Elevated plasma beta-hydroxybutyrate concentrations without ketonuria in healthy insulin-dependent diabetic patients

Continuous Ketone Monitoring Consensus Report 2021

This article is the work product of the Continuous Ketone Monitoring Consensus Panel, which was organized by Diabetes Technology Society and met virtually on April 20, 2021. The panel consisted of 20 US-based experts in the use of diabetes technology, representing adult endocrinology, pediatric endocrinology, advanced practice nursing, diabetes care and education, clinical chemistry, and bioengineering. The panelists were from universities, hospitals, freestanding research institutes, government, and private practice. Panelists reviewed the medical literature pertaining to ten topics: (1) physiology of ketone production, (2) measurement of ketones, (3) performance of the first continuous ketone monitor (CKM) reported to be used in human trials, (4) demographics and epidemiology of diabetic ketoacidosis (DKA), (5) atypical hyperketonemia, (6) prevention of DKA, (7) non-DKA states of fasting ketonemia and ketonuria, (8) potential integration of CKMs with pumps and automated insulin delivery systems to prevent DKA, (9) clinical trials of CKMs, and (10) the future of CKMs. The panelists summarized the medical literature for each of the ten topics in this report. They also developed 30 conclusions (amounting to three conclusions for each topic) about CKMs and voted unanimously to adopt the 30 conclusions. This report is intended to support the development of safe and effective continuous ketone monitoring and to apply this technology in ways that will benefit people with diabetes.

Improved cerebral energetics and ketone body metabolism in db/db mice

It is becoming evident that type 2 diabetes mellitus is affecting brain energy metabolism. The importance of alternative substrates for the brain in type 2 diabetes mellitus is poorly understood. The aim of this study was to investigate whether ketone bodies are relevant candidates to compensate for cerebral glucose hypometabolism and unravel the functionality of cerebral mitochondria in type 2 diabetes mellitus. Acutely isolated cerebral cortical and hippocampal slices of db/db mice were incubated in media containing [U-¹³C]glucose, [1,2-¹³C]acetate or [U-¹³C]β-hydroxybutyrate and tissue extracts were analysed by mass spectrometry. Oxygen consumption and ATP synthesis of brain mitochondria of db/db mice were assessed by Seahorse XFe96 and luciferin-luciferase assay, respectively. Glucose hypometabolism was observed for both cerebral cortical and hippocampal slices of db/db mice. Significant increased metabolism of [1,2-¹³C]acetate and [U-¹³C]β-hydroxybutyrate was observed for hippocampal slices of db/db mice. Furthermore, brain mitochondria of db/db mice exhibited elevated oxygen consumption and ATP synthesis rate. This study provides evidence of several changes in brain energy metabolism in type 2 diabetes mellitus. The increased hippocampal ketone body utilization and improved mitochondrial function in db/db mice, may act as adaptive mechanisms in order to maintain cerebral energetics during hampered glucose metabolism.

Prevalence of ketosis, ketonuria, and ketoacidosis during liberal glycemic control in critically ill patients with diabetes: an observational study

Background

It is uncertain whether liberal glucose control in critically ill diabetic patients leads to increased ketone production and ketoacidosis. Therefore, we aimed to assess the prevalence of ketosis, ketonuria and ketoacidosis in critically ill diabetic patients treated in accordance with a liberal glycemic control protocol.

Methods

We performed a prospective observational cohort study of 60 critically ill diabetic patients with blood and/or urine ketone bodies tested in ICU. All patients were treated according to a liberal glucose protocol targeting a blood glucose level (BGL) between 10 and 14 mmol/l in a single tertiary intensive care unit in Australia. We measured quantitative bedside blood 3-beta-hydroxybutyrate (β-OHB) and semi-quantitative urine ketones on ICU admission and daily during ICU stay, for a maximum of 10 consecutive days.

