Dogan Yucel

Can routine automated urinalysis reduce culture requests

OBJECTIVES There are a substantial number of unnecessary urine culture requests. We aimed to investigate whether urine dipstick and microscopy results could accurately rule out urinary tract infection (UTI) without urine culture. DESIGN AND METHODS The study included a total of 32,998 patients (11,928 men and 21,070 women, mean age: 39 ± 32 years) with a preliminary diagnosis of UTI and both urinalysis and urinary culture were requested. All urine cultures were retrospectively reviewed; association of culture positivity with a positive urinalysis result for leukocyte esterase (LE) and nitrite in chemical analysis and pyuria (WBC) and bacteriuria in microscopy was determined. Diagnostic performance of urinalysis parameters for detection of UTI was evaluated. RESULTS In total, 758 (2.3%) patients were positive by urine culture. Out of these culture positive samples, ratios of positive dipstick results for LE and nitrite were 71.0% (n=538) and 17.7% (n=134), respectively. The positive microscopy results for WBC and bacteria were 68.2% (n=517) and 78.8% (n=597), respectively. Negative predictive values for LE, nitrite, bacteriuria and WBC were very close to 100%. CONCLUSIONS Most of the samples have no or insignificant bacterial growth. Urine dipstick and microscopy can accurately rule out UTI. Automated urinalysis is a practicable and faster screening test which may prevent unnecessary culture requests for majority of patients.

Urinary 8-hydroxy-2′-deoxyguanosine level and plasma paraoxonase 1 activity with Alzheimer’s disease

Abstract Background: Alzheimer’s disease (AD) is the most frequent cause of dementia and age is the most important risk factor for AD. Aging is associated with increased free radical production and oxidative stress plays an important role in the pathogenesis of AD. 8-Hydroxy-2′-deoxyguanosine (8-OHdG) is a biomarker indicating oxidative DNA damage. Paraoxonase 1 (PON1) is a high-density lipoprotein (HDL)-associated antioxidant enzyme and prevents especially oxidation of low-density lipoproteins. The aim of this study is to measure urinary 8-OHdG levels and serum PON1 activity in patients with AD. Methods: A total of 21 elderly patients diagnosed with moderate AD (10 men and 11 women, aged 76±7.8 years) were included in the study. A total of 20 healthy elderly volunteers (11 men and nine women, aged 81±7.2 years) were enrolled as a control group. Levels of urinary 8-OHdG, serum PON1 activity and lipid profile were determined in patients and controls. Results: Urinary 8-OHdG levels were significantly increased, but serum PON1 activity was significantly decreased in patients compared to controls. Lipid profile did not show a difference between the groups. There was a negative correlation between 8-OHdG levels and PON1 activity only in the patient group (r=–0.536). Analytical performance characteristics of the methods used were satisfactory. Conclusions: In this study, evidence of increased oxidative DNA damage was determined in AD patients as well as decreased serum PON1 activity. Oxidant stress and oxidative DNA damage are important pathological processes in AD. The biomarkers, urinary 8-OHdG level and serum PON1 activity can be used to determine and monitor the status of patients with AD.

Effect of albumin concentration and serum matrix on ischemia-modified albumin

OBJECTIVES There is concern that ischemia-modified albumin (IMA) levels measured by albumin cobalt binding (ACB) assay reflect mainly albumin concentrations rather than myocardial ischemia. DESIGN AND METHODS Serum matrix and proteins were separated from a serum pool by a membrane filter. Two series of pools with albumin concentrations of 10, 20, 30, 40, 50, and 60 g/L were prepared either with human albumin or serum protein fraction. IMA values of these pools were measured in quintiplicate. RESULTS There was a strong negative correlation between IMA and albumin levels in both pools. IMA change corresponding to each 10 g/L difference in albumin concentration was 37% and 48% in these pools. CONCLUSIONS ACB assay reflects albumin concentrations rather than IMA. Primary predictor of IMA in serum matrix is albumin concentration.

