Hormone and metabolic profiles in children and adolescents with type I diabetes mellitus

Diurnal concentrations of glucose, the major regulatory hormones, and selected biochemistries were measured serially throughout a 25-h period in 38 healthy type I diabetic patients, 25 patients with acute ketoacidosis, and 20 normal subjects. Poor glucose control, meal intolerance, and hypercortisolemia were the dominant abnormalities in the healthy diabetic subjects. Ketonemia due to elevated plasma beta-hydroxybutyrate concentrations without ketonuria (nitroprusside reaction) was a frequent finding in a group of poorly controlled diabetic subjects. In the patients with acute ketoacidosis, the dominant abnormalities were overproduction of epinephrine and cortisol. High glucagon and growth hormone concentrations were documented in about one-half of these patients. We conclude that (1) the hyperglycemia, meal intolerance, and abnormal ketone body metabolism seen in these patients are caused by inadequacies in their insulin regimens; (2) ketone body underutilization contributes to diabetic ketosis; (3) epinephrine and cortisol overproduction are important components of acute ketoacidosis; and (4) the complex hormone-metabolic interactions in type I diabetes can best be explained by a multihormonal hypothesis with the primary defect being loss of beta-cell function.

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

Plasma beta-hydroxybutyrate (beta-OHB) concentrations and simultaneous urine tests for ketonuria (nitroprusside reaction) were evaluated every 4 h throughout a 24-h study in 10 healthy insulin-dependent diabetics who had poor control based on home urine tests and elevated hemoglobin A1C. Concurrent measurements of the major carbohydrate regulatory hormones were made in the diabetic group and in a control population of 20 age-matched subjects. In the diabetics, 73% of the beta-OHB measurements were elevated. Only 43% of the abnormal beta-OHB values were associated with ketonuria. The diabetic subjects also showed exaggerated diurnal patterns for plasma beta-OHB and cortisol. There were no significant differences for the other regulatory hormones in the diabetic and normal groups. We conclude that 1) abnormal plasma beta-OHB levels without ketonuria are prevalent in poorly controlled diabetics; 2) negative nitroprusside tests for ketonuria underestimate the presence of ketonemia due to increased beta-OHB concentrations; 3) both insulin deficiency and glucocorticoid excess may influence ketone body metabolism in insulin-dependent diabetic patients.

Gastric emptying in prematures of isocaloric feedings with differing osmolalities

The role of osmolar load in the regulation of gastric emptying time was studied in 10 healthy premature infants. Two isocaloric infant feedings of similar composition with mean osmolalities of 279 and 448 mOsm/kg were compared. Emptying was studied over 120 min by the double sampling marker dilution technique and by a single aspiration of the feeding at 30 min. Similar gastric emptying times were noted for both formulas with approximately half of the initial gastric contents remaining at 30 min. The secretory response to the two meals during the first 30 min after feeding was compared by measuring the secretions present in the stomach during that time. The mean secretory response to the feedings did not differ significantly and was less than 2.5 ml in both cases. In general, a biphasic pattern of gastric emptying with a rapid early emptying phase was noted with both feedings. This study, therefore, provides evidence that when isocaloric feedings with similar composition are used, osmolar load does not play a significant role in the regulation of gastric emptying in premature infants. This study also demonstrates that differences in osmolality do not significantly affect the secretory response to a meal in the stomach of the premature infant.

Improved method for determining erythrocyte creatine by the diacetyl-alpha-naphthol reaction: elimination of endogenous glutathione interference

We describe a simple, accurate, and reproducible method for determining erythrocyte creatine. The method is free from glutathione inhibition and is adaptable to use with standard spectrophotometers as well as centrifugal analyzers. A clear filtrate, essentially free of protein, hemoglobin, and glutathione, is prepared from 0.1 mL of packed erythrocytes by treatment with Ba(OH)2 and ZnSO4, then reacted with diacetyl-alpha-naphthol. The standard curve for this method is linear from 10 to 500 mg/L. We show that endogenous sulfhydryl species such as erythrocyte glutathione will interfere with the creatine-diacetyl-alpha-naphthol reaction. This observation confirmed a suspicion of underestimation of erythrocyte creatine by the method of Griffiths (Clin. Chim. Acta 9: 210, 1964). Added p-chloromercuribenzoic acid did not completely eliminate this inhibition. In the present method these interfering sulfhydryl species are eliminated from the reaction mixture, thus obviating the need for p-chloromercuribenzoic acid and dialysis. The reference interval for this method is 42-80 mg/L.

