Glucose Information and Courses from MediaLab, Inc.

The following table lists some of the chemicals present in CSF, and their concentrations: ChemicalLevel sodium 136.0 - 150.0 m Eq/L potassium 2.3 - 2.7 m Eq/L magnesium2.4 - 3.0 m Eq/Lprotein2 - 4 mg/dL (normally diffuses across blood-brain barrier) glucose 45.0 - 60.0 mg/dL calcium2.1 - 2.7 m Eq/dLcholesterolpresent in small amounts creatinine 0.5 - 1.2 mg/dL lactic acid dehyrdogenase (LDH) present in small amounts phosphorus (inorganic)1.0 - 2.0 mg/dLurea6.0 - 16.0 mg/dL uric acid 0.5 - 3.0 mg/dL

Reasons for acidic urine pH include: a high-meat diet, respiratory/metabolic acidosis, and hypochloridemia. A urine with a high concentration of glucose may also have a lower pH. An alkaline pH may be the result of a vegetarian diet, respiratory/metabolic alkalosis, or a bacterial infection caused by urease-producing bacteria. Urine that contains bacteria can become more alkaline if the specimen remains at room temperature for an extended period of time.

Individuals with diabetes mellitus may excrete small amounts of protein in the urine which may signal the beginning of reduced glomerular filtration. Stabilizing the blood glucose level at this time may delay progression of diabetic nephropathy. Women in the last month of pregnancy may develop proteinuria as the first sign of impending eclampsia. Eclampsia is the gravest form of toxemia of pregnancy. The presence of protein in this situation must be evaluated by the physician in conjunction with other clinical symptoms.Benign transient proteinuria may be the result of: exposure to cold, strenuous exercise, dehydration, and/or high fever. Benign transient proteinuria may also occur during the acute phase of a severe illness.

False negative results occur when elements present in the urine interfere with either the enzymatic reaction or prevent the oxidation of potassium iodide. Examples of such substances include: large quantities of ketones aspirin ascorbic acid > 50 mg/dL with some reagent strips levadopa 5-hydroxyindoleacetic acid homogentisic acid sodium fluoride ( a preservative)A specific gravity higher than 1.020 may lower glucose reagent sensitivity, especially in the presence of a high urine pH. Exposing reagent strips to excess humidity may also reduce glucose reagent reactivity.Check the package insert of the reagent strips used in your laboratory for interfering substances that may affect glucose results.

In the healthy individual, almost all of the glucose filtered by the renal glomerulus is reabsorbed in the proximal convoluted tubule. The amount of glucose reabsorbed by the proximal tubule is determined by the body's need to maintain a sufficient level of glucose in the blood. If the concentration of blood glucose becomes too high (160-180 mg/dL), the tubules no longer reabsorb glucose, allowing it to pass through into the urine. It is important to note that glucose may appear in the urine of healthy individuals after consuming a meal that is high in glucose. Fasting prior to providing a sample for screening eliminates this problem.

When the body breaks down fat for energy, three intermediate products are formed. These products, collectively referred to as ketones, are acetone, acetoacetic acid, and beta-hydroxybutyric acid. Normally, the body gets the energy it needs from carbohydrates in the diet. However, stored fat is broken down and ketones are produced and appear in the urine if the diet does not contain enough carbohydrate to supply the body with glucose for energy or if the body cannot use glucose properly.

Specific gravity measured with the reagent strip method correlates well with gravimetric measurement, and, unlike the gravimetric or refractometer methods, does not need to be corrected for glucose or protein. Cloudy/turbid urines do not need to be clarified before measuring specific gravity with the reagent strip method. It is the recommended method for determining specific gravity if a urine specimen contains x-ray contrast media or plasma expanders. Alkaline urine can affect the indicator system and lower the specific gravity result on the reagent pad. If the result is being read visually, it is recommended that .005 be added to the result when the pH is alkaline. Most dipstick readers, however, will automatically adjust the specific gravity reading for pH. A specific gravity reading higher than the reagent strip range would need to be measured by another method, and may require dilution.

