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Laboratory Test Results. Brenda C. Barnes and Shawn Froelich. Urinalysis. Physical Examination of Urine. Chemical Examination. Chemical Exam – Glucose . Presence of glucose indicates the amount blood glucose has exceeded tubular reabsorptive capacity Clinical correlation
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Laboratory Test Results Brenda C. Barnes and Shawn Froelich
Chemical Exam – Glucose • Presence of glucose indicates the amount blood glucose has exceeded tubular reabsorptive capacity • Clinical correlation • Diabetes mellitus • Pancreatitis • Hyperthroidism • Gestational diabetes
Glucose • Clinitest • Nonspecific test for reducing substances • If performed, done so on pediatric specimens (< 2 years old) • Screening for galactosemia – may be part of state mandated newborn screening program • Microscopic Correlation • No elements seen • Yeast may be present
Chemical Exam – Bilirubin • Presence indicates liver disease or biliary obstruction • False-positives due to urine pigments • Ictotest – confirmatory test • Less subject to interference • False-negatives • Age of specimen – bilirubin is unstable • No microscopic correlation
Chemical Exam – Ketones • Presence indicates increased fat metabolism • Clinical significance • Diabetic acidosis • Insulin dosage monitoring • Starvation • Malabsorption • Microscopic correlation - none
Chemical Exam – Sp. Gravity • Strip reading is adequate for routine screening • Clinical significance • Monitoring patient hydration and dehydration • Loss of renal tubular concentrating ability • Diabetes insipidus • Determination of unsatisfactory specimens • Microscopic correlation – none
Chemical Exam – Blood • Presence of red blood cells, hemoglobin, or myoglobin • Hematuria - bleeding • Hemoglobinuria • Lysis of rbc in specimen • Intravascular hemolysis • Myoglobinuria – muscle destruction • Microscopic correlation – rbc seen in hematuria
Chemical Exam – pH • Of little diagnostic value – primarily used for determining systemic acid-base disorders • Microscopic correlation – none
Chemical Exam – Protein • Presence indicates abnormality in glomerular filtration barrier – renal disease • Correlates with: • Nitrite • Leukocytes • Microscopic
Chemical Exam - Urobilinogen • Increased in any condition that causes an increase in production or retention of bilirubin • Clinical significance • Early detection of liver disease • Lever disorders, hepatitis, cirrhosis, carcinoma • Hemolytic disorders • Microscopic correlation – none
Chemical Exam – Nitrite • Rapid screening for UTI • Sample needs to be fresh to avoid false-positive reactions • Correlates with: • Protein • Leukocytes • Microscopic
Chemical Exam – Leukocytes • Screening test for presence of wbc in urine • Quantification should be done by microscopic examination • Correlates with: • Protein • Nitrite • Microscopic
Microscopic Examination • Detect and identify insoluble materials present in urine • Time-consuming = cost • Lacks standardization Protocols used by many labs to improve standardization and cost-effectiveness
Anaerobic Specimens • Most anaerobic infections are caused by endogenous microbiota • Improper collection may result in the growth of many anaerobes, resulting in difficulty to determine the cause of infection • Labs follow criteria for rejection of inappropriately collected and/or transported specimens
Acceptable Specimens for Anaerobic Culture • Aspirated material • CSF, blood, bone marrow, synovial fluid • Aspiration of closed abscess, ascites fluid, peritoneal fluid • Deep tissue or bone biopsy • Aspirated pus from decubitus ulcers • Suprapubic bladder aspiration • Pleural fluid obtained by thoracentesis, open lung biopsy, “sulfur granules” from draining fistula
Unacceptable Specimens for Anaerobic Culture • Swabs • Throat, nasopharyngeal, gingival, rectal, vaginal, cervical, urethral, surface wounds and abscesses • Expectorated or suctioned sputum, bronchial washings • Contents of large bowel, feces, colostomy effluents, gastric and small bowel contents • Voided or catheterized urine
Transport and Processing of Anaerobic Specimens • Transport and processing should be quick to maintain temperature, avoid exposure to oxygen and avoid dessication • Oxygen-free transport tubes/vials such as PRAS media (prereduced, anaerobically sterilized) • Anaerobic bags or pouches if delays in transport • Blood cultures require aseptic collection with bactericidal agent such as tincture of iodine or chlorhexidinegluconate with 70% alcohol to minimize contamination with normal skin biota