Improved method for determining erythrocyte creatine by the diacetyl-alpha-naphthol reaction: elimination of endogenous glutathione interference

We describe a simple, accurate, and reproducible method for determining erythrocyte creatine. The method is free from glutathione inhibition and is adaptable to use with standard spectrophotometers as well as centrifugal analyzers. A clear filtrate, essentially free of protein, hemoglobin, and glutathione, is prepared from 0.1 mL of packed erythrocytes by treatment with Ba(OH)2 and ZnSO4, then reacted with diacetyl-alpha-naphthol. The standard curve for this method is linear from 10 to 500 mg/L. We show that endogenous sulfhydryl species such as erythrocyte glutathione will interfere with the creatine-diacetyl-alpha-naphthol reaction. This observation confirmed a suspicion of underestimation of erythrocyte creatine by the method of Griffiths (Clin. Chim. Acta 9: 210, 1964). Added p-chloromercuribenzoic acid did not completely eliminate this inhibition. In the present method these interfering sulfhydryl species are eliminated from the reaction mixture, thus obviating the need for p-chloromercuribenzoic acid and dialysis. The reference interval for this method is 42-80 mg/L.

Direct, fixed-time kinetic assays for beta-hydroxybutyrate and acetoacetate with a centrifugal analyzer or a computer-backed spectrophotometer

In the course of studying the control of blood glucose in juvenile onset diabetics, we developed convenient methods for determining beta-hydroxybutyrate and acetoacetate. Here we describe fixed-time, enzymic, reaction-rate procedures for directly measuring these organic acids with a centrifugal analyzer (Rotochem IIA/36) or a computer-backed spectrophotometer (Gilford 102 system). In either case, the method requires only 20 micro L of plasma; is rapid, accurate, and precise; and analytical recovery is quantitative. Data are presented comparing results obtained with both instruments. Metabolic acidosis can be rapidly assessed and monitored with these methods, as illustrated by an example.

Direct, fixed-time kinetic assays for beta-hydroxybutyrate and acetoacetate with a centrifugal analyzer or a computer-backed spectrophotometer

In the course of studying the control of blood glucose in juvenile onset diabetics, we developed convenient methods for determining beta-hydroxybutyrate and acetoacetate. Here we describe fixed-time, enzymic, reaction-rate procedures for directly measuring these organic acids with a centrifugal analyzer (Rotochem IIA/36) or a computer-backed spectrophotometer (Gilford 102 system). In either case, the method requires only 20 micro L of plasma; is rapid, accurate, and precise; and analytical recovery is quantitative. Data are presented comparing results obtained with both instruments. Metabolic acidosis can be rapidly assessed and monitored with these methods, as illustrated by an example.

Mechanism of interference by hemoglobin in the determination of total bilirubin. I. Method of Malloy-Evelyn

Oxyhemoglobin is the species of hemoglobin in erythrocyte hemolysates that inhibits the diazo reaction. Ferric hemoglobin derivatives and species with relatively low molecular mass do not interfere. Conversion of oxyhemoglobin to acid hematin under assay reaction conditions is associated with rapid destruction of bilirubin, which accounts for the diazo reaction error. The most probable mechanism for this destruction of bilirubin is an oxidative reaction involving H2O2, formed in the oxidation of hemoglobin, and acid hematin acting as a pseudoperoxidase. We could find no evidence for other mechanisms of interference such as spectral error or azobilirubin destruction. Addition of potassium iodide, 4.0 mmol/L final concentration in the reaction mixture, eliminates interference from hemoglobin added to give concentrations as great as 10 g/L. It also eliminated the effects of hemolysis in the method of Ertingshausen et al. (Clin. Chem. 19: 1366, 1973), in which ethylene glycol is used as the accelerator.

Mechanism of interference by hemoglobin in the determination of total bilirubin. I. Method of Malloy-Evelyn

Oxyhemoglobin is the species of hemoglobin in erythrocyte hemolysates that inhibits the diazo reaction. Ferric hemoglobin derivatives and species with relatively low molecular mass do not interfere. Conversion of oxyhemoglobin to acid hematin under assay reaction conditions is associated with rapid destruction of bilirubin, which accounts for the diazo reaction error. The most probable mechanism for this destruction of bilirubin is an oxidative reaction involving H2O2, formed in the oxidation of hemoglobin, and acid hematin acting as a pseudoperoxidase. We could find no evidence for other mechanisms of interference such as spectral error or azobilirubin destruction. Addition of potassium iodide, 4.0 mmol/L final concentration in the reaction mixture, eliminates interference from hemoglobin added to give concentrations as great as 10 g/L. It also eliminated the effects of hemolysis in the method of Ertingshausen et al. (Clin. Chem. 19: 1366, 1973), in which ethylene glycol is used as the accelerator.

Mechanism of interference by hemoglobin in the determination of total bilirubin. II. Method of Jendrassik-Grof

Oxyhemoglobin in erythrocyte hemolysates interferes with the Jendrassik-Grof assay. Destruction of azobilirubin occurs when oxyhemoglobin is oxidized to methemoglobin during diazotization or to alkaline hematin with addition of alkaline tartrate. The most probable mechanism is by oxidation with an agent such as hydrogen peroxide or a related species resulting from hemoglobin oxidation. Methemoglobin also appears to cause some destruction of azobilirubin during diazotization. Methemoglobin forms during diazotization because of reactions of oxyhemoglobin with both diazo reagent and nitrite ion. Formation of methemoglobin is, therefore, more rapid in the test than in the blank mixture and, under reaction conditions, its absorbance is less than that of oxyhemoglobin. This results in spectral interference when neutral azobilirubin is assayed. Alkaline tartrate abolishes this spectral error by causing rapid formation of alkaline hematin in both test and blank.