Urine reagent strips are normally adequate for urine screening, but occasionally, it may be necessary to perform a secondary procedure to ensure the accuracy of the test result. Confirmatory or secondary procedures are usually performed for one or more of these reasons: To confirm a result that has been obtained on the reagent strip. To obtain a result from a highly pigmented urine that masks the result on the reagent strip. To test for a specific analyte (or analytes) that are not included in the specificity of the reagent strip test. For example, the glucose reagent strip test is specific for glucose, but you want to test for other reducing substances.

Although glucose is the sugar most commonly tested for in urine, normal human urine can contain small amounts of galactose, lactose, fructose, xylose, and other pentoses. Galactosuria, an abnormal amount of galactose in the urine, occurs in infants with a congenital metabolic defect. Lactose may be found in the urine of nursing women and during late pregnancy. All of these sugars, including glucose, are reducing substances.

There are two basic types of tests that are used to screen or monitor glycosuria -- copper reduction tests and enzyme tests. Most enzyme tests use the enzyme glucose oxidase impregnated on a dipstick along with a chromagen, and are specific for detecting only glucose. The copper reduction tests, however, detect any reducing substance. Clinitest® uses the classic Benedict’s copper reduction reaction. Any reducing substances present in the urine will react with the copper sulfate reagent, and the blue cupric sulfate is subsequently reduced to cuprous oxide. The resultant color change from blue through green to orange is proportional to the amount of reducing substance in the urine sample.

It is important to test for urinary (and plasma or serum) ketones when any patient shows a greater than normal excretion of sugar or reducing substances. Screening for ketonuria is useful in following the effects of treatment for diabetes and in judging the severity of acidosis. Large amounts of ketones will appear in the urine before serum ketone levels are elevated.

Eikenella corrodens (E) belongs to the HACEK group of miscellaneous gram-negative bacilli which includes Haemophilus aphrophilus (H), Actinobacillus actinomycetemcometans (A), Cardiobacterium hominis (C) and Kingella kingae (K).Cytochrome oxidase and catalase are two rapid tests that help separate the several members of this group.Eikenella corrodens shows cytochrome oxidase activity, but not catalase activity. The positive oxidase reaction separates E. corrodens from Haemophilus aphrophilus and Actinobacillus actinomycetemcomitans, which are both negative.A. actinomycetemcomitans is also catalase positive, an additional characteristic separating it from E. corrodens, which is negative.As Kingella kingae is also oxidase positive and catalase negative, other tests are needed for differentiation. K. kingae produces acid from glucose and maltose (E. corrodens is asaccharolytic).

Newfield RS. Vargas I. Huma Z.: Eikenella corrodens infections. Case report in two adolescent females with IDDM. Diabetes Care. 19:1011-3, 1996OBJECTIVE: To alert physicians caring for patients with diabetes to the microorganism Eikenella corrodens and to discuss the appropriate preventive and therapeutic measures to take against this potentially morbid opportunistic Gram-negative bacilli.CASES: We present two cases of extra-oral E. corrodens infections in adolescent females with IDDM. The first patient had diabetes of 4 years' duration, which was moderately well controlled. Chronic finger biting resulted in a complex felon that evolved gradually and worsened while the patient received cephalexin orally. Delay in seeking further intervention resulted in necrosis of her distal fingertip and nail bed. The second patient had poorly controlled diabetes for 5 years. She developed an acute thigh abscess at an insulin injection site that resolved after drainage and intravenous antibiotics.CONCLUSIONS: E. corrodens commonly inhabits the human oral cavity and becomes a pathogen mostly when host defenses are impaired, causing abscesses and infections that are at times fatal. Patients with IDDM are compromised hosts and with daily microtrauma to their skin via glucose monitoring and insulin injections, are prone to develop E. corrodens infections that can be introduced through oral secretions by licking or biting their skin. Educational efforts aimed at preventing exposure of traumatized skin to oral secretions can minimize the risk of E. corrodens infections in compromised hosts.Early intravenous administration of antibiotics, bearing in mind E. corrodens resistance to clindamycin, metronidazole, and other antibiotics, coupled with prompt surgical intervention, is essential in successfully managing E. corrodens infections.