Results

Median blood β-OHB level on admission was 0.3 (0.1, 0.8) mmol/l. Ketoacidosis was rare (3 %), but some level of ketosis (β-OHB ≥0.6 mmol/l) was found in 38 patients (63 %) early during their ICU stay. However, there was no significant difference in prevalence or severity of ketonemia and ketonuria among patients with BGL above (permissive hyperglycemia) or below 10 mmol/l. On multivariable linear regression analysis there was no association between blood ketone levels and BGL, HbA1c, lactate levels, hematocrit, catecholamine infusion or APACHE III score. In contrast, blood ketone levels tended to be higher after cardiopulmonary bypass surgery (P = 0.06).

Conclusions

Liberal glycemic control in critically ill diabetic patients does not appear to be associated with a high prevalence of ketoacidosis or ketonemia. Moreover, ketosis is typically present on admission and resolves rapidly. Finally, cardiopulmonary bypass surgery may be an important trigger of ketone body production.

Trial registration

Australian New Zealand Clinical Trials Registry (ACTRN12615000216516; trial registration date 5 March 2015).

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1462-7) contains supplementary material, which is available to authorized users.

An enzymatic method to determine γ-hydroxybutyric acid in serum and urine

BACKGROUND

Gamma-hydroxybutyric acid (GHB) has become one of the most dangerous illicit drugs of abuse today. It is used as a recreational and date rape drug because of its depressant effect on the central nervous system, which may cause euphoria, amnesia, respiratory arrest, and coma. There is an urgent need for a simple, easy-to-use assay for GHB determination in urine and blood. In this article, a rapid enzymatic assay adapted to clinical chemistry analyzers for the detection of GHB is presented.

METHODS

The described GHB enzymatic assay is based on a recombinant GHB dehydrogenase. The full validation of the assay was performed on a Konelab 30 analyzer (Thermo Fisher Scientific).

RESULTS

The analytical sensitivity was <1.5 mg/L, whereas the functional sensitivity was 4.5 mg/L in serum and 2.8 mg/L in urine. The total imprecision coefficient of variation (CV) was <9.8% in serum and <7.9% in urine. The within-run imprecision showed a CV of <3.8% in serum and <4.6% in urine. The assay was linear within the range 5-250 mg/L. Mean recoveries were 109% in serum and 105% in urine. No cross-reactivity was observed for tested GHB analogues and precursors. Comparison of GHB-positive samples showed an excellent correlation with ion chromatography, gas chromatography-mass spectrometry, and liquid chromatography associated to tandem mass spectrometry. Except for ethanol, no substantial interference from serum constituents and some drugs was observed.

CONCLUSIONS

This automated GHB assay is fully quantitative and allows the accurate measurement of GHB in serum and urine. It can be used as a rapid screening assay for the determination of GHB in intoxicated or overdosed patients.

Efficacy of plasma beta-hydroxybutyrate concentration as a marker for diabetes mellitus in acutely sick cats

Urine ketone measurement is routinely performed in cats with diabetes mellitus to identify impending or established ketoacidosis. Studies using the urinary ketone dipstick test have shown that ketonuria is common in cats with newly diagnosed untreated diabetes mellitus. This test has a low sensitivity as it quantifies the less abundant ketone acetoacetate. The objective of the present study was to determine if ketonaemia is an inherent biochemical finding in untreated feline diabetes mellitus by measuring plasma ss-hydroxybutyrate (ss-OHB) in acutely sick cats. In 122 sick cats (37 diabetic and 85 non-diabetic cats) plasma ss-OHB, glucose, fructosamine, total protein and thyroxine were measured as part of the routine work up. Diabetic cats had significantly elevated ss-OHB values and ss-OHB measurement was a sensitive and specific test to identify diabetes mellitus. The area under the receiver operating characteristic (ROC) curve was 0.93. The cut off value with the highest positive likelihood ratio was 0.58 mmol/l. These results suggest that determination of plasma ss-OHB concentration is a useful method to distinguish between diabetic and non-diabetic sick cats.

