Comparison of capillary blood ketone measurement by electrochemical method and urinary ketone in treatment of diabetic ketosis and ketoacidosis in children

Ketone production and excretion even during mild hyperglycemia and the impact of sodium-glucose co-transporter inhibition in type 1 diabetes

AIMS

We aimed to determine if ketone production and excretion are increased even at mild fasting hyperglycemia in type 1 diabetes (T1D) and if these are modified by ketoacidosis risk factors, including sodium-glucose co-transporter inhibition (SGLTi) and female sex.

METHODS

In secondary analysis of an 8-week single-arm open-label trial of empagliflozin (NCT01392560) we evaluated ketone concentrations during extended fasting and clamped euglycemia (4-6 mmol/L) and mild hyperglycemia (9-11 mmol/L) prior to and after treatment. Plasma and urine beta-hydroxybutyrate (BHB) concentrations and fractional excretion were analyzed by metabolomic analysis.

RESULTS

Forty participants (50 % female), aged 24 ± 5 years, HbA1c 8.0 ± 0.9 % (64 ± 0.08 mmol/mol) with T1D duration of 17.5 ± 7 years, were studied. Increased BHB production even during mild hyperglycemia (median urine 6.3[3.5-13.6] vs. 3.5[2.2-7.0] µmol/mmol creatinine during euglycemia, p < 0.001) was compensated by increased fractional excretion (0.9 % [0.3-1.6] vs. 0.4 % [0.2-0.9], p < 0.001). SGLTi increased production and attenuated the increased BHB fractional excretion (decreased to 0.3 % during mild hyperglycemia, p < 0.001), resulting in higher plasma concentrations (increased to 0.21 [0.05-0.40] mmol/L, p < 0.001), particularly in females (interaction p < 0.001).

CONCLUSIONS

Even mild hyperglycemia is associated with greater ketone production, compensated by urinary excretion, in T1D. However, SGLTi exaggerates production and partially reduces compensatory excretion, particularly in women.

Alterations and diagnostic performance of capillary ketonemia in pediatric acute appendicitis: a pilot study

INTRODUCTION

The diagnostic performance of capillary ketonemia (CK) has been previously evaluated in context of pediatric acute gastroenteritis. To our knowledge, there is no literature on its performance in the setting of pediatric acute appendicitis (PAA).

MATERIALS AND METHODS

In this study, 151 patients were prospectively included and divided into two groups: (1) patients with non-surgical abdominal pain in whom the diagnosis of PAA was excluded (n = 53) and (2) patients with a confirmed diagnosis of PAA (n = 98). In 80 patients (Group 1, n = 23 and group 2, n = 57) a CK was measured at the time of diagnosis. The PAA group was further classified into complicated (n = 18) and uncomplicated PAA (n = 39). Quantitative variables were compared between groups using the Mann-Whitney U test. Diagnostic performance of CK was evaluated with ROC curves.

RESULTS

CK values were 0.3 [0.1-0.9] mmol/L in group 1 and 0.7 [0.4-1.4] mmol/L in group 2 (p = 0.01). Regarding the type of PAA, CK values were 0.6 [0.4-0.9] mmol/L in uncomplicated PAA and 1.2 [0.8-1.4] mmol/L in complicated PAA (p = 0.02). The AUC for the discrimination between groups 1 and 2 was 0.68 (95% IC 0.53-0.82) (p = 0.24) and the AUC for the discrimination between uncomplicated PAA and complicated PAA was 0.69 (95% IC 0.54-0.85) (p = 0.04). The best cut-off point (group 1 vs group 2) resulted in 0.4 mmol/L, with a sensitivity of 80.7% and a specificity of 52.2%. The best cut-off point (non-complicated vs complicated PAA) resulted in 1.1 mmol/L, with a sensitivity of 61.1% and a specificity of 76.9%.