There are two main types of data that you might encounter.  The first is discrete data, which is a count of whole events, objects or persons.  For example, the number of people with a certain illness is a discrete quantity.The other type of data is continuous data, which is the measure of a quantity such as length, volume, or time, which can occur at any value.  For example, the concentration of glucose in the blood is a continuous quantity.  Even if the instrument you are using rounds off values to whole numbers, these quantities are still continuous.

Table III shows the unsorted raw data that will be used to make a frequency table. Note that the low and high results are highlighted. These data are continuous; however, the testing equipment rounds the data off to the nearest whole number of milligrams.Table IIIConcentration of Serum Glucose (mg/dL) in 130 Hospital Employees 100 83 80 114 100 80 85 81 101 80 95 108 79 81 97 77 84 88 78 86 81 77 98 85 92 105 85 108 90 89 84 94 84 81 82 78 84 82 98 86 87 74 79 104 89 91 85 72 92 90 93 87 90 99 96 110 107 97 84 76 83 80 101 75 84 76 73 86 71 84 70 79 91 86 86 91 87 96 96 97 106 104 65 81 103 83 90 70 80 80 75 82 83 76 81 87 84 86 93 86 103 76 112 102 93 89 67 78 84 82 91 86 82 82 87 89 95 90 73 103 75 113 93 86 77 95 94 99 87 92

Bar charts are preferred for discrete data.  The height of the bar between the "65" and "70" tick marks corresponds to the number of elements in the 65 - 70 class,  etc.Figure 3Frequency of Serum Glucose Levels in 130 Hospital Employees

The frequency polygon resembles a continuous curve, and is therefore appropriate for illustrating continuous data. Instead of bars, the class midpoints are plotted at heights corresponding to the class frequency. The midpoints are then joined by a line.Figure 5Frequency of Serum Glucose Levels in 130 Hospital Employees

Sometimes you will need to analyze data that are in the form of pairs, with one independent variable and one dependent variable in each pair. For example, the data pairs may be ages and weights of children, or hours studied and test scores of students.The best way to represent these data graphically is with a scatterplot: plotting each independent variable as an x-coordinate, and each dependent variable as a y-coordinate. This allows the reader to quickly see if there is a relationship between the two variables, and how strong the relationship is.You may also analyze data that do not occur as pairs, but as single numbers. Examples include the test scores of many students, or the glucose levels of diabetic patients. These data are presented graphically with a frequency distribution.

Coefficient of variation is commonly used as a means of measuring the variability of an instrument. The data are gathered by recording the values for the normal and abnormal controls for each test run. At the end of the month, the standard deviation, mean, and coefficient of variation are calculated. The testing data for a particular instrument might look like this: January February March Normal Control s CV 100.9 2.43 2.41 103.1 2.99 2.90 102.0 2.21 2.17 Abnormal Control s CV 209.5 4.41 2.11 211.6 4.00 1.89 206.8 3.95 1.91 The coefficient of variation stays fairly constant from month to month. If there is a sudden increase, there might be a problem with the method or the equipment.In the clinical laboratory, the use of CV as a measure of relative variability should not be confused with the use of the standard deviation as a measure of absolute variability. For example, support physicians agreed that for accurate patient treatment, the inherent variability in a glucose method should be less than 5 mg/dL. In this case, neither the hexokinase nor the orthotoluidine method is acceptable. It does not matter which is more precise if neither is precise enough to result in adequate patient care.

For example, to find a relationship between glucose concentration and absorbance, we could first plot all the points on a scatterplot. Glucose (mg/dL) Absorbance 50 .10 100 .20 150 .30 200 .40 250 .50 300 .60

Consists of an electrolyte panel, plus: Blood urea nitrogen (BUN), which a measure of renal function. Creatinine (Creat), which also measures renal function Glucose, the most important blood sugar, and Calcium. Run on serum or plasma

Sugars are also dissolved in the plasma. By far the most important is glucose. Blood glucose is increased in diabetes mellitus, and decreased in hypoglycemia.