Evaluation of a portable meter to measure ketonemia and comparison with ketonuria for the diagnosis of canine diabetic ketoacidosis

BACKGROUND

The diagnosis of canine diabetic ketoacidosis (DKA) usually is based on measurement of urinary acetoacetate (ketonuria). In humans, this test is less sensitive and specific than blood 3-beta-hydroxybutyrate (ketonemia) evaluation.

HYPOTHESIS

Ketonemia measurement using a portable meter is more accurate than ketonuria determination with a dipstick to diagnose canine DKA.

ANIMALS

Seventy-two client-owned diabetic dogs with ketonemia, ketonuria, or both.

METHODS

Prospective observational study. Based on blood bicarbonate concentration and anion gap, dogs were divided into 2 groups: patients with DKA (n= 25); patients with diabetic ketosis (n= 47). Sensitivity, specificity, and positive and negative likelihood ratio (LR) at different cut-off points were determined for both ketonemia and ketonuria. Receiver operating characteristic (ROC) analysis was used to assess the accuracy of each diagnostic test to diagnose DKA.

RESULTS

With regard to ketonemia, cut-off values of 2.3 and 4.3 mmol/L revealed 100% sensitivity and 100% specificity, respectively, whereas cut-off values of 2.8 and 3.5 mmol/L showed a -LR of 0.05 and a + LR of 13.16, respectively. With regard to ketonuria, a cut-off value of 1+ revealed 92% sensitivity, 40% specificity, and -LR of 0.20, whereas a cut-off value of 3+ revealed 44% sensitivity, 94% specificity, and +LR of 6.89. The areas under the ROC curves for the ketonemia and ketonuria tests were significantly different (0.97 and 0.81, respectively, P= .003).

CONCLUSIONS AND CLINICAL IMPORTANCE

Measurement of ketonemia is accurate and more effective than measurement of ketonuria to diagnose canine DKA.

Ketone measurements using dipstick methodology in cats with diabetes mellitus

OBJECTIVES

To compare the results of urine and plasma ketone dip test in a group of diabetic cats with possible ketosis or ketoacidosis, using laboratory plasma beta-hydroxybutyrate measurements as the gold standard.

METHODS

According to clinical examinations, plasma beta-hydroxybutyrate measurements and venous blood gas analysis, 54 cats with diabetes mellitus were classified as non-ketotic (n=3), ketotic (n=40) or ketoacidotic (n=11). Plasma and urine acetoacetate concentrations were determined using urine reagent strips.

RESULTS

Although there was a significant positive correlation between blood and urine ketone measurements (r=0.695, P<0.001), the results differed significantly (Z=-3.494, P<0.001). Using the differential positive rates, the best cut-off value to detect cats with ketoacidosis was 1.5 mmol/l for urine and 4 mmol/l for plasma. The sensitivity/specificity was 82/95 per cent for urine and 100/88 per cent for plasma, respectively.

CLINICAL SIGNIFICANCE

The urine and plasma ketone dip tests have a different diagnostic accuracy, and results have to be interpreted differently. Because of its high sensitivity, the plasma ketone dip test performs better than the urine ketone dip test to identify cats with impending or established ketoacidosis.

Bedside detection of urine beta-hydroxybutyrate in diagnosing metabolic acidosis

OBJECTIVES

While critically important, the rapid identification of the etiology of metabolic acidosis (MA) may be labor-intensive and time-consuming. Alcoholic, starvation, and severe diabetic ketoacidosis (AKA, SKA, and DKA, respectively) may produce beta-hydroxybutyrate (BOHB) in marked excess of acetone (ACET) and acetoacetate (AcAc). Unfortunately, current urine dipstick technology poorly detects ACET and cannot measure BOHB. The inability to detect BOHB might delay therapy for ketoacidoses or provoke unnecessary evaluation or empiric treatment of other causes of MA, such as toxic alcohol poisoning. The authors tested the previous assertion that commonly available hydrogen peroxide (H(2)O(2)) would improve BOHB detection. The effectiveness of alkalinization and use of a silver nitrate (AgNO(3)) catalyst was also assessed.

