training programs in the United States; the flame photometer was essential to their work and that of their trainees, both Americans and international visitors. Hyponatremia and the syndrome of inappropriate antidiuretic hormone secretion became the "attribute" disorders of nephrologists. Invention of a microflame photometer fostered the revival of micropuncture and transport studies. In the 1960s, the flame photometer was linked to Leonard Skeggs' sequential automated analysis system, leading to enormous numbers of routine measurements of electrolytes. The growing number of nephrologists, then based mostly at teaching hospitals, thus found plentiful instances of sodium and potassium abnormalities to address. The autoanalyzer also catalyzed use of the anion gap, another emblem of nephrology in its early decades. Not only ideas and theories, but also the usually invisible machinery, enable the growth of a knowledge base and formation of a scientific discipline or medical specialty. Of course, the flame photometer did not itself shape the agenda of nephrology, but it allowed the most influential group of progenitors and their progeny to explore normal function and bring a strongly physiologic imperative to their daily work with patients.

Acute Electrolyte and Acid-Base Disorders in Patients With Ileostomies: A Case Series

Patients with ileostomies are well known to be susceptible to extracellular fluid volume depletion as a result of fluid and solute losses that are greater than intake. However, electrolyte and acid-base disorders accompanying these episodes of volume depletion are not well delineated. Case series. 7 patients with hospitalization because of acute acid-base disturbances at an academic medical center. In all patients, serum and urine creatinine and electrolytes were measured. In 2 patients, arterial blood pH and Pco(2) and ileal drainage electrolytes also were measured. 2 patients presented with severe metabolic alkalosis, and the remaining 5 patients had low serum total carbon dioxide values in association with hyperkalemia. All 7 had acute renal failure. Pathophysiological characteristics, diagnosis, and management of these disorders are discussed, along with considerations for long-term management of fluid and electrolyte balance. This report illustrates electrolyte and acid-base disorders encountered in patients with ileostomies from our clinical experience. We have no data about the incidence of these disorders. Patients with ileostomies can develop diverse and potentially life-threatening acute electrolyte and acid-base disorders when ileostomy drainage increases. Either metabolic acidosis or metabolic alkalosis can occur, depending on the nature and duration of the losses. These cases emphasize the need to be aware of the variety of acute electrolyte and acid-base disorders that can occur in this group of patients and to intervene rapidly when they develop.