Collect venous blood for a fasting glucose level.Give the patient a standard dose of glucose, usually in the form of a beverage such as Glucola™ (Allegiance). Always follow your own procedure manual. In general:Give a 50 gram glucose dose to screen pregnant women at 28 weeks for gestational diabetes.Give a 75 gram glucose dose to nonpregnant adults.Give a 100 gram glucose dose to confirm the diagnosis of gestational diabetes.

About 2-3% of women will develop gestational diabetes.Since women with gestational diabetes have a higher risk of losing their baby or having a baby with malformations, diagnosis and treatment of gestational diabetes is important.Pregnant women are screened for gestational diabetes at 28 weeks using a modified glucose tolerance test.Patients are given a 50 gm dose of Glucola, and blood is collected for glucose testing one hour later.If the glucose level is greater than 140 mg/dl, a 3 hour glucose tolerance test is required to confirm the diagnosis of gestational diabetes.

To screen for gestational diabetes, collect blood after one hour.For a standard glucose tolerance test collect blood and urine at 30 minute intervals, for two hours.To confirm gestational diabetes, collect blood every hour for 3 hours.

The mean is simply an average of data points. Let’s say that 100 glucose determinations are performed on a known control sample. If we add all the results together, then divide by the number of results, we get the mean.Significant variations in the mean from day to day may indicate systematic errors.

To illustrate the use of CUSUM in the laboratory, we'll use daily control values for glucose testing.First, we'll list daily control values under "daily results." Then, we'll calculate mean by using formula A. Next, we can find the difference from the mean for each result, and square that result for the two relevant columns. Using all of the squared differences from the mean, we can find the standard deviation using formula B. Using the mean from formula A and the standard deviation calculations from formulas B and C, we can plot our data points on the Levey-Jennings chart. Formula D helps us calculate the coefficient of variation (CV), which expresses SD as a percentage of mean value and is more reliable for comparing precision at different concentration levels. The lower the CV the greater the precision.

For this problem, you may need to work off-line. After you have evaluated the data on the following page, return to the course and answer the accompanying questions. Problem You are the only full-time employee at a small clinic's laboratory. You use an assayed control for your glucose determinations. The manufacturer's printed values for the present lot number are: Level 1 ControlMean: 72 mg/dLStandard deviation: +/- 2 mg/dLLevel 2 ControlMean: 281 mg/dLStandard deviation: +/- 12 mg/dLThe table on the next page shows that control results for the first twelve days of testing for the month. Plot your QC results on a Levey-Jennings chart and evaluate your data.

Schistocyte is a general term for a fragmented red blood cell that may assume various shapes, some with horn-like projections (keratocytes), triangle-forms (triangulocytes), and helmet shapes, as illustrated in the upper photograph. Schistocytes are formed when erythrocytes are forced through a vessel blocked with interlacing fibrin strands and the red cells are sliced into fragments. True schistocytes are devoid of central pallor. These damaged cells continue to circulate while healing their torn edges. Finally, they are removed by the spleen. Bite cells (lower photograph) appear when an abnormal hemoglobin aggregate (Heinz body) is nibbled out of a red cell's cytoplasm by the spleen leaving a bitten apple appearance. Glucose 6-PD deficiency secondary to chemical poisoning or injury by oxidant drugs are settings for Heinz body formation, and the telltale bite cells remain as evidence. Hemolytic anemia associated with severe liver disease is another setting where bite cells are formed.

The results are abnormal. The presence of glucose is not a normal finding. However, the two glucose methods correlate well with each other.The specific gravity does not correlate well with the glucose. A large amount of glucose should elevate the urine specific gravity. The specific gravity result should therefore be rechecked before reporting. The presence of 3+ bacteria, does not correlate well with scant white cells and lack of turbidity. The technologist should question whether the specimen was held at room temperature for a protracted period prior to examination.