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chem exam of urine
| Question | Answer |
|---|---|
| longest test | leukocyte esterase - 2 minutes |
| store strips at | below 30*C |
| how often should QC be ran? | at least per 24 hrs or once per shift |
| why cant distilled H2O be used as a negative control? | rx are designed for urine ionic concentration |
| sensitivity | least amount of a substance that can give a positive |
| specificity | reaction that occur only with a certain substance |
| false positives decrease the ___________ of the test false negatives decreases the ________________ of the test | specificity sensitivity |
| first morning specimens pH is usually | more acidic: 5-6 |
| postprandial specimen pH is usually more | alkaline |
| normal range for pH | 4.5 - 8 |
| pH of 9+ indicates | an old bacterial contaminated specimen |
| meat causes urine pH to be more _____________, while vegetables cause it to be more ______________ | acidic; alkaline |
| clinical significance of urine pH | respiratory/metabolic acidosis/alkalosis, tubular secretion and reabsorption defects, renal calculi formation, UTI, crystal identification, |
| indicators for pH | 4-6: methyl red --> red/orange to yellow 6-9: bromothymol blue --> green to blue |
| protein is indicative of | renal disease |
| normal for urine protein | <10 mg/dL or 100 mg/day |
| primary protein of concern | albumin |
| clinical proteinuria values | >30 mg/dL or 300mg/day |
| prerenal proteinuria | conditions affecting the plasmas- not the kidneys |
| Bence Jones Protein is seen in | multiple myeloma |
| prerenal tubular disorders | intravascular hemolysis, muscle injury, acute phase reactants, multiple myeloma |
| glomerular proteinuria | damage to glomerular membrane; impaired selective filtration causes increased protein filtration --> abnormal substances deposit on the membrane |
| what can cause glomerular proteinuria? | lupus, streptococcal glomerularnephritis |
| orthostatic (postural) proteinuria | occurs in vertical position, disappears in horizontal position |
| orthostatic proteinuria reagent strips results | negative |
| tubular proteinuria | tubular damage affecting reabsorptive activity |
| postrenal proteinuria | protein added in the lower urinary and genitourinary tract |
| indicator for protein | tetrabromophenol blue |
| trace values are | <30mg/dL |
| reaction interference for protein | highly pigmented urine, quaternary ammonium compounds, detergents, antiseptics, chlorhexidine |
| sulfosalicylic acid (SSA) is confirmation for | protein |
| exton's reagent | NaSO4 |
| extons reagent is used for which test | SSA |
| micral test | gold labeled anti-human antibody enzyme conjugate |
| what color is positive for the micral test | various shades of red - different degrees |
| darker bottom band for immunodip | unbound ab <1.2 mg/dL |
| equal band colors for the immunodip | 1.2-1.8 mg/dL |
| darker top band for immunodip | bound ab 2-8 mg/dL |
| non-diabetic causes of glycosuria | pancreatitis, pancreatic cancer, acromegaly, Cushings syndrome, hyperthyroidism, pheochromocytoma |
| hyperglycemia associated clinical significance of urine glucose | diabetes mellitus, pancreatitis, pancreatic cancer, acromegaly, cushings, hyperthyroidism, CNS damage, gestational diabetes |
| renal associated clinical significance of urine glucose | fanconi syndrome, advanced renal disease, osteomalacia, pregnancy |
| reaction interference for glucose | peroxide, oxidizing detergents --> false positives ascorbic acid, ketones, high SG, old specimens --> false negatives |
| clinitest tablets | copper sulfate, sodium carbonate, sodium citrate, sodium hydroxide |
| sodium citrate + NaOH = | heat |
| sensitivity of the clinitest | 200 mg/dL |
| clinitest is also used for | galactosemia testing in newborns |
| ketones: | acetone (2%) acetoacetic acid (20%) beta-hydroxybutyric acid (78%) |
| primary causes of ketonuria | diabetes mellitus, vomiting, starvation, malabsorption |
| reagent strips for ketones primarily measure | acetoacetic acid |
| primary reagent for ketones | sodium nitroprusside |
| acetoacetic acid + nitroprusside --> | purple |
| acetest | confirmatory test for ketones |
| medications with sulfhydryl groups can interfere with what test | ketones |
| is the reagent strip or microscopic examination more accurate for blood | reagent strip |
| hematuria | intact RBCs, cloudy red urine |
| hematuria is caused by | renal calculi, glomerulonephritis, pyelonephritis, tumors, trauma, toxic chemical exposure, anticoagulants, strenuous exercise |
| hemoglobinuria | clear red urine |
| hemoglobinuria causes | transfusion rx, hemolytic anemias, severe burns, infections/malaria, strenuous exercise, brown recluse spider bites |
| hemosiderin | yellow brown granules in sediment |
| myoglobinuria | heme containing protein in muscle tissue; clear, red brown urine |
| myoglobin + NH4SO4 --> | red supernatant |
| hemoglobin + NH4SO4 --> | clear supernatant |
| intact RBCs show a | speckled pattern |
| sensitivity of blood reagent strip | 5 RBCs /uL |
| false positives for blood can be caused by | strong oxidizing agents, bacterial peroxidases, menstrual contamination |
| false negatives for blood can be caused by | high SG/ crenated cells |
| urine bilirubin is an early indicator of | liver disease |
| conjugated bilirubin appears in urine with | bile duct obstruction and liver disease |
| hemolytic disease increases | unconjugated bilirubin |
| bilirubin testing utilizes what kind of reaction | diazo |
| confirmatory test for bilirubin | ictotest |
| ictotest sensitivity | 0.05-0.10 mg/dL |
| false positives in bilirubin is caused by | urine pigments, pyridium, indican, Lodine |
| false negatives for bilirubin caused by | old specimens, ascorbic acid and nitrite |
| how do ascorbic acid and nitrite interfere with bilirubin testing | they bind diazonium salt, blocking bilirubin rx |
| what is there always a little bit of in urine? | urobilinogen |
| urobilinogen is significant in | early detection of liver disease |
| hemolytic disorders see ________________ bilirubin and ___________________ urobilinogen | negative bilirubin; strong positive urobilinogen |
| urobilinogen results with bile duct obstruction | normal |
| multistix reagent | p-dimethylaminobenzaldehyde (Ehrlich reagent) |
| urobilinogen is normally | 0.2-1 |
| chemstrip reagent | 4-methoxybenzen-diazonium-tetrafluoroborate |
| urobilinogen is highest | after meals |
| Ehrlich tube test | differentiation among urobilinogen, porphobilinogen, and ehrlich reactives |
| addition of ehrlich reagent to urine produces a __________________ color enhanced by _____________ | cherry red color; sodium acetate |
| hoesch reagent: | ehrlich reagent in 6M HCl |
| false positives in hoesch test can be caused by | methyldopa, indican, pigmented urine |
| clinical significance of nitrite | cystitis, pyelonephritis, evaluation of antibiotic therapy, UTI |
| nitrite test principle | griess reaction |
| griess reaction | nitrite reacts with aromatic amine to form a diazonium salt that then reacts with tetrahydro benzoquinoline to form a pink azo dye |
| nitrite sensitivity | 100,000 organisms/ mL |
| leukocyte esterase advantage | can detect lysed leukocytes |
| clinical significance of LE | UTI |
| causes of false positives for LE | formalin, strong oxidizing agents, highly pigmented urine |
| causes of false negatives for LE | crenation from high SG, inaccurate timing |
| specific gravity is based on | pKa (dissociation constant) of a polyelectrolyte in an alkaline medium |
| indicator for pH | bromothymol blue |
Created by:
kingsleya27