METHODS

Control and urine test specimens containing from 0.5 to 800 mmol/L ACET, AcAc, and BOHB were prepared. Urine specimens were oxidized with H(2)O(2) (3%) 1:9 (H(2)O(2):urine), alkalinized with potassium hydroxide (KOH; 10%), exposed to AgNO(3) sticks, or altered with a combination of these methods in a random fashion. Three emergency physicians (EPs) blinded to the preparation technique evaluated urine dipsticks (Multistix, Bayer Corp.) placed in the specimens for "ketones."

RESULTS

Multistix detected AcAc appropriately; ACET was detected only at high concentrations of >or=600 mmol/L. Multistix failed to measure BOHB at all concentrations tested. H(2)O(2) improved urinary BOHB detection, although not to clinically relevant levels (40 mmol/L). Alkalinization and AgNO(3) sticks did not improve BOHB detection beyond this threshold.

CONCLUSIONS

Addition of H(2)O(2) (3%), alkalinization, or AgNO(3) sticks did not improve clinically meaningful urine BOHB detection. Clinicians should use direct methods to detect BOHB when suspected.

Correlation between urine ketones (acetoacetate) and capillary blood ketones (3-beta-hydroxybutyrate) in hyperglycaemic patients

AIMS

To facilitate the transition from urine ketones (acetoacetate) to capillary blood ketones (3-beta-hydroxybutyrate), we studied the correlation between these two tests.

METHODS

Retrospective study of all patients with blood glucose greater than or equal to 2.5 g/l on arrival in the Emergency Department. We studied the correlation between urine ketones (Clinitek 50, Bayer) and capillary blood ketones (Optium, Abbott). We then compared the relative risks (RR) of ketoacidosis and hospitalization associated with each of these tests.

RESULTS

In 33 months, 529 adult patients with both urine and blood testing for ketones were enrolled (ketoacidosis 8%, admission rate 49%). Urine ketones scored as +, ++ and +++ corresponded to median capillary blood ketone levels of 0.5 mmol/l (IQR: 0.1-0.9), 0.7 mmol/l (IQR: 0.2-1.8) and 3 mmol/l (IQR: 1.4-5.2), respectively. RRs of ketoacidosis or hospitalization associated with blood ketones greater than or equal to 3 mmol/l were higher than those associated with +++ urine ketones: 74 (95% confidence interval [CI]: 48-88) and 2.9 (95% CI: 2.5-3) versus 31 (95% CI: 18-45) and 2 (95% CI: 1.7-2.1), respectively.

CONCLUSIONS

In hyperglycaemic patients in the Emergency Department, a good correlation was observed between urine ketones and capillary blood ketones for low values, but a poor correlation was observed for high values. Either test can therefore be used to exclude ketosis, but the capillary blood ketones test is more accurate to confirm ketoacidosis.

Diabetic ketoacidosis: risk factors and management strategies

Diabetic ketoacidosis (DKA) is the most common hyperglycemic emergency in patients with diabetes mellitus. DKA most often occurs in patients with type 1 diabetes, but patients with type 2 diabetes are susceptible to DKA under stressful conditions, such as trauma, surgery, or infections. DKA is reported to be responsible for more than 100 000 hospital admissions per year in the US, and accounts for 4-9% of all hospital discharge summaries among patients with diabetes. Treatment of patients with DKA uses significant healthcare resources and accounts for 1 out of every 4 healthcare dollars spent on direct medical care for adult patients with type 1 diabetes in the US. Recent studies using standardized written guidelines for therapy have demonstrated a mortality rate of less than 5%, with higher mortality rates observed in elderly patients and those with concomitant life-threatening illnesses. Worldwide, infection is the most common precipitating cause for DKA, occurring in 30-50% of cases. Urinary tract infection and pneumonia account for the majority of infections. Other precipitating causes are intercurrent illnesses (i.e., surgery, trauma, myocardial ischemia, pancreatitis), psychological stress, and non-compliance with insulin therapy. The triad of uncontrolled hyperglycemia, metabolic acidosis and increased total body ketone concentration characterizes DKA. These metabolic derangements result from the combination of absolute or relative insulin deficiency and increased levels of counter-regulatory hormones (glucagon, catecholamines, cortisol, and growth hormone). Successful treatment of DKA requires frequent monitoring of patients, correction of hypovolemia and hyperglycemia, replacement of electrolyte losses, and careful search for the precipitating cause. Since the majority of DKA cases occur in patients with a known history of diabetes, this acute metabolic complication should be largely preventable through early detection, and by the education of patients, healthcare professionals, and the general public. The frequency of hospitalizations for DKA has been reduced following diabetes education programs, improved follow-up care, and access to medical advice. Novel approaches to patient education incorporating a variety of healthcare beliefs and socioeconomic issues are critical to an effective prevention program.

