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Ken Sikaris

Publications and source records attributed to Ken Sikaris.

6 recordsLinked to original sources
PubMed2006

Cardiac troponin levels in asymptomatic patients on the renal transplant waiting list.

AIMS: Cardiac troponin levels predict mortality and cardiovascular events in asymptomatic patients receiving dialysis and may be a useful clinical tool to stratify high-risk asymptomatic individuals. METHODS: The present study examined levels of troponins I (cTnI) and T (cTnT) in patients with chronic renal impairment, patients receiving dialysis and renal transplant recipients. Patients receiving dialysis on the renal transplant waiting list were compared with those excluded from the list based on medical criteria. Median levels were compared using the Kruskal-Wallis test and proportions compared by chi-squared. RESULTS: Median troponin levels were higher in patients on dialysis than transplant recipients. Comparing patients receiving dialysis not listed compared with those listed for renal transplant, median cTnI levels were significantly higher (0.03 versus 0.02 microg/L, P < 0.01) whereas median cTnT levels were not. Patients listed for transplantation were younger, had less clinical cardiovascular disease and lower C-reactive protein than those awaiting renal transplantation. The proportion of patients with elevated cTnT was not substantially different between patients awaiting renal transplantation (38%) and those excluded (52%). Levels of cTnI and cTnT were inversely related to renal function in predialysis and transplant patients, but were not related to time on dialysis for those receiving dialysis therapy. CONCLUSION: As patients awaiting renal transplantation are clinically screened for cardiovascular disease but have frequently elevated cardiac troponin levels, troponin may be a useful clinical tool to identify high-risk asymptomatic patients on dialysis prior to renal transplantation. The influence of renal function on the interpretation of cardiac troponin and risk prediction requires further evaluation.

Adult↗
PubMed2005

Reproductive hormone reference intervals for healthy fertile young men: evaluation of automated platform assays.

CONTEXT: Management of male infertility and/or androgen deficiency requires accurate hormonal measurements with valid reference intervals. OBJECTIVE: The objective of this study was to develop a valid reference panel of blood samples from healthy eugonadal young men with verified normal reproductive function and to use this panel to evaluate the performance of seven fully automated, commercial multiplex immunoassay platforms used to measure serum total testosterone (T), LH, and FSH. DESIGN: This was an observational study of consistency among seven different automated immunoassays for each of total T, LH, and FSH. Each method was implemented in two laboratories, with each repeating the analysis of the full reference panel samples twice. Serum T concentrations were also measured by gas chromatography/mass spectrometry (GC/MS), and serum inhibin B levels were determined by an ELISA. SETTING: The study was performed at commercial, high-volume, clinical pathology laboratories. PARTICIPANTS: From 147 men screened, sera from 124 healthy, reproductively normal men (age, 21-35 yr) with normal sperm output were used as a reference panel. All laboratories selected for elite performance in the national immunoassay quality assurance program agreed to participate. MAIN OUTCOME MEASURE(S): For each of the 868 assays, descriptive statistics were calculated in the natural and log-transformed scales and were analyzed by nested, repeated measures ANOVA after log transformation. Reference intervals, defined as 95% confidence limits, were calculated using arithmetic (natural scale), geometric (log scale) and nonparametric methods. RESULTS: Descriptive statistics and reference intervals for serum T, LH, and FSH differed widely and significantly between methods, but variation between laboratories for the same assay was negligible. All T methods showed significant differences in regression slope and intercept in deviance plots as well as in estimated reference ranges compared with the independent GC/MS reference method. Although similar between-method differences existed for gonadotropin assays, the smaller quantitative discrepancies allowed assignment of consensus reference intervals for serum FSH (1.3-8.4 IU/liter) and LH (1.6-8.0 IU/liter), although these differed from manufacturers' currently quoted expected values. CONCLUSIONS: Using a reference panel of sera from healthy eugonadal young men with verified normal reproductive function, major differences exist between commercial T immunoassays as well as divergence from the GC/MS standard. This impairs their clinical diagnostic utility and requires substantial improvements in automated T immunoassay technologies or a switch to GC/MS methods. Gonadotropin assays showed less variability, but current high-throughput immunoassays remain suboptimal to confirm accurate diagnosis of azoospermia or androgen deficiency.

