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Cerebrospinal fluid glucose measurements with Dextrostix and reflectance meter
BRIEF C L I N I C A L A N D LABORATORY OBSERVATIONS
Articles in this section should require less than three JOURNALpages: text, less than 1,000 words; 1 or 2 illustrations and/or tables; up to 10 references.
Cerebrospinal fluid glucose measurements with Dextrostix and reflectance meter Duna Penn, M.D.,* Paul R. Williams, M.D., and Robin M. Adair, R o y a l Oak, Mich.
DEXTROSTIX reagent strip determinations Of whole blood glucose by reflectometer have been shown to have excellent correlation with conventional laboratory techniques over various concentrations (10 to 400 mg/dl). 1-~ This method of estimation of blood glucose has gained wide clinical acceptance because it is rapid, accurate, and requires small samples of blood. Attempts to utilize the technique with cerebrospinal fluid, however, have been unsatisfactory. 67 Suggested modifications have proved to be cumbersomes We describe here a convenient modification of the Dextrostix technique that provides a rapid and accurate estimation of glucose concentration in CSF.
METHODS Pooled CSF (from adults and children) was divided into multiple aliquots. Standardized glucose solutions were added to vary the concentrations from 6 to 260 mg/dl. The effect of protein on Dextrostix determinations of glucose was studied by adding varying amounts of Plasmanate to adjust concentrations from 80 to 1,000 mg/ dl. In addition, 54 random CSF samples were analyzed Without manipulation of glucose (3 to 217 mg/dl) or protein concentration (11 to 220 mg/dl). From the Department of Pediatrics, William Beaumont Hospital. *Reprint address William Beaumont Hospital, Royal Oak, MI 48072.
Glucose determinations by Dextrostix (Ames Eyetone Reflectometer) and by glucose analyzer (Beckman Glucose Analyzer) methods were performed on samples in duplicate. Total protein was measured by a turbidimetric procedure using trichloroacetic acid (DuPont Automatic Clinical Analyzer). Dextrostix consists Of an active area impregnated with a glucose oxidase/peroxidase/chromagert system and coated with a semipermeable membrane to prevent access of red blood cells. This membrane might be expected to exhibit different permeabilities to various solutions. The active portion of the Dextrostix was completely covered by CSF. All Dextrostix determinations were performed at room temperature. Aliquots from each sample were tested at 45 seconds (Dextrostix-45) and repeated at 60 seconds (Dextrostix-60). A stopwatch was used for accurate timing. The enzyme strip was washed with distilled water. It was then blotted dry and immediately inserted into the reflectometer. The instrument was left on continuously and calibrated frequently using manufacturer's standards representing 50 and 400 mg/dl glucose concentrations. Abbreviation used CSF: cerebrospinal fluid
[
Results obtained by the Beckman Glucose Analyzer were considered the reference values. Data Were analyzed by the Student's t test, paired t-test, and simple linear regression. RESULTS Fig. 1A demonstrates the close correlation between the Dextrostix-45 measurements and glucose values determined by the reference glucose oxidase method. There were no significant differences between the two methods over the glucose concentration range 10 to 160 mg/dl. Some deviation was noted at higher glucose levels. In Contrast, Fig. 1B demonstrates the correlation between the Dextrostix-60 measurements and the reference values. Despite an excellent correlation coefficient
The Journal of P E D I A T R I C S
771
772
Brief clinical and laboratory' observations
The Journal q[ Pediatrics May 1977
i
240 220. DEXTROSTIX-45't'ILE,M. DEXTRO6TIX-60tS.E.M. - - IDEAL CURVE + +
200"
"[
180.
::]// ----p
0
......
25
I 50
9-~
80~
I.... 75
~
........ ] -
100
125
,ol
" k 150
.iFo
/
~176 [
20
40
60
8~0
' 100
120
OJueose (mg/dl) Beckman Glucose Analyzer
140
160
(r = 0.995), there was significant deviation from the ideal curve. In Fig. 2, all reference glucose determinations were grouped into 10 m g / d l increments. Each locus on the abscissa represents the mean (_+ SEM) on these increments. Loci on the ordinate represent the mean ( • SEM) of Dextrostix determinations corresponding to the reference points included in each 10 m g / d l increments, The close correlation of Dextrostix-45 measurements to the reference method is evident in contrast to the significant deviation of the Dextrostix-60 value from the ideal
y
/.:
50-~
/ /Ny=X
"
0
Fig. 2. Correlation between mean glucose concentrations _+ standard error of the mean obtained by Dextrostix following either 45 or 60 seconds of incubation and the reference glucose oxidase method9 All reference glucose determinations were grouped into 10 mg/dl increments. Each locus on the abscissa represents the mean (_+ SEM) of these increments. Loci on the ordinate represent the mean ( _+ SEM) of Dextrostix determinations corresponding to the reference points included in.each 10 mg/dt increment.
/ '. /
+/
20O l / "
;:0.3,;;-
I
'i' ,/
Fig. IA. Correlation between results obtained by Dextrostix following 45-second incubation and the reference glucose oxidase method; (y = x) represents the ideal curve.
o
§
~ 100
Glucose ( m g / d l ) Beckman Glucose Analyzer
m
L,o
f
: : / ~
curve.
25 II
0
/
"~ " "
25
I
'I 50
I 75
I 100
i 125
I 150
Glucose ( m g / d l ) Beckman Glucose Analyzer Fig. lB. Correlation between results obtained by Dextrostix following 60-second incubation and the reference glucose oxidase method; (y = x) represents the ideal curve
DISCUSSION Rapid and accurate estimation of C S F glucose concentration may be helpful in the investigation of meningitis 9 A blood glucose determination performed at the same time would aid in differentiating between hypoglycemia and meningitis 9 Although blood glucose determinations have been shown to be accurate in other studies?-:' previous attempts to use Dextrostix in the
Volume 90 Number 5
Brief clinical and laboratory observations
routine manner with C S F have generally overestimated glucose v a l u e s . " : Swietek and associates ~ modified the technique to improve the accuracy of CSF determinations with Dextrostix. Unfortunately, their method was time consuming and cumbersome. Accuracy of this modification of the Dextrostix technique is dependent upon several critical factors including: quality control of the Dextrostix reagent sirips; frequent calibration of the reflectometer (at least twice daily); adequate sample size to completely cover the tip of the reagent strip; and strict adherence to the 45-second incubation period. Dextrostix-45 values were consistent with those obtained by the reference glucose oxidase method over a glucose concentration range of 10 to 160 m g / d l and a protein range of 11 to 1,000 m g / d l . These values are well within the scope of those c o m m o n l y encountered in CSF analysis. Therefore, it is suggested that the use of Dextrostix with a 45-second incubation period and the reflectometer may provide a rapid and accurate bedside estimation of C S F glucose.
Coexistent hemophilia A and idiopathic thrombocytopenic purpura Marilyn A. Hruby, M.D., Chicago, Ill.
THE PRESENCE o f unrelated congenital or acquired hematologic disorders in patients with factor VIII deficient hemophilia has previously been reported. These associated conditions have included congenital factor V deficiency,' acute leukemia, ~ an abnormal fibrinogen,:' hereditary hemorrhagic telangiectasia/ a functional abnormality of the platelets,:'." and thrombocytopenia secondary to hypersplenism5 In this report we present the findings of two unusual cases of chronic idiopathic thrombocytopenia occurring in hemophilic patients, with a successful outcome following splenectomy in one case. From the Department of Pediatrics, Northwestern University and Children's Memorial Hospital *Reprint address: Children's Memorial Hospital 2300 Children's Plaza Chicago, 1L 60614.