Urinary endogenous concentrations of GHB and its isomers in healthy humans and diabetics

Urinary endogenous concentrations of gamma-hydroxybutyric acid (GHB), alpha-hydroxybutyric acid (AHB) and beta-hydroxybutyric acid (BHB) have been investigated for both healthy humans and diabetics by using a newly optimized GC-MS procedure. The endogenous concentrations in healthy volunteers' urine ranged 0.16-2.14 microg/ml for GHB, 0.10-2.68 microg/ml for AHB and 8.51-34.7 microg/ml for BHB. In diabetics, the concentrations ranged 0.17-3.03 microg/ml for GHB, 0.14-124 microg/ml for AHB and 4.94-4520 microg/ml for BHB. Although notably elevated BHB and AHB concentrations were observed for severely uncontrolled diabetics, their GHB concentrations ranged within or near the range seen in healthy humans. The results of this study confirm the previously suggested 10 microg/ml cutoff concentration of urinary GHB to distinguish exogenous GHB, even for uncontrolled diabetic patients suffering severe ketoacidosis.

Urinary acetoacetate or capillary ??-hydroxybutyrate for the diagnosis of ketoacidosis in the Emergency Department setting

OBJECTIVES

We compared the semiquantitative measurement of acetoacetate using urinary dipsticks with the bedside quantitative fingerprick measurement of the principal ketone bodies 3-beta-hydroxybutyrate, for the diagnosis of ketoacidosis.

METHODS

This is a one year retrospective study of patients who presented with hyperglycemia levels of 250 mg/l or greater in the Emergency Department setting. We compared the sensitivity, specificity, and predictive value of ketonuria and ketonemia for the diagnosis of ketoacidosis (urine or blood ketone bodies, blood bicarbonates <20 mmol/l, anion gap >16 meq/l) in a sample of patients for whom the levels of ketone bodies in the blood and urine as well as serum electrolytes were available.

RESULTS

We studied 355 hyperglycemic patients. The median time between arrival and dipstick testing was 21 min, and was greater than 2 h in more than 10% of cases. Comparison between ketonuria and ketonemia was performed in 173 patients (6% with diabetic ketoacidosis). Ketonuria equal to or less than one cross or a 3-beta-hydroxybutyrate value lower than 3 mmol/l enabled ketoacidosis to be excluded (negative predictive value 100%). At two-cross cutoff points for ketonuria and at the 3 mmol/l cutoff point for ketonemia, the two tests had the same sensitivity (100%), but the specificity of 3-beta-hydroxybutyrate (94%) was significantly higher (P<0.0001) than that of ketonuria (77%). The best positive predictive value for ketonemia was obtained at the 5 mmol/l cutoff point (100%) and for ketonuria at the three-cross cutoff point (26%). At the three-cross cutoff point for ketonuria and at the 5 mmol/l cutoff point for ketonemia, the two tests had the same negative likelihood ratio (0.1), but the positive likelihood ratio of 3-beta-hydroxybutyrate (infinite) was higher than that of ketonuria.

CONCLUSION

The measurement of 3-beta-hydroxybutyrate in capillary blood is faster and more effective than the use of dipsticks in the urine to detect ketoacidosis in the Emergency Department setting.