Mechanism of interference by hemoglobin in the determination of total bilirubin. II. Method of Jendrassik-Grof

Oxyhemoglobin in erythrocyte hemolysates interferes with the Jendrassik-Grof assay. Destruction of azobilirubin occurs when oxyhemoglobin is oxidized to methemoglobin during diazotization or to alkaline hematin with addition of alkaline tartrate. The most probable mechanism is by oxidation with an agent such as hydrogen peroxide or a related species resulting from hemoglobin oxidation. Methemoglobin also appears to cause some destruction of azobilirubin during diazotization. Methemoglobin forms during diazotization because of reactions of oxyhemoglobin with both diazo reagent and nitrite ion. Formation of methemoglobin is, therefore, more rapid in the test than in the blank mixture and, under reaction conditions, its absorbance is less than that of oxyhemoglobin. This results in spectral interference when neutral azobilirubin is assayed. Alkaline tartrate abolishes this spectral error by causing rapid formation of alkaline hematin in both test and blank.

Iron toxicity screening

Fischer's method for rapid detection of acute iron toxicity is modified to suit pediatric cases. TPTZ (2,4,6-tripyridyl-s-triazine) is the chromogen of choice since in a small volume of serum slight to moderate hemolysis can cause a false positive result bathophenanthroline. Ordinary labware is amenable to this simplified procedure.

Fixed-time kinetic assay of plasma ammonia, with NADPH as cofactor, with a centrifugal analyzer

We describe a fixed-time, enzymatic, reaction-rate procedure for determining plasma ammonia with a centrifugal analyzer (Rotochem IIA/36; American Instrument Co., silver Spring, MD 20910), with NADPH as cofactor. The reaction is based on that of da Fonseca-Wollheim's modification [J. Clin. Chem. Clin. Biochem. 11, 421 (1973)] of the Kirstein reaction, which depends on the catalytic amination of alpha-ketoglutarate by the action of glutamate dehydrogenase with NADPH as the cofactor instead of NADH. Use of NADPH minimizes interference from endogenous reactions such as that between lactate dehydrogenase and pyruvate. This method permits shortened preincubation time and thus improves both specificity and precision. This assay requires 100 microliter of freshly collected heparinized plasma, gives quantitative analytical recovery, and the standard curve is linear to 430 mumol/L. Data are presented comparing results with those by two other enzymatic ammonia procedures.

Fixed-time kinetic assay of plasma ammonia, with NADPH as cofactor, with a centrifugal analyzer

We describe a fixed-time, enzymatic, reaction-rate procedure for determining plasma ammonia with a centrifugal analyzer (Rotochem IIA/36; American Instrument Co., silver Spring, MD 20910), with NADPH as cofactor. The reaction is based on that of da Fonseca-Wollheim's modification [J. Clin. Chem. Clin. Biochem. 11, 421 (1973)] of the Kirstein reaction, which depends on the catalytic amination of alpha-ketoglutarate by the action of glutamate dehydrogenase with NADPH as the cofactor instead of NADH. Use of NADPH minimizes interference from endogenous reactions such as that between lactate dehydrogenase and pyruvate. This method permits shortened preincubation time and thus improves both specificity and precision. This assay requires 100 microliter of freshly collected heparinized plasma, gives quantitative analytical recovery, and the standard curve is linear to 430 mumol/L. Data are presented comparing results with those by two other enzymatic ammonia procedures.

A useful method for predicting creatinine clearance in children

A practical method for predicting creatinine clearance for pediatric patients from serum creatinine concentration and patient age is presented. Creatinine excretion rate (ER) can be predicted from the patient's age, in years, by the formula: ER = (0.035 X age) + 0.236. Using the predicted excretion rate and serum creatinine concentration, creatinine clearance can be predicted. There was good correlation (r = 0.90) between predicted and observed creatinine clearances in 101 subjects with various degrees of renal impairment. This method allows renal function to be rapidly estimated.

A useful method for predicting creatinine clearance in children

A practical method for predicting creatinine clearance for pediatric patients from serum creatinine concentration and patient age is presented. Creatinine excretion rate (ER) can be predicted from the patient's age, in years, by the formula: ER = (0.035 X age) + 0.236. Using the predicted excretion rate and serum creatinine concentration, creatinine clearance can be predicted. There was good correlation (r = 0.90) between predicted and observed creatinine clearances in 101 subjects with various degrees of renal impairment. This method allows renal function to be rapidly estimated.