7 73
REFERENCES
1. Jarrett R J, Keen H, and Hardwick C: "Instant" blood sugar measurement using Dextrostix and a reflectance meter, Diabetes 19:724, 1970. 2. Mazzaferri EL, Skillman TG, Lanese RR, and Keller MP: Use of test strips with colour meter to measure blood glucose, Lancet 1:331, 1970. 3. Scherstein B, Kuhl C, Hollender A, and Ekman R: Blood glucose measurements with Dextrostix and new reflectance meter, Br Med J 3:387, i974. 4. Ente G, Klein SW, and Paraswanath BS: Evaluation of a direct-reading reflectometer for neonatal hypoglycemia screening, Am J Clin Pathol 61:612, 1974. 5. Frantz ID, Medina G, and Taeusch HW: Correlation of Dextrostix values with true glucose in the range less than 50 mg/dl, J PEDIATR87:417, 1975. 6. Marks V, and Dawson A: Rapid stick method for determining blood-glucose concentration, Br Med J 1:293, 1965. 7. Swietek KR, Luebben G, and Cornblath M: Screening method for determining glucose in blood and cerebrospinal fluid, Am J Dis Child 117:672, 1969.
CASE REPORTS Case 1. A 19-year-old Mexican-American boy had a history of easy bruising, hematoma formation, and prolonged bleeding from minor lacerations beginning at two years of age, which led to a diagnosis of mild factor VIII deficient hemophilia (t0% factor VIII). A younger brother was found to be similarly affected. The patient was first noted to be thrombocytopenic in 1964 at the age of seven years when epistaxis appeared and bruising increased in frequency. The platelet count at that time was 27,000/mmL A diagnosis of acute idiopathic thrombocytopenic purpura was made on the basis of history, physical findings, and bone marrow examination. The platelet count returned to normal spontaneously within a few weeks. Over the next three and one-half years the patient was noted to be moderately thrombocytopenic on several occasions. Because of his asymptomatic course, no therapy was instituted. Platelet counts obtained from all family members were within the normal range. In June, 1973, he was admitted to the hospital with findings suggestive of a retroperitoneal hemorrhage. Treatment with daily infusions of cryoprecipitate or factor VIII concentrate resulted in a complete recovery. Two weeks after discharge the patient was readmitted with symptoms, physical findings, and laboratory evidence consistent with a diagnosis of acute hepatitis. However, results of tests for hepatitis B antigen and antibody were negative as were serologic tests for toxoplasmosis, cytomegalovirus, syphilis, infectious mononucleosis, and antinuclear antibody. All marrow cellular elements were again present in normal numbers. As his clinical condition improved, the platelet count increased from 60,000 to 265,000/mm:'. Liver function tests returned to normal,
Articles in this section should require less than three JOURNALpages: text, less than 1,000 words; 1 or 2 illustrations and/or tables; up to 10 references.
Cerebrospinal fluid glucose measurements with Dextrostix and reflectance meter Duna Penn, M.D.,* Paul R. Williams, M.D., and Robin M. Adair, R o y a l Oak, Mich.
DEXTROSTIX reagent strip determinations Of whole blood glucose by reflectometer have been shown to have excellent correlation with conventional laboratory techniques over various concentrations (10 to 400 mg/dl). 1-~ This method of estimation of blood glucose has gained wide clinical acceptance because it is rapid, accurate, and requires small samples of blood. Attempts to utilize the technique with cerebrospinal fluid, however, have been unsatisfactory. 67 Suggested modifications have proved to be cumbersomes We describe here a convenient modification of the Dextrostix technique that provides a rapid and accurate estimation of glucose concentration in CSF.
METHODS Pooled CSF (from adults and children) was divided into multiple aliquots. Standardized glucose solutions were added to vary the concentrations from 6 to 260 mg/dl. The effect of protein on Dextrostix determinations of glucose was studied by adding varying amounts of Plasmanate to adjust concentrations from 80 to 1,000 mg/ dl. In addition, 54 random CSF samples were analyzed Without manipulation of glucose (3 to 217 mg/dl) or protein concentration (11 to 220 mg/dl). From the Department of Pediatrics, William Beaumont Hospital. *Reprint address William Beaumont Hospital, Royal Oak, MI 48072.