Adult↗
PubMed2005

Measurement of total testosterone in women: comparison of a direct radioimmunoassay versus radioimmunoassay after organic solvent extraction and celite column partition chromatography.

OBJECTIVE: To evaluate the clinical usefulness for the measurement of testosterone (T) values in the "low" female range with a direct radioimmunoassay (RIA) for total T by comparing total T values measured by this assay with values determined by conventional RIA after organic solvent extraction/column chromatography. DESIGN: Cross-sectional study. SETTING: Victoria, Australia. PATIENT(S): Two hundred fifty-nine healthy women, aged 18-75 years, recruited from the community. INTERVENTION(S): Fasting serum samples were obtained and stored at -80 degrees C. MAIN OUTCOME MEASURE(S): Total T measurement. Total T was measured by the direct RIA method using antibody-coated tubes and iodine-labeled T tracer. For comparison, total T levels were also measured using the conventional RIA method after organic solvent (ethyl acetate:hexane [3:2]) extraction and celite column partition chromatography before RIA. RESULT(S): The mean T level by direct RIA was 0.76 nmol/L (median, 0.70; SD, 0.54; minimum, 0.10; maximum, 3.2). The mean difference between the two measurements (direct RIA - conventional RIA) was -0.28 (SD, 0.3). The direct RIA value was 63% (95% confidence interval, 26%-155%) of the conventional RIA estimate. For the classification of values at the lower end of the range, there was very good agreement beyond chance (kappa = 0.68-0.74) for values in approximately the lowest 10th-40th percentiles. CONCLUSION(S): The direct RIA is a clinically useful assay for the study of the issue of "low" T within the female population.

Adolescent↗
PubMed2005

Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: a position statement.

The systematic staging of chronic kidney disease (CKD) by glomerular filtration measurement and proteinuria has allowed the development of rational and appropriate management plans. One of the barriers to early detection of CKD is the lack of a precise, reliable and consistent measure of kidney function. The most common measure of kidney function is currently serum creatinine concentration. It varies with age, sex, muscle mass and diet, and interlaboratory variation between measurements is as high as 20%. The reference interval for serum creatinine concentration includes up to 25% of people (particularly thin, elderly women) who have an estimated glomerular filtration rate (eGFR) that is significantly reduced (< 60 mL/min/1.73 m). The recent publication of a validated formula (MDRD) to estimate GFR from age, sex, race and serum creatinine concentration, without any requirement for measures of body mass, allows pathology laboratories to "automatically" generate eGFR from data already acquired. Automatic laboratory reporting of eGFR calculated from serum creatinine measurements would help to identify asymptomatic kidney dysfunction at an earlier stage. eGFR correlates well with complications of CKD and an increased risk of adverse outcomes such as cardiovascular morbidity and mortality. We recommend that pathology laboratories automatically report eGFR each time a serum creatinine test is ordered in adults. As the accuracy of eGFR is suboptimal in patients with normal or near-normal renal function, we recommend that calculated eGFRs above 60 mL/min/1.73 m be reported by laboratories as "> 60 mL/min/1.73 m", rather than as a precise figure.

Journal Article↗
PubMed2004

BNP--Considering a heartfelt message.

The natriuretic hormones have been discovered as mediators of the cardiac response to volume overload and mechanical dysfunction. Although there are some physiological differences between atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), it is BNP that has been found to be most useful as a clinical test. BNP is secreted along with an N terminal proBNP cleavage product (NT-proBNP). The similarities between these two tests are far greater than the differences. They are both probably useful in the diagnosis of high-risk patients (e.g. dyspnoeic) and may be useful in monitoring cardiac failure treatment. Although BNP levels in the normal range predict the risk of cardiac events and mortality, there is little evidence to promote their use as a screening test. In such an important condition as cardiac failure we should consider any messages that are likely to be of value, particularly those that are heartfelt.

Journal Article↗