Are preservatives necessary in 24-hour urine measurements?

BACKGROUND 24-h urine measurements are used in the routine diagnosis and follow-up of many diseases in the clinical laboratory. Calcium (Ca(2+)), magnesium (Mg(2+)), phosphate (PO(4)(3-)) and uric acid are frequently requested markers in 24-h urine samples. Because of the different solubilities of these parameters, different urine collection conditions - urine in base for uric acid and urine in acid for Ca(2+), PO(4)(3-) and Mg(2+) measurements - are recommended. METHODS We aimed to test the effect of addition of preservatives and heating of the urine specimen on the results obtained for Ca(2+), Mg(2+), PO(4)(3-) and uric acid by comparison with untreated samples results. Spot (n=20) and 24-h urine (n=50) samples were obtained from patients for routine urine analysis. A single spot urine sample was divided into five aliquots of 10 mL each: one containing 200 microL of HCl (6 N), another containing 200 microL of sodium bicarbonate, NaHCO(3) (5 g/L), two others in which the same preservative agents were added 24 h after the collection, and one without any preservative (untreated). Ca(2+), PO(4)(3-), uric acid and Mg(2+) were measured in triplicate and at three different time points during the study: at the time of sampling (0 h), 24 h after sampling, and after heating the samples. The 24-h urine samples were collected without preservatives and analytes were measured promptly before and after acidification/alkalinization. RESULTS There was no statistically significant difference between untreated and treated samples (p>0.05). Heating also failed to show any difference in the results (p>0.05). CONCLUSION According to our results, addition of preservatives is not necessary for measurement of Ca(2+), Mg(2+), PO(4)(3-) and uric acid in promptly assayed 24-h urine samples.

Coenzyme Q10 and high-sensitivity C-reactive protein in ischemic and idiopathic dilated cardiomyopathy.

Abstract Background: Cardiomyopathy (CMP) is a common debilitating illness, associated with a high mortality and poor quality of life. There is extensive evidence from in vitro and animal experiments that CMP is a state of increased oxidative stress. Coenzyme Q10 (CoQ10) and high-sensitivity C-reactive protein (hs-CRP) are important markers to evaluate the oxidative stress and inflammatory status of patients with CMP. Methods: A total of 28 patients with chronic stable heart failure (21 men and 7 women, ages 18–76 years) were included in the study. Causes of heart failure were ischemic CMP in 17 patients and idiopathic dilated CMP in 11 patients. A total of 28 patients (12 men and 16 women; ages 30–71 years) with normal coronary angiography were enrolled as a control group. Levels of CoQ10, albumin, total thiol groups (T-SH), bilirubin, uric acid as plasma antioxidants, hs-CRP as an inflammation marker and lipid profile were studied in patients and controls. Results: Plasma CoQ10, T-SH and albumin levels were significantly decreased in patients compared to controls. Uric acid, bilirubin and hs-CRP levels were found to be significantly increased compared to controls. Conclusions: In this study, evidence of decreased antioxidant status was determined in CMP patients together with vascular inflammation. CoQ10, other plasma antioxidants and hs-CRP measured routinely can reflect decreased antioxidant status and inflammatory process in patients with dilated CMP. These markers can be used to monitor the status of patients with CMP. Clin Chem Lab Med 2008;46:382–6.

Relationship between high sensitivity troponins and estimated glomerular filtration rate.