Glucose determinations by Dextrostix (Ames Eyetone Reflectometer) and by glucose analyzer (Beckman Glucose Analyzer) methods were performed on samples in duplicate. Total protein was measured by a turbidimetric procedure using trichloroacetic acid (DuPont Automatic Clinical Analyzer). Dextrostix consists Of an active area impregnated with a glucose oxidase/peroxidase/chromagert system and coated with a semipermeable membrane to prevent access of red blood cells. This membrane might be expected to exhibit different permeabilities to various solutions. The active portion of the Dextrostix was completely covered by CSF. All Dextrostix determinations were performed at room temperature. Aliquots from each sample were tested at 45 seconds (Dextrostix-45) and repeated at 60 seconds (Dextrostix-60). A stopwatch was used for accurate timing. The enzyme strip was washed with distilled water. It was then blotted dry and immediately inserted into the reflectometer. The instrument was left on continuously and calibrated frequently using manufacturer's standards representing 50 and 400 mg/dl glucose concentrations. Abbreviation used CSF: cerebrospinal fluid
[
Results obtained by the Beckman Glucose Analyzer were considered the reference values. Data Were analyzed by the Student's t test, paired t-test, and simple linear regression. RESULTS Fig. 1A demonstrates the close correlation between the Dextrostix-45 measurements and glucose values determined by the reference glucose oxidase method. There were no significant differences between the two methods over the glucose concentration range 10 to 160 mg/dl. Some deviation was noted at higher glucose levels. In Contrast, Fig. 1B demonstrates the correlation between the Dextrostix-60 measurements and the reference values. Despite an excellent correlation coefficient
The Journal of P E D I A T R I C S
771
772
Brief clinical and laboratory' observations
The Journal q[ Pediatrics May 1977
i
240 220. DEXTROSTIX-45't'ILE,M. DEXTRO6TIX-60tS.E.M. - - IDEAL CURVE + +
200"
"[
180.
::]// ----p
0
......
25
I 50
9-~
80~
I.... 75
~
........ ] -
100
125
,ol
" k 150
.iFo
/
~176 [
20
40
60
8~0
' 100
120
OJueose (mg/dl) Beckman Glucose Analyzer
140
160
(r = 0.995), there was significant deviation from the ideal curve. In Fig. 2, all reference glucose determinations were grouped into 10 m g / d l increments. Each locus on the abscissa represents the mean (_+ SEM) on these increments. Loci on the ordinate represent the mean ( • SEM) of Dextrostix determinations corresponding to the reference points included in each 10 m g / d l increments, The close correlation of Dextrostix-45 measurements to the reference method is evident in contrast to the significant deviation of the Dextrostix-60 value from the ideal
y
/.:
50-~
/ /Ny=X
"
0
Fig. 2. Correlation between mean glucose concentrations _+ standard error of the mean obtained by Dextrostix following either 45 or 60 seconds of incubation and the reference glucose oxidase method9 All reference glucose determinations were grouped into 10 mg/dl increments. Each locus on the abscissa represents the mean (_+ SEM) of these increments. Loci on the ordinate represent the mean ( _+ SEM) of Dextrostix determinations corresponding to the reference points included in.each 10 mg/dt increment.
/ '. /
+/
20O l / "
;:0.3,;;-
I
'i' ,/
Fig. IA. Correlation between results obtained by Dextrostix following 45-second incubation and the reference glucose oxidase method; (y = x) represents the ideal curve.
o
§
~ 100
Glucose ( m g / d l ) Beckman Glucose Analyzer
m
L,o
f
: : / ~
curve.
25 II
0
/
"~ " "
25
I
'I 50
I 75
I 100
i 125
I 150
Glucose ( m g / d l ) Beckman Glucose Analyzer Fig. lB. Correlation between results obtained by Dextrostix following 60-second incubation and the reference glucose oxidase method; (y = x) represents the ideal curve
DISCUSSION Rapid and accurate estimation of C S F glucose concentration may be helpful in the investigation of meningitis 9 A blood glucose determination performed at the same time would aid in differentiating between hypoglycemia and meningitis 9 Although blood glucose determinations have been shown to be accurate in other studies?-:' previous attempts to use Dextrostix in the
Volume 90 Number 5
Brief clinical and laboratory observations
routine manner with C S F have generally overestimated glucose v a l u e s . " : Swietek and associates ~ modified the technique to improve the accuracy of CSF determinations with Dextrostix. Unfortunately, their method was time consuming and cumbersome. Accuracy of this modification of the Dextrostix technique is dependent upon several critical factors including: quality control of the Dextrostix reagent sirips; frequent calibration of the reflectometer (at least twice daily); adequate sample size to completely cover the tip of the reagent strip; and strict adherence to the 45-second incubation period. Dextrostix-45 values were consistent with those obtained by the reference glucose oxidase method over a glucose concentration range of 10 to 160 m g / d l and a protein range of 11 to 1,000 m g / d l . These values are well within the scope of those c o m m o n l y encountered in CSF analysis. Therefore, it is suggested that the use of Dextrostix with a 45-second incubation period and the reflectometer may provide a rapid and accurate bedside estimation of C S F glucose.
