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Day 3 Self Urinalysis TP, Blood, Nitrate & pH. Lungs and kidneys are major regulators of acid- base content First morning specimen slightly acidic at.

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Presentation on theme: "Day 3 Self Urinalysis TP, Blood, Nitrate & pH. Lungs and kidneys are major regulators of acid- base content First morning specimen slightly acidic at."— Presentation transcript:

1 Day 3 Self Urinalysis TP, Blood, Nitrate & pH

2 Lungs and kidneys are major regulators of acid- base content First morning specimen slightly acidic at 5.0 to 6.0 Postprandial specimen more alkaline Normal range is 4.5 to 8.0 No absolute values are assigned Urine pH

3 Considerations include – Acid-base content of the blood – Patient’s renal function – Presence of a urinary tract infection – Patient’s dietary intake – Age of the specimen A pH above 8.5 is associated with an aged/improperly preserved specimen, so a fresh specimen should be obtained Urine pH (cont’d)

4 Respiratory or metabolic acidosis/ketosis Respiratory or metabolic alkalosis Defects in renal tubular secretion and reabsorption of acids and bases—renal tubular acidosis Renal calculi formation Treatment of urinary tract infections Precipitation/identification of crystals Determination of unsatisfactory specimens Summary of Clinical Significance of Urine pH

5 Needed to measure between 5.0 and 9.0 in one half or one unit increments Double-indicator system reaction –Methyl red = 4 to 6 red/orange to yellow – Bromthymol blue = 6 to 9 green to blue Methyl red + H + → Bromthymol blue − H + (Red/Orange → Yellow) (Green → Blue) Interference –No known substances interfere with urinary pH measurements performed by reagent strips –RUNOVER from Protein pH-Reagent Strip Reactions

6 Most indicative of renal disease – Proteinuria seen in early renal disease Normal = <10 mg/dL or 100 mg/24 h Low-molecular-weight serum proteins are filtered; many are reabsorbed Albumin is primary protein of concern Other proteins include – Vaginal, prostatic, and seminal proteins – Tamm-Horsfall (uromodulin) Protein

7 Presence requires determination of normal or pathological condition Clinical proteinuria = 30 mg/dL, 300 mg/24 h Variety of causes – Prerenal – Renal – Postrenal Clinical Significance

8 Conditions affecting the plasma, not the kidney Transient, increase levels of low-molecular- weight plasma proteins, acute phase reactants, exceed reabsorptive capacity Rarely seen on reagent strip (not albumin) Prerenal Proteinuria

9 Multiple myeloma (plasma cell myeloma) Immunoglobulin light chains Multiple myeloma confirmation is serum electrophoresis Bence Jones Protein (BJP)

10 Glomerular or tubular damage – Glomerular proteinuria – Microalbuminuria – Orthostatic (postural) proteinuria – Tubular proteinuria Renal Proteinuria

11 Damage to glomerular membrane Impaired selective filtration causes increased protein filtration leading to cellular excretion Abnormal substances deposit on the membrane – Primarily immune disorders result in immune complex formation Lupus erythematosus, streptococcal glomerulonephritis – Amyloids and other toxins Glomerular Proteinuria

12 Hematuria: intact RBCs – Cloudy red urine Hemoglobinuria: product of RBC destruction – Clear red urine Any amount of blood greater than five cells per microliter of urine is considered clinically significant Chemical tests for hemoglobin provide the most accurate means for determining the presence of blood The microscopic examination can be used to differentiate between hematuria and hemoglobinuria Blood

13 Hematuria: intact RBCs, cloudy red urine Damage to renal system – Renal calculi – Glomerular disease – Tumors – Trauma – Pyelonephritis – Exposure to toxic chemicals – Anticoagulants Blood (cont’d)

14 Hemoglobinuria: clear, red urine – Transfusion reactions – Hemolytic anemias – Severe burns – Infections/malaria – Strenuous exercise/RBC trauma – Brown recluse spider bites Hemoglobinuria may result from the lysis of red blood in dilute, alkaline urine Hemosiderin: yellow brown granules in sediment Blood (cont’d)

15 Myoglobinuria: heme-containing protein in muscle tissue; clear, red/brown urine – Rhabdomyolysis: muscle destruction Muscular trauma/crush syndromes Prolonged coma Convulsions Muscle-wasting diseases Alcoholism Drug abuse Extensive exertion Cholesterol-lowering statin medications Blood (cont’d)

16 Principle pseudoperoxidase activity of hemoglobin Catalyze a reaction between the heme component – Hemoglobin and myoglobin – Chromogen tetramethylbenzidine – Produce an oxidized chromogen Green-blue color Blood Reagent Strip Reactions

17 hemoglobin H 2 O 2 + chromogen ---------------  oxidized chromogen + H 2 O peroxidase Two charts corresponding to different reactions Free hemoglobin shows uniform color Intact RBCs show a speckled pattern on pad – Report: trace, small (1+), moderate (2+), large (3+) – Sensitivity 5 RBCs/μL Blood Reagent Strip Reactions

18 False-positive – Menstrual contamination, strong oxidizing agents, bacterial peroxidases False-negative – Ascorbic acid >25 mg/dL – High SG/crenated cells – Formalin – Captopril – High concentrations of nitrite – Unmixed specimens Blood Reaction Interference

19 Clinical significance Rapid screening test for the presence of urinary tract infection (UTI) – Cystitis (initial bladder infection) – Pyelonephritis (tubules) – Evaluation of antibiotic therapy – Monitoring of patients at high risk for urinary tract infection – Screening of urine culture specimens (in combination with LE test) Nitrite

20 Tests ability of bacteria to reduce nitrate (normal constituent) to nitrite (abnormal) Greiss reaction: nitrite reacts with aromatic amine to form a diazonium salt that then reacts with tetrahydrobenzoquinoline to form a pink azodye Correspond with a quantitative bacterial culture criterion of 100,000 organisms/mL Results: negative and positive Nitrite Reagent Strip Reaction

21 Acid para-arsanilic acid or sulfanilamide + NO 2 —————→ diazonium salt (nitrite) Acