Jocelyn M. Hicks

Method for the automatic determination of serum iron

A simple method is described for the automated determination of serum iron and tota iron-binding capacity, which eliminates the need to render apparatus or reagents iron-free. The method is faster than normal procedures and its accuracy is comparable with other accepted methods for the determination of serum iron.

Cerebrospinal fluid lactic acid levels in meningitis

Measurement of cerebrospinal fluid lactic acid by gas liquid chromatography and by an enzymatic Monotest lactate test was evaluated for the early detection of bacterial meningitis in 396 patients. Spinal fluid specimens from 62/62 patients with a bacterial or mycoplasma etiology yielded lactate levels greater than the upper limits of normal, whereas specimens from 334 patients with no bacterial involvement gave values within the normal range. The duration of elevated CSF lactate values coincided with the clinical response to therapy. When considered along with the history and physical examination of the patient, determination of lactic acid proved to be a rapid and reliable diagnostic test for the early detection of untreated as well as partially treated pyogenic meningitis.

Abnormal blood constituents in acute renal failure

Abstract Three patients with acute renal failure and one patient with normal renal function were dialysed on the artificial kidney. The dialysates were examined for the presence of phenolic acids. Many phenolic acids were identified which are normal constituents of urine together with several phenolic acids of the 2-hydroxy series which are not normally present in urine. Although the patients were on a protein-free regime, several compounds were found which had previously been believed to be of dietary origin. The probable metabolic pathways involved are discussed.

Recommendations and opinions for the use of point-of-care testing for hospitals and primary care: summary of a 1999 symposium.

As part of a symposium on laboratory medicine, a colloquium on point-of-care testing was held in June 1999 where four experts were invited to produce recommendations and opinions on the use of point-of-care testing under various clinical venues. Each commented on costs for providing POCT services. A total of eleven recommendations and four opinions were rendered and discussed in an open forum. While one expert concluded that some forms of POCT are less expensive than central laboratory testing if entire laboratory workstations are eliminated, another expert suggested that POCT offered little advantage if rapid transport systems are available. A recommendation was made that POCT be considered for analytes that have a required reporting turnaround time of <30 min, and that the goals for precision and accuracy should be dictated by the clinical need and not by analytical limitations. Recommendations for POCT in specific clinical situations include use of glycated hemoglobin and urine albumin testing with personal glucose monitoring at the time of consultation, use of glycated albumin for gestational diabetes, leukocyte esterase and nitrite testing in urine to screen for urinary tract infections, coagulation tests for monitoring patients on oral anticoagulant therapy and in the operating room, testing for H. pylori for patients with dyspepsia, and cardiac markers and urine drugs-of-abuse testing in the emergency department.

Evaluation of the technicon immuno I® random access immunoassay analyzer and calculation of pediatric reference ranges for endocrine tests, T-uptake, and ferritin

OBJECTIVES Evaluation of the precision, accuracy, and user-friendliness of the Technician Immuno I. Calculation of pediatric reference ranges for ferritin and endocrine tests run on Immuno I. METHODS Precision and accuracy were measured using controls and method comparison studies. Pediatric reference ranges were calculated by comparing the Immuno I results for 100 patients with those of the Abbott IMx and TDx. The regression equation obtained was then used to convert the IMx and TDx reference ranges to reference ranges for the Immuno I. RESULTS The Immuno I provided both accurate and precise measurement of drugs and endocrine hormones. Pediatric reference ranges were obtained for ferritin and all endocrine tests. CONCLUSION The Immuno I is user-friendly and provides reliable measurement of both the drugs tested and endocrine tests on a micro-sample. Reagent and curve stability are excellent.

Falsely increased digoxin concentrations in samples from neonates and infants

Several previous studies have suggested the presence of a digoxin-like immunoreactive substance in the serum of infants. In this study we examined eight different immunoassay kits to confirm the presence of such a substance. The kits were evaluated using serum from newborns and infants who were not receiving digoxin. We investigated the relationship of this digoxin-like immunoreactive substance to substances that are present in unusual concentrations in newborn sera. These substances included fatty acids, cholesterol, triglycerides, bilirubin, protein, and albumin. No relationship could be established. Since serum steroid concentrations are known to be increased in the newborn and since digoxin is essentially a steroid derivative, we looked at steroids separately and collectively to see whether they mimicked the immunoreactivity of digoxin. We found that pooled steroids did indeed mimic digoxin and might be implicated as the immunoreactive substances.

Monitoring pediatric serum theophylline, phenobarbital, and phenytoin with the IL Multistat III.

Summary We compared results of theophylline, phenobarbital, and phenytoin assays by the EMIT® method using the IL Multistat III® Micro Centrifugal Analyzer with results by the EMIT semiautomated procedure on a Beckman 25 spectrophotometer equipped with a semiautomated pipettor-dilutor and a model 2400 automatic timer/printer. We assessed linearity, precision, specificity, and correlation with other methods. The IL MCA III is precise, easy to use, and suitable for routine use in a pediatric laboratory. Only 3 μl of serum is used for each drug analysis, and 17 results can be obtained in 8 min. Reagent costs can be reduced fourfold.

Cerebrospinal Fluid Lactate Determination: A New Parameter for the Diagnosis of Acute and Partially Treated Meningitis

The lactic acid level in the cerebrospinal fluid of 250 patients with or without bacterial involvement was determined using Gas Liquid Chromatography (GLC). This recently rediscovered technique proved effective and reliable in distinguishing between bacterial (21 cases) and non bacterial (179 cases) meningitis. There were no false positives nor false negatives in either category. Partially treated meningitis had elevated CSF lactate on admission. The duration of elevated CSF lactate correlated with the clinical response to therapy. This simple and rapid technique warrants further evaluation as a parameter to detect bacterial central nervous system invasion.

Adaptation of the EMIT gentamicin and tobramycin procedure to the IL microcentrifugal analyzer.

We have adapted the Syva Emit® gentamicin and tobramycin procedure to the IL microcentrifugal analyzer, MCA III®. With this instrument the recommended instructions for reagent preparation and reaction sequence did not produce a useable standard curve. We modified the dilutions and volumes for the working reagents and reversed the sequence of addition of the working reagents. We assessed the linearity and precision of the analysis and compared the Syva gentamicin and tobramycin Emit procedure on the IL MCA III with the semiautomated procedure on a Gilford Stasar III spectrophotometer. With the IL MCA III® only 3 to 5μ of serum is used, 17 analyses can be obtained in 8 min, and the reagent costs are reduced considerably.

Adolescent pregnancy testing: Which test to use

In order to study the sensitivity and efficiency of five pregnancy tests, we evaluated four types of urine tests in 162 adolescent girls in whom pregnancy was suspected; a serum test was performed in 46 of them. We found that (1) an increase in sensitivity occurred at the expense of specificity, (2) the quantitation of the beta-subunit of human chorionic gonadotropin in serum proved to be the most reliable test for pregnancy, and (3) the latex agglutination inhibition tube test (Placentex) was the most accurate of the four types of urine tests evaluated. We concluded that for adolescents, the serum pregnancy test is the preferred test, but when it is not available, the urine latex agglutination inhibition tube test offers the most reliable alternative.