Change in glycemic control predicts change in weight in adolescent boys with type 1 diabetes

OBJECTIVE

To characterize the intraindividual relationships between changes in weight, glycosylated hemoglobin (HbA1c) levels, and reported total daily insulin dose between clinic visits in adolescent boys with type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

Intraindividual changes in HbA1c, anthropometric data, and reported total daily insulin dose between consecutive visits for 94 adolescent boys with T1D were analyzed.

RESULTS

Average quarterly weight gain was 2.8 kg during periods of improving, 1.5 kg during periods of minimal change, and 0.8 kg during periods of worsening glycemic control (improving vs. minimal change p < 0.001; minimal change vs. worsening p = 0.11; improving vs. worsening p < 0.001). Analyzing the quarterly weight velocity according to change in reported total daily dose of insulin, we found significantly greater weight gain during intervals when the family reported a decreasing insulin dose compared to intervals when the family reported no change in insulin dose (p = 0.003). Conversely, weight change during periods of reported increasing insulin dose was similar to that when the family reported that the boy's insulin dose did not change.

CONCLUSIONS

Quarterly weight velocity was correlated with degree of change in glycemic control between visits in adolescent boys with T1D. When weight loss or inadequate weight gain and worsening glycemic control occur, the possibility of insulin omission must be explored. Reviewing the adolescent's growth data and then the division of responsibilities for diabetes management within the family, clinicians must reconcile discrepancies between weight velocity and a reportedly adequate dose of insulin.

When should determination of ketonemia be recommended?

Diabetic ketoacidosis is a serious complication of type diabetes. beta-Hydroxybutyrate (beta-OHB) accounts for about 75% of ketones, and blood concentration can be determined with a sensor. The aim of this study was to investigate the frequency and degree of ketonemia in daily life of children with diabetes and to make a base for recommendations for determination of ketonemia in clinical practice. During 3 months 45 patients with type 1 diabetes since 1-10 years old (mean 4.4 +/- 3.3 years old) at the pediatric clinic in Linköping, Sweden, performed 24-h profiles (eight determinations) in 2 weeks with blood glucose and beta-OHB. The children performed 11,189 blood glucose and 7,057 beta-OHB measurements. Only 0.3% (n = 21) of beta-OHB measurements were > or = 1.0 mmol/L. An beta-OHB concentration > 0.2 mmol/L was more common in the morning than during the rest of the day (p < 0.001). Young children (4-7 years old) had values > or = 0.2 mmol/L more often than adolescents (p < 0.001). Blood glucose values > 15 mmol/L were more often accompanied by beta-OHB > 0.2 mmol/L (p < 0.001). High beta-OHB concentrations are rare in diabetic children with reasonably good metabolic control. Already a value > 0.4 mmol/L seems abnormal, and we recommend that patients retest glucose and ketones with beta-OHB > 0.4 mmol/L. Furthermore, we recommend that diabetic children and adolescents measure beta-OHB when symptoms like nausea or vomiting occur to differentiate ketoacidosis from gastroenteritis, and during infections, during periods with high blood glucose (> 15 mmol/L), and if they notice ketonuria. Monitoring beta-OHB should be routine for patients on pump therapy.

Unrecognized persistence of beta-hydroxybutyrate in diabetic ketoacidosis

We quantitated serial serum beta-hydroxybutyrate (beta-OHB) levels using the Ketosite method in 9 children with IDDM who were treated for diabetic ketoacidosis (DKA) and compared them to urinary ketone measurements by dipstick. Persistent elevations of serum beta-OHB were seen in six patients when the urine became clear of ketones; five of these patients had a recurrence of ketonuria. We conclude that many patients recovering from ketoacidosis have continuing elevations of beta-OHB after the urine is free of ketones and this unrecognized abnormality is the likely cause of recurrence of the ketonuria. We recommend that fluid therapy be continued beyond clearance of ketonuria and suggest using the Ketosite method to document restoration of normal serum beta-OHB levels in patients recovering from DKA.