CONCLUSIONS

This study found significantly higher levels of CK in patients with PAA than in those with NSAP. Similarly, significantly higher levels were observed in patients with complicated than in those with uncomplicated PAA. Nevertheless, the diagnostic performance of CK was only moderate in the two settings analyzed. The potential usefulness of CK determination as a tool to guide the preoperative rehydration regimen of patients with PAA to prevent postoperative hyporexia and vomiting is a promising line of research and should be evaluated in future studies.

Smartphone-based mobile biosensors for the point-of-care testing of human metabolites

Rapid, accurate, portable and quantitative profiling of metabolic biomarkers is of great importance for disease diagnosis and prognosis. The recent development in the optical and electric biosensors based on the smartphone is promising for profiling of metabolites with advantages of rapid, reliability, accuracy, low-cost and multi-analytes analysis capability. In this review, we introduced the optical biosensing platforms including colorimetric, fluorescent and chemiluminescent sensing, and electrochemical biosensing platforms including wired and wireless communication. Challenges and future perspectives desired for reliable, accurate, cost-effective, and multi-functions smartphone-based biosensing systems were also discussed. We envision that such smartphone-based biosensing platforms will allow daily and comprehensive metabolites monitoring in the future, thus unlocking the potential to transform clinical diagnostics into non-clinical self-testing. We also believed that this progress report will encourage future research to develop advanced, integrated and multi-functional smartphone-based Point-of-Care testing (POCT) biosensors for the monitoring and diagnosis as well as personalized treatments of a spectrum of metabolic-disorder related diseases.

Metabolomics-driven of relationships among kidney, bone marrow and bone of rats with postmenopausal osteoporosis

As a global public health problem, postmenopausal osteoporosis (PMOP) poses a great threat to old women's health. Bone is the target organ of PMOP, and the dynamic changes of bone marrow could affect the bone status. Kidney is the main organ regulating calcium and phosphorus homeostasis. Kidney, bone marrow and bone play crucial roles in PMOP, but the relationships of the three tissues in the disease have not been completely described. Here, metabolomics was employed to investigate the disease mechanism of PMOP from the perspectives of kidney, bone marrow and bone, and the relationships among the three tissues were also discussed. Six-month-old female Sprague-Dawley (SD) rats were randomly divided into ovariectomized (OVX) group (with bilateral ovariectomy) and sham group (with sham surgery). 13 weeks after surgery, gas chromatography-mass spectrometry (GC-MS) was performed to analyze the metabolic profiling of two groups. Multivariate statistical analysis revealed that the number of differential metabolites in kidney, bone marrow and bone between the two groups were 37, 16 and 17, respectively. The common differential metabolites of the three tissues were N-methyl-L-alanine. Kidney and bone marrow had common differential metabolites, including N-methyl-L-alanine, 2-hydroxybutyric acid, (R)-3-hydroxybutyric acid (β-hydroxybutyric acid, βHBA), urea and dodecanoic acid. There were three common differential metabolites between kidney and bone, including N-methyl-L-alanine, α-tocopherol and isofucostanol. The common differential metabolite of bone marrow and bone was N-methyl-L-alanine. Some common metabolic pathways were disturbed in multiple tissues of OVX rats, such as glycine, serine and threonine metabolism, purine metabolism, tryptophan metabolism, ubiquinone and other terpenoid-quinone biosynthesis and fatty acid biosynthesis. In conclusion, our study demonstrated that profound metabolic changes have taken place in the kidney, bone marrow and bone, involving common differential metabolites and metabolic pathways. The evaluation of differential metabolites strengthened the understanding of the kidney-bone axis and the metabolic relationships among the three tissues of OVX rats.