Coexistent hemophilia A and idiopathic thrombocytopenic purpura Marilyn A. Hruby, M.D., Chicago, Ill.
THE PRESENCE o f unrelated congenital or acquired hematologic disorders in patients with factor VIII deficient hemophilia has previously been reported. These associated conditions have included congenital factor V deficiency,' acute leukemia, ~ an abnormal fibrinogen,:' hereditary hemorrhagic telangiectasia/ a functional abnormality of the platelets,:'." and thrombocytopenia secondary to hypersplenism5 In this report we present the findings of two unusual cases of chronic idiopathic thrombocytopenia occurring in hemophilic patients, with a successful outcome following splenectomy in one case. From the Department of Pediatrics, Northwestern University and Children's Memorial Hospital *Reprint address: Children's Memorial Hospital 2300 Children's Plaza Chicago, 1L 60614.
7 73
REFERENCES
1. Jarrett R J, Keen H, and Hardwick C: "Instant" blood sugar measurement using Dextrostix and a reflectance meter, Diabetes 19:724, 1970. 2. Mazzaferri EL, Skillman TG, Lanese RR, and Keller MP: Use of test strips with colour meter to measure blood glucose, Lancet 1:331, 1970. 3. Scherstein B, Kuhl C, Hollender A, and Ekman R: Blood glucose measurements with Dextrostix and new reflectance meter, Br Med J 3:387, i974. 4. Ente G, Klein SW, and Paraswanath BS: Evaluation of a direct-reading reflectometer for neonatal hypoglycemia screening, Am J Clin Pathol 61:612, 1974. 5. Frantz ID, Medina G, and Taeusch HW: Correlation of Dextrostix values with true glucose in the range less than 50 mg/dl, J PEDIATR87:417, 1975. 6. Marks V, and Dawson A: Rapid stick method for determining blood-glucose concentration, Br Med J 1:293, 1965. 7. Swietek KR, Luebben G, and Cornblath M: Screening method for determining glucose in blood and cerebrospinal fluid, Am J Dis Child 117:672, 1969.
CASE REPORTS Case 1. A 19-year-old Mexican-American boy had a history of easy bruising, hematoma formation, and prolonged bleeding from minor lacerations beginning at two years of age, which led to a diagnosis of mild factor VIII deficient hemophilia (t0% factor VIII). A younger brother was found to be similarly affected. The patient was first noted to be thrombocytopenic in 1964 at the age of seven years when epistaxis appeared and bruising increased in frequency. The platelet count at that time was 27,000/mmL A diagnosis of acute idiopathic thrombocytopenic purpura was made on the basis of history, physical findings, and bone marrow examination. The platelet count returned to normal spontaneously within a few weeks. Over the next three and one-half years the patient was noted to be moderately thrombocytopenic on several occasions. Because of his asymptomatic course, no therapy was instituted. Platelet counts obtained from all family members were within the normal range. In June, 1973, he was admitted to the hospital with findings suggestive of a retroperitoneal hemorrhage. Treatment with daily infusions of cryoprecipitate or factor VIII concentrate resulted in a complete recovery. Two weeks after discharge the patient was readmitted with symptoms, physical findings, and laboratory evidence consistent with a diagnosis of acute hepatitis. However, results of tests for hepatitis B antigen and antibody were negative as were serologic tests for toxoplasmosis, cytomegalovirus, syphilis, infectious mononucleosis, and antinuclear antibody. All marrow cellular elements were again present in normal numbers. As his clinical condition improved, the platelet count increased from 60,000 to 265,000/mm:'. Liver function tests returned to normal,