Sick-day management in type 1 diabetes

Illness and stress are common occurrences. For the person with type 1 diabetes, these events can be triggers for counterregulation and [table: see text] subsequent metabolic deterioration if there is no attention to diabetes management tasks. Sick-day management requires increased monitoring of blood glucose and assessment for ketosis. Although urine testing for ketones has been the standard approach to sick-day management, new technology for self-monitoring of blood 3HB levels is now available. According to the American Diabetes Association, blood measurement of 3HB "may offer a useful alternative to urine ketone testing." This new technology may provide an opportunity to improve the management of uncontrolled diabetes and sick days in an attempt to reduce the human and economic burden of DKA.

Ketone bodies: a review of physiology, pathophysiology and application of monitoring to diabetes

Ketone bodies are produced by the liver and used peripherally as an energy source when glucose is not readily available. The two main ketone bodies are acetoacetate (AcAc) and 3-beta-hydroxybutyrate (3HB), while acetone is the third, and least abundant, ketone body. Ketones are always present in the blood and their levels increase during fasting and prolonged exercise. They are also found in the blood of neonates and pregnant women. Diabetes is the most common pathological cause of elevated blood ketones. In diabetic ketoacidosis (DKA), high levels of ketones are produced in response to low insulin levels and high levels of counterregulatory hormones. In acute DKA, the ketone body ratio (3HB:AcAc) rises from normal (1:1) to as high as 10:1. In response to insulin therapy, 3HB levels commonly decrease long before AcAc levels. The frequently employed nitroprusside test only detects AcAc in blood and urine. This test is inconvenient, does not assess the best indicator of ketone body levels (3HB), provides only a semiquantitative assessment of ketone levels and is associated with false-positive results. Recently, inexpensive quantitative tests of 3HB levels have become available for use with small blood samples (5-25 microl). These tests offer new options for monitoring and treating diabetes and other states characterized by the abnormal metabolism of ketone bodies.

Urine ketone dip test as a screen for ketonemia in diabetic ketoacidosis and ketosis in the emergency department

STUDY OBJECTIVE

To determine the sensitivity of the urine ketone dip test (UKDT) for the detection of ketonemia in patients with diabetic ketoacidosis (DKA) and diabetic ketosis (DK) in the ED.

METHODS

We conducted a retrospective chart review in the ED of an urban, university-affiliated county teaching hospital. The study population comprised patients seen in the ED during 1994 and 1995 with a discharge diagnosis of DKA or DK and underwent urinalysis within 4 hours of the initial serum electrolyte and ketone determinations. We calculated test sensitivity, along with 95% confidence intervals (CIs).

RESULTS

One hundred forty-eight patients with 223 occurrences diagnosed as DKA or DK were seen in the ED during the study period. One hundred fourteen patients with 146 occurrences of DKA or DK met all inclusion criteria; these patients made up the study group. There were 99 cases of DKA and 47 cases of DK. The sensitivity of the UKDT for the detection of ketonemia in all patients with DKA or DK was 97% (95% CI, 94% to 99%). In the subgroup of patients with DKA, the sensitivity of the UK was 97% (95% CI, 92% to 99%). For patients with DK, the sensitivity of the UK was 98% (95% CI, 89% to 99%).

CONCLUSION

The UKDT is highly sensitive for the presence of serum ketones in patients with DKA and DK. Prospective study is suggested to determine the specificity of the UKDT in this application and to validate its use as a screening tool for the detection of ketonemia in DKA and DK.