Highly Sensitive Electrochemical Sensor for Diagnosis of Diabetic Ketoacidosis (DKA) by Measuring Ketone Bodies in Urine

In this report, we present an enzyme deposited Au electrode for an electrochemical measurement of acetylacetic acid (AcAc) in urine. The electrode has an immobilized layer of a mixture of D-β-hydroxybutyrate dehydrogenase (HBDH) and nicotinamide adenine dinucleotide (NADH) as sensing material to investigate its electroanalytical properties by means of cyclic voltammetry (CV). The modified electrodes are used for the detection of AcAc and present a linear current increase when the AcAc concentration increases. The electrode presents a limit of detection (LOD) of 6.25 mg/dL in the range of 6.25-100 mg/dL for investigation of clinical relevance. Finally, the electrode was evaluated using 20 patient samples. The measured results of urine ketone by the developed electrode were compared with the clinical results from a commercial kit, and the analysis showed good agreement. The proposed electrode was demonstrated to be a very promising platform as a miniaturized electrochemical analyzer for point-of-care monitoring of the critical biochemical parameters such as urine ketone.

Test validation, method comparison and reference range for the measurement of β-hydroxybutyrate in peripheral blood samples

Introduction

The measurement of β-hydroxybutyrate (βOHB) concentrations is a corner stone of the diagnosis of diabetic ketoacidosis and other ketonic states. The aim of this study was to perform a validation of a peripheral blood βOHB assay (Randox) on a Roche cobas c502 analyser and to establish a βOHB reference range for the validated assay.

Materials and methods

Precision, linearity and limit of detection and blank (LoD, LoB) were determined according to Clinical and Laboratory Standards Institute (CLSI) EP05-A3, EP 06-A and EP17-A2 guidelines, using commercial control material and residual patient sample pools. As method comparison, for 190 semi-quantitative measurements of urine ketones we determined the corresponding βOHB blood concentration. The reference range was based on the CLSI C28-A3 guideline, using 304 randomly selected serum samples from population based German National Cohort (GNC) study.

Results

Coefficients of variation for the validated assay ranged from 1.5% for high concentrations (3.1 mmol/L) to 6.5% for low concentrations (0.1 mmol/L). Detection capacity was LoB = 0.011 mmol/L and LoD = 0.037 mmol/L. Linearity of the assay ranged from 0.10 to 3.95 mmol/L. The agreement between the semi-quantitative urine ketone test and the βOHB blood test was moderate (Kappa = 0.66). The obtained 95% serum reference range was estimated as 0.02 to 0.28 mmol/l βOHB.

Conclusions

The Ranbut βOHB assay showed good precision and analytical performance. Our results confirm that βOHB measurement in peripheral blood is indeed a preferable alternative to the semi-quantitative measurement of urine ketones.

Smartphone-Powered Electrochemical Dongle for Point-of-Care Monitoring of Blood β-Ketone

A smartphone-powered medical dongle as a miniaturized electrochemical analyzer associated with an enzymatic β-hydroxybutyrate test strip for accurate characterization of blood ketone in peripheral whole blood at the point-of-care, which is capable of providing critical guidance for the evaluation and treatment of diabetic ketoacidosis (DK) and diabetic ketosis acid (DKA), is reported. The measured results of blood ketone by the medical dongle were compared with the clinical results from a bulky biochemical analyzer, and the analysis showed good agreement. The proposed medical smartphone-powered dongle was demonstrated to be a very promising platform as a miniaturized electrochemical analyzer for point-of-care monitoring of the critical biochemical parameters such as blood ketone and a good solution for mobile health management.

Blood Ketones: Measurement, Interpretation, Limitations, and Utility in the Management of Diabetic Ketoacidosis

Diabetic ketoacidosis (DKA) remains a common medical emergency. Over the last few years, new national guidelines have changed the focus in managing the condition from being glucose-centered to ketone-centered. With the advent of advancing technology and the increasing use of hand-held, point-of-care ketone meters, greater emphasis is placed on making treatment decisions based on these readings. Furthermore, recent warnings about euglycemic DKA occurring in people with diabetes using sodium-glucose co-transporter 2 (SGLT-2) inhibitors urge clinicians to inform their patients of this condition and possible testing options. This review describes the reasons for a change in treating DKA, and outlines the benefits and limitations of using ketone readings, in particular highlighting the difference between urine and capillary readings.

