David W. Seccombe

Bio: David W. Seccombe is an academic researcher from University of British Columbia. The author has contributed to research in topics: Carnitine & Digoxin. The author has an hindex of 20, co-authored 48 publications receiving 1526 citations. Previous affiliations of David W. Seccombe include Vancouver General Hospital.

Current Issues in Measurement and Reporting of Urinary Albumin Excretion

Abstract: Background: Urinary excretion of albumin indicates kidney damage and is recognized as a risk factor for progression of kidney disease and cardiovascular disease. The role of urinary albumin measurements has focused attention on the clinical need for accurate and clearly reported results. The National Kidney Disease Education Program and the IFCC convened a conference to assess the current state of preanalytical, analytical, and postanalytical issues affecting urine albumin measurements and to identify areas needing improvement. Content: The chemistry of albumin in urine is incompletely understood. Current guidelines recommend the use of the albumin/creatinine ratio (ACR) as a surrogate for the error-prone collection of timed urine samples. Although ACR results are affected by patient preparation and time of day of sample collection, neither is standardized. Considerable intermethod differences have been reported for both albumin and creatinine measurement, but trueness is unknown because there are no reference measurement procedures for albumin and no reference materials for either analyte in urine. The recommended reference intervals for the ACR do not take into account the large intergroup differences in creatinine excretion (e.g., related to differences in age, sex, and ethnicity) nor the continuous increase in risk related to albumin excretion. Discussion: Clinical needs have been identified for standardization of ( a ) urine collection methods, ( b ) urine albumin and creatinine measurements based on a complete reference system, ( c ) reporting of test results, and ( d ) reference intervals for the ACR.

Establishing reference intervals for clinical laboratory test results: is there a better way?

Abstract: Reference intervals are essential for clinical laboratory test interpretation and patient care. Methods for estimating them are expensive, difficult to perform, often inaccurate, and nonreproducible. A computerized indirect Hoffmann method was studied for accuracy and reproducibility. The study used data collected retrospectively for 5 analytes without exclusions and filtering from a nationwide chain of clinical reference laboratories in the United States. The accuracy was assessed by the comparability of reference intervals as calculated by the new method with published peer-reviewed studies, and reproducibility was assessed by the comparability of 2 sets of reference intervals derived from 2 different data sets. There was no statistically significant difference between the calculated and published reference intervals or between the 2 sets of intervals that were derived from different data sets. A computerized Hoffmann method for indirect estimation of reference intervals using stored test results is proved to be accurate and reproducible.

Effect of fasting on free and esterified carnitine levels in human serum and urine: Correlation with serum levels of free fatty acids and β-hydroxybutyrate

Abstract: Serum levels of free L-carnitine, acylcarnitines, creatinine, beta-hydroxybutyrate, free fatty acids, cholesterol, triglycerides, and glucose were determined in healthy volunteers during a 24-36-hr fast. The effect of oral administration of free L-carnitine (1 g/person) on these parameters was studied. Urinary excretion of carnitine and creatinine was monitored throughout. Serum and urine levels of free carnitine and its renal clearance decreased during the fast. However, the serum concentration and urinary excretion of acylcarnitines increased during the same interval. Following the ingestion of free L-carnitine, both serum and urinary levels of free L-carnitine rose. Within 6 hr of ingestion, 10% of the administered dose could be accounted for by urinary excretion. No significant effect on the other serum constituents under study was seen following the oral L-carnitine dose. A significant negative correlation was found between serum levels of free L-carnitine and beta-hydroxybutyrate and free fatty acids (r equal -0.567, p less than 0.001 and r equal -0.607, p less than 0.001, respectively) during the fast.

Plasma carnitine levels during intravenous feeding of the neonate.

Abstract: The premature infant has a limited capacity for fatty acid oxidation This study shows that solutions commonly used for intravenous feedings in the newborn infant contain no carnitine Infants maintained on this solution have significantly lower total, free, and acylcarnitine levels as compared to when they are fed orally with expressed human milk or a proprietary formula, which is known to contain carnitine The exogenous supply of carnitine to the premature infant may have a significant influence on the ability to stimulate optimal fatty acid oxidation

International expert committee report on the role of the A1C assay in the diagnosis of diabetes

Abstract: We appreciate the comment by Kilpatrick et al. (1) regarding the International Expert Committee report on the diagnosis of diabetes with the A1C assay (2). The Committee considered all of the limitations of the A1C assay for populations in which it is not available or is currently too expensive, as well as for individuals in whom the assay may be misleading. On the basis of these recognized limitations, the Committee emphasized the use of the currently recommended glucose tests and criteria in such populations or individuals. We did not “breeze over” any of the relative advantages or disadvantages of the A1C assay as a means of diagnosis; rather, the …

Carnitine--metabolism and functions

Abstract: Carnitine was detected at the beginning of this century, but it was nearly forgotten among biochemists until its importance in fatty acid metabolism was established 50 years later. In the last 30 years, interest in the metabolism and functions of carnitine has steadily increased. Carnitine is synthesized in most eucaryotic organisms, although a few insects (and most likely some newborn animals) require it as a nutritional factor (vitamin BT). Carnitine biosynthesis is initiated by methylation of lysine. The trimethyllysine formed is subsequently converted to butyrobetaine in all tissues; the butyrobetaine is finally hydroxylated to carnitine in the liver and, in some animals, in the kidneys (see Fig. 1). It is released from these tissues and is then actively taken up by all other tissues. The turnover of carnitine in the body is slow, and the regulation of its synthesis is still incompletely understood. Microorganisms (e.g., in the intestine) can metabolize carnitine to trimethylamine, dehydrocarnitine (b...

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

Abstract: Background: Multiple laboratory tests are used in the diagnosis and management of patients with diabetes mellitus The quality of the scientific evidence supporting the use of these assays varies substantially Approach: An expert committee drafted evidence-based recommendations for the use of laboratory analysis in patients with diabetes An external panel of experts reviewed a draft of the guidelines, which were modified in response to the reviewers’ suggestions A revised draft was posted on the Internet and was presented at the AACC Annual Meeting in July, 2000 The recommendations were modified again in response to oral and written comments The guidelines were reviewed by the Professional Practice Committee of the American Diabetes Association Content: Measurement of plasma glucose remains the sole diagnostic criterion for diabetes Monitoring of glycemic control is performed by the patients, who measure their own plasma or blood glucose with meters, and by laboratory analysis of glycated hemoglobin The potential roles of noninvasive glucose monitoring, genetic testing, autoantibodies, microalbumin, proinsulin, C-peptide, and other analytes are addressed Summary: The guidelines provide specific recommendations based on published data or derived from expert consensus Several analytes are of minimal clinical value at the present time, and measurement of them is not recommended