New whole blood analyzers and their impact on cardiac and critical care

Miniaturized whole blood biosensors, patient-focused hospitals, and rising expectations of patients and physicians are shifting laboratory diagnostics to the point of care. Expanding transplantation and intensive care are increasing the need for rapid test results. Whole blood analysis improves accuracy, eliminates centrifugation, reduces response time, and conserves blood volume. Several hand-held, and over 20 portable or transportable whole blood instruments are now available. Criteria for instrument evaluation include test menus, point-of-care features, analysis time, on-site performance, and information integration. Whole blood analyzers measure several vital indicators (pO2, pCO2, pH, hematocrit, K+, Ca2+, Na+, Cl-, glucose, and lactate) simultaneously in less than 2 min with less than 200 microliters of whole blood. Other in vitro tests are available (Mg2+, osmolality, CO2 content, urea nitrogen, beta-hydroxybutyrate, hemoglobin, coagulation) or under development (HCO3- phosphorus). Some can be monitored in vivo (O2 saturation, pO2, pCO2, pH, glucose) or ex vivo. The clinical impact is demonstrated by ionized calcium, now established in importance for cardiac and neurologic problems, and ionized magnesium, a promising new measurement. The hybrid laboratory (a composite of conventional clinical laboratory and patient-focused testing), performance maps, and quality paths facilitate implementation of new whole blood analyzers for optimal support of cardiac and critical care, and improved patient outcomes (prospects).

The effects of different plasma insulin concentrations on lipolytic and ketogenic responses to epinephrine in normal and type 1 (insulin-dependent) diabetic humans

This study was performed to verify: (1) the ability of different insulin concentrations to restrict the lipolytic and ketogenic responses to exogenous epinephrine administration; (2) whether the ability of insulin to suppress the lipolytic and ketogenic responses during epinephrine administration is impaired in Type 1 (insulin-dependent) diabetic patients. Each subject was infused on separate occasions with insulin at rates of 0.2, 0.4, and 0.8 mU.kg-1.min-1 while normoglycaemic. To avoid indirect adrenergic effects on endocrine pancreas secretions, the so-called "islet clamp" technique was used. Rates of appearance of palmitic acid, acetoacetate, and 3-hydroxybutyrate were simultaneously measured with an infusion of 13C-labelled homologous tracers. After a baseline observation period epinephrine was exogenously administered at a rate of 16 ng.kg-1.min-1. At low insulin levels (20 microU/ml) the lipolytic response of comparable magnitude was detected in normal and Type 1 diabetic patients. However, the ketogenic response was significantly higher in Type 1 diabetic patients. During epinephrine administration, similar plasma glucose increments were observed in the two groups (from 4.74 +/- 0.53 to 7.16 +/- 0.77 mmol/l (p less than 0.05) in Type 1 diabetic patients and from 4.94 +/- 0.20 to 7.11 +/- 0.38 mmol/l (p less than 0.05) in normal subjects, respectively). At intermediate insulin levels (35 microU/ml) no significant differences were found between Type 1 diabetic patients and normal subjects, whereas plasma glucose levels rose from 4.98 +/- 0.30 to 6.27 +/- 0.66 mmol/l (p less than 0.05) in Type 1 diabetic patients, and from 5.05 +/- 0.13 to 6.61 +/- 0.22 mmol/l (p less than 0.05) in normal subjects. At high insulin levels (70 microU/ml) the lipolytic response was detectable only in Type 1 diabetic patients; the ketogenic response was reduced in both groups. During the third clamp, a significant rise in plasma glucose concentration during epinephrine infusion was observed in both groups. In conclusion this study shows that at low insulin levels Type 1 diabetic patients show an increased ketogenic response to epinephrine, despite their normal nonesterified fatty acid response. Instead, high insulin levels are able to restrict the ketogenic response to epinephrine in both normal and Type 1 diabetic subjects, although there is a still detectable lipolytic response in the latter. In the presence of plasma free insulin levels that completely restrict the ketogenic response in the same group, there is still a distinct glycaemic response. Plasma insulin levels in Type 1 diabetic patients are a major determinant of the metabolic response to epinephrine.

Diabetic ketoacidosis

In the past decade, considerable advances have occurred in our understanding of the pathophysiology of this disorder, its metabolic sequelae, and its management, particularly with respect to continuous low-dose insulin infusion and the potential benefits of phosphate. This article reviews these advances as they pertain to children.