Utility of ketone measurement in the prevention, diagnosis and management of diabetic ketoacidosis

Ketone measurement is advocated for the diagnosis of diabetic ketoacidosis and assessment of its severity. Assessing the evidence base for ketone measurement in clinical practice is challenging because multiple methods are available but there is a lack of consensus about which is preferable. Evaluating the utility of ketone measurement is additionally problematic because of variability in the biochemical definition of ketoacidosis internationally and in the proposed thresholds for ketone measures. This has led to conflicting guidance from expert bodies on how ketone measurement should be used in the management of ketoacidosis. The development of point-of-care devices that can reliably measure the capillary blood ketone β-hydroxybutyrate (BOHB) has widened the spectrum of applications of ketone measurement, but whether the evidence base supporting these applications is robust enough to warrant their incorporation into routine clinical practice remains unclear. The imprecision of capillary blood ketone measures at higher values, the lack of availability of routine laboratory-based assays for BOHB and the continued cost-effectiveness of urine ketone assessment prompt further discussion on the role of capillary blood ketone assessment in ketoacidosis. In the present article, we review the various existing methods of ketone measurement, the precision of capillary blood ketone as compared with other measures, its diagnostic accuracy in predicting ketoacidosis and other clinical applications including prevention, assessment of severity and resolution of ketoacidosis.

Accuracy of capillary blood 3-β-hydroxybutyrate determination for the detection and treatment of canine diabetic ketoacidosis

In human medicine, diagnosis of diabetic ketoacidosis (DKA) is usually based on measurement of capillary 3-β-hydroxybutyrate (3-HB) with a hand held ketone sensor. This study was conducted to determine if measurement of capillary 3-HB could be useful for the diagnosis and monitoring of canine DKA. Fifteen dogs with diabetic ketosis and 10 with DKA were evaluated. Paired measurements of 3-HB of capillary and venous blood samples were analysed by the electrochemical sensor and reference method. Use of capillary 3-HB measurement during DKA management was then evaluated through simultaneous measurements of capillary 3-HB, urinary AcAc and venous blood gas analysis. Good agreement between capillary and venous 3-HB measurement was detected by the electrochemical sensor and reference method. Monitoring treatment of DKA revealed a significant correlation between capillary 3-HB and acidosis markers, while no significant correlation was observed between AcAc and acidosis markers. A cut-off value of capillary blood 3-HB >3.8 mmol/L for diagnosis of DKA resulted in 70% and 92% sensitivity and specificity. The electrochemical sensor accurately measures 3-HB concentration in both capillary and venous blood samples, is accurate in diagnosing canine DKA, and appears to reflect the patient's metabolic status during DKA treatment.

Blood β-hydroxybutyrate vs. urine acetoacetate testing for the prevention and management of ketoacidosis in Type 1 diabetes: a systematic review

AIM

Diabetic ketoacidosis is a life-threatening complication of Type 1 diabetes. Blood β-hydroxybutyrate testing is now widely available as an alternative to urine acetoacetate testing for detecting ketosis. The aim of this study was to review the effectiveness of capillary or serum β-hydroxybutyrate compared with urine acetoacetate testing in prevention and management of diabetic ketoacidosis.

METHODS

MEDLINE, EMBASE, EBM Reviews, The Cochrane Library and CINAHL (until April 2012, no language restrictions, studies in humans) were searched for experimental and observational studies comparing the effectiveness of blood β-hydroxybutyrate and urine acetoacetate testing. Outcomes examined were prevention of diabetic ketoacidosis, time to recovery from diabetic ketoacidosis, healthcare costs and patient or caregiver satisfaction. Additional sources included reference lists, conference proceedings and contact with experts in the field.

RESULTS

Four studies (two randomized controlled trials and two cohort studies) met eligibility criteria, including 299 participants across 11 centres. Risk of bias was low to moderate. Blood ketone testing compared with urine testing was associated with reduced frequency of hospitalization (one study), reduced time to recovery from diabetic ketoacidosis (three studies), cost benefits (one study) and greater satisfaction (one study, intervention group only). No study assessed prevention of diabetic ketoacidosis. Meta-analysis could not be performed because of heterogeneity in study design and published data.

CONCLUSIONS

There is evidence suggesting that blood β-hydroxybutyrate testing is more effective than urine acetoacetate testing in reducing emergency department assessment, hospitalization and time to recovery from diabetic ketoacidosis, as well as potentially lowering healthcare expenditure. Further research in both young people and adults is needed.

The role of point-of-care β-hydroxybutyrate testing in the diagnosis of diabetic ketoacidosis: a review

The number of patients with diabetes and diabetes-related complications is increasing. Rapid and accurate diagnosis is key to efficiently providing the appropriate level of care for patients with diabetes. When faced with a hyperglycemic patient (ie, blood glucose level > 250 mg/dL), the prevailing attitude among health care providers is to "think worst first," and common clinical practice is to perform an evaluation for diabetic ketoacidosis (DKA). Traditionally, diagnosing DKA in accordance with the American Diabetes Association guidelines requires performing ≥ 2 (possibly 3) tests to obtain measurements for blood glucose, serum bicarbonate, serum pH, and serum anion gap levels, as well as measurements of either urine or serum ketone bodies. Recently, commercial point-of-care β-hydroxybutyrate measurement devices have become readily accessible and less expensive. These devices offer the potential to simplify clinicians' diagnostic approach to hyperglycemic patients. In this evidence-based literature review, we describe the use of point-of-care β-hydroxybutyrate testing for diagnosing DKA, and discuss its limitations in determining DKA severity.

Point-of-care beta-hydroxybutyrate testing for assessing diabetic ketoacidosis severity prior to treatment in the emergency department

We prospectively evaluated the correlation between point-of-care β-OHB values and DKA severity at time of initial diagnosis in 54 patients. The correlation coefficients between β-OHB and pH, bicarbonate and anion gap were 0.33, 0.25 and 0.16, respectively. We conclude that point-of-care β-OHB absolute values cannot reliably assess DKA severity.

Effects of a ketogenic diet on the quality of life in 16 patients with advanced cancer: A pilot trial

BACKGROUND

Tumor patients exhibit an increased peripheral demand of fatty acids and protein. Contrarily, tumors utilize glucose as their main source of energy supply. Thus, a diet supplying the cancer patient with sufficient fat and protein for his demands while restricting the carbohydrates (CHO) tumors thrive on, could be a helpful strategy in improving the patients' situation. A ketogenic diet (KD) fulfills these requirements. Therefore, we performed a pilot study to investigate the feasibility of a KD and its influence on the quality of life of patients with advanced metastatic tumors.

METHODS

Sixteen patients with advanced metastatic tumors and no conventional therapeutic options participated in the study. The patients were instructed to follow a KD (less than 70 g CHO per day) with normal groceries and were provided with a supply of food additives to mix a protein/fat shake to simplify the 3-month intervention period. Quality of life [assessed by EORTC QLQ-C30 (version 2)], serum and general health parameters were determined at baseline, after every two weeks of follow-up, or after drop out. The effect of dietary change on metabolism was monitored daily by measuring urinary ketone bodies.

RESULTS

One patient did not tolerate the diet and dropped out within 3 days. Among those who tolerated the diet, two patients died early, one stopped after 2 weeks due to personal reasons, one felt unable to stick to the diet after 4 weeks, one stopped after 6 and two stopped after 7 and 8 weeks due to progress of the disease, one had to discontinue after 6 weeks to resume chemotherapy and five completed the 3 month intervention period. These five and the one who resumed chemotherapy after 6 weeks report an improved emotional functioning and less insomnia, while several other parameters of quality of life remained stable or worsened, reflecting their very advanced disease. Except for temporary constipation and fatigue, we found no severe adverse side effects, especially no changes in cholesterol or blood lipids.

CONCLUSIONS

These pilot data suggest that a KD is suitable for even advanced cancer patients. It has no severe side effects and might improve aspects of quality of life and blood parameters in some patients with advanced metastatic tumors.

Eating disorders and diabetic ketoacidosis in a pregnant woman with type 1 diabetes: a case report

OBJECTIVE

To describe a case of diabetic ketoacidosis (DKA) in a pregnant woman with type 1 diabetes (T1DM) and disordered eating behaviour treated with a continuous subcutaneous insulin infusion, and to discuss some aspects of the monitoring and management of DKA in pregnancy and whether a pump is the safest therapeutic choice in the presence of some eating disorders.

CASE REPORT

This 26-year-old Caucasian woman affected by T1DM was hospitalised during the last weeks of her fourth pregnancy because of DKA due to disordered eating. She was treated with a fluid infusion, intravenous insulin, and her electrolyte imbalance was carefully corrected. An elective cesarean section was performed after the correction of DKA in the 34th week (+6 days) of gestation.

CONCLUSIONS

We suggest that pregnancy in T1DM women with eating disorders may not be rare. The prevention, early recognition and aggressive management of DKA can minimise the possible complications, and is mandatory for the safety of the fetus and mother.

Metabolic management of brain cancer

Malignant brain tumors are a significant health problem in children and adults. Conventional therapeutic approaches have been largely unsuccessful in providing long-term management. As primarily a metabolic disease, malignant brain cancer can be managed through changes in metabolic environment. In contrast to normal neurons and glia, which readily transition to ketone bodies (β-hydroxybutyrate) for energy under reduced glucose, malignant brain tumors are strongly dependent on glycolysis for energy. The transition from glucose to ketone bodies as a major energy source is an evolutionary conserved adaptation to food deprivation that permits the survival of normal cells during extreme shifts in nutritional environment. Only those cells with a flexible genome and normal mitochondria can effectively transition from one energy state to another. Mutations restrict genomic and metabolic flexibility thus making tumor cells more vulnerable to energy stress than normal cells. We propose an alternative approach to brain cancer management that exploits the metabolic flexibility of normal cells at the expense of the genetically defective and metabolically challenged tumor cells. This approach to brain cancer management is supported from recent studies in mice and humans treated with calorie restriction and the ketogenic diet. Issues of implementation and use protocols are presented for the metabolic management of brain cancer.

The performance of a glucose-ketone meter in the diagnosis of diabetic ketoacidosis in patients with type 2 diabetes in the emergency room

BACKGROUND

Diabetic ketoacidosis (DKA) is a serious metabolic complication. One of its precipitating causes is insulin omission. DKA requires early diagnosis and strict glucose control, which increases the use of glucose meters in the Emergency Room (ER). We aimed to determine the performance of a glucose-ketone meter in the diagnosis of DKA.

METHODS

From 450 type 2 diabetes mellitus insulin-treated patients attending the ER with a capillary glucose level >13.9 mmol/L, 50 patients (26 men and 24 women, mean age 60.2 +/- 8.2 years) had DKA. Capillary glucose and beta-hydroxybutyrate (beta-OHB) were measured with the Precision-Xtra device (Abbott Laboratories, Abingdon, UK). Serum glucose and biochemical parameters were measured on an automatic analyzer; serum beta-OHB was determined using an enzymatic end-point spectrophotometric method. Urine ketones were determined using a semiquantitative assay (Ketodiastix, Bayer Diagnostics, Stoke Poges, Slough, UK).

RESULTS

Serum and capillary beta-OHB values were highly correlated (r = 0.99, P < 0.001), and the mean difference between them was 0.49 mmol/L (95% confidence interval [CI], 0.35-0.95 mmol/L; P = 0.81). Similarly, serum and capillary glucose values were significantly correlated (r = 0.86, P < 0.001), and the mean difference between them was 0.43 mmol/L (95% CI, 0.82-0.93 mmol/L; P = 0.71). Patients with DKA were inadequately treated with insulin and missed clinic appointments: 80% of patients with DKA compared to 20% of patients without DKA. In all cases, DKA was attributed to insulin omission. Capillary ketonemia (beta-OHB >3.0 mmol/L) had the highest performance (sensitivity 99.87%, specificity 92.89%, positive predictive value 92.89%) for the diagnosis of DKA compared with serum ketonemia (sensitivity 90.45%, specificity 88.65%, positive predictive value 87.76%) or ketonuria (sensitivity 89.89%, specificity 52.73%, positive predictive value 41.87%).

CONCLUSIONS

Implementation of measures such as home glucose and ketone monitoring can possibly decrease the number of hospital admissions due to DKA.

Metabolic management of glioblastoma multiforme using standard therapy together with a restricted ketogenic diet: Case Report

Background

Management of glioblastoma multiforme (GBM) has been difficult using standard therapy (radiation with temozolomide chemotherapy). The ketogenic diet is used commonly to treat refractory epilepsy in children and, when administered in restricted amounts, can also target energy metabolism in brain tumors. We report the case of a 65-year-old woman who presented with progressive memory loss, chronic headaches, nausea, and a right hemisphere multi-centric tumor seen with magnetic resonance imaging (MRI). Following incomplete surgical resection, the patient was diagnosed with glioblastoma multiforme expressing hypermethylation of the MGMT gene promoter.

Methods

Prior to initiation of the standard therapy, the patient conducted water-only therapeutic fasting and a restricted 4:1 (fat: carbohydrate + protein) ketogenic diet that delivered about 600 kcal/day. The patient also received the restricted ketogenic diet concomitantly during the standard treatment period. The diet was supplemented with vitamins and minerals. Steroid medication (dexamethasone) was removed during the course of the treatment. The patient was followed using MRI and positron emission tomography with fluoro-deoxy-glucose (FDG-PET).

Results

After two months treatment, the patient's body weight was reduced by about 20% and no discernable brain tumor tissue was detected using either FDG-PET or MRI imaging. Biomarker changes showed reduced levels of blood glucose and elevated levels of urinary ketones. MRI evidence of tumor recurrence was found 10 weeks after suspension of strict diet therapy.

Conclusion

This is the first report of confirmed GBM treated with standard therapy together with a restricted ketogenic diet. As rapid regression of GBM is rare in older patients following incomplete surgical resection and standard therapy alone, the response observed in this case could result in part from the action of the calorie restricted ketogenic diet. Further studies are needed to evaluate the efficacy of restricted ketogenic diets, administered alone or together with standard treatment, as a therapy for GBM and possibly other malignant brain tumors.

An assessment of the population variance of the strong ion gap using Monte Carlo simulation

The strong ion gap is a derived parameter used to quantify clinically significant but unmeasured charged species in human plasma. In the general population the strong ion gap has a mean value of approximately 0.0 mEq/l, but at present no reference range exists. This severely limits its clinical application. In order to establish a reference range, a 95% confidence interval around the population mean must be calculated. As each of the variables that make up the strong ion gap have their own unique and different means and standard deviations, simple methods of pooled variance can not be used to calculate this interval. In place of a direct solution, Monte Carlo methodology was employed using known reference standard deviations to construct a large sample of a simulated population. In addition, the partial correlation between the plasma concentrations of sodium and chloride was included in the calculations. Sample sets of 20,000 were simulated, each giving a normally distributed strong ion gap. A 95% confidence interval of 3.9+/-6.4 mEq/l was derived. Depending on the degree of strong ion correlation, minima and maxima for this reference range were calculated as 3.9+/-5.1 mEq/l and 3.9+/-7.6 mEq/l respectively. Reasons for the positive bias in the mean strong ion gap result are examined briefly.