BACKGROUND Diagnosis of acute coronary syndrome may be challenging because of high troponin concentrations in patients with chronic kidney disease. OBJECTIVE the aim of this study is to investigate the difference between high sensitivity troponin T and troponin I in four groups of patients separated according to eGFR values and the effect of renal function both on troponin T and troponin I. METHODS 119 outpatients were divided into 4 groups according to their eGFR values as Group 1: eGFR<30, Group 2: eGFR between 30 and 60, Group 3: eGFR between 60 and 90 and Group 4: eGFR >90mL/min/1.73m(2). The cardiac troponin T and I concentrations were measured concurrently. RESULTS Troponin T values of all patients who have eGFR values lower than 30mL/min/1.73m(2) were above the decision point, but cTnI values of only 2 patients were above the decision limit (40ng/L) in this group. There was a strong and significant negative relationship between eGFR and hs-cTnT [log(y)=2.3-0.72log(x); R(2)=0.625] whereas there was no significant relationship between eGFR and hs-cTnI [log(y)=1.28-0.08log(x); R(2)=0.013] when eGFR was taken into consideration as a continuous variable. CONCLUSION In this study, we found that cTnT increases with decreasing eGFR values, but cTnI is not affected by the change in eGFR values.

What should be the laboratory approach against isolated prolongation of a activated partial thromboplastin time

This study is a retrospective evaluation of patients who were subject to mixing study in our laboratory due to prolonged APTT. The preliminary diagnoses, clinical manifestations, and results of additional ordered tests were reviewed. The study aims to investigate whether repeating APTT test with a different assay prior to performing mixed study in patients with prolonged APTT would be a better alternative algorithmic approach in order to save both time and costs.

Total-and lipid-associated sialic acid in serum and thrombocytes in patients with chronic heart failure.

OBJECTIVES To investigate and discuss the total-, lipid-associated, and thrombocyte-sialic acid levels in chronic heart failure (CHF) patients. DESIGN AND METHODS Thirty-one chronic heart failure patients and 38 healthy controls were included in the study. Serum total sialic acid (TSA), lipid associated sialic acid (LASA), thrombocyte sialic acid (TrSA) were determined together with the traditional inflammation and prognostic markers. RESULTS Serum TSA levels were significantly higher in patient group (3.08 + or - 0.33 mmol/L) than control group (2.60 + or - 0.17 mmol/L). Serum LASA, homocysteine, high-sensitivity CRP, brain natriuretic peptide and erythrocyte sedimentation rate were also significantly higher in patient group. TrSA levels were not significant between the groups. CONCLUSION TSA and LASA levels increase in CHF, independent from coronary artery disease. TrSA levels were not found to be a prognostic or valuable marker for CHF patients. Acute phase response and lipid associated portions of SA are thought to be responsible for SA rise in CHF.

Tumor marker requests in a general teaching Turkish hospital

Serum tumor markers may be requested inappropriately by clinicians. In this retrospective study, we aimed to investigate the appropriateness of TM requests in our hospital. Patients in the study were identified from the TM requests for 3 months between June–August 2004, using the laboratory database. A total of 2249 patients (1351 men, 898 women) were included in the study and there were 6570 TM requests. The number of requests were 1050 (16%) for Carbohydrate Antigen 19-9, 993 (15.1%) for Cancer Antigen 125, 941 (14.3%) for Prostate Specific Antigen, 921 (14%) for free PSA, 925 (14.1%) for Cancer Antigen 15-3, 788 (12%) for Alphafetoprotein, 730 (11.1%) for Carcinoembryonic Antigen and 222 (3.4%) for AFP/Human Chorionic Gonadotrophin. Our findings support the idea that for the evidence-based use of TM requests the education of clinical staff is required. Clear clinical guidelines including recommendations about the appropriate use of TM can be useful for this education process. Careful audit studies are also useful to determine the impact of these guidelines on the practice of evidence-based laboratory medicine.

Falsely Elevated Glucose Concentrations in Peritoneal Dialysis Patients Using Icodextrin

Peritoneal dialysis (PD) is used as an alternative to hemodialysis in end‐stage renal disease (ESRD). Icodextrin has been used as a hyperosmotic agent in PD. The aim of the study was to assess two different point‐of‐care testing (POCT) glucose strips, affected and not affected by icodextrin, with serum glucose concentrations of the patients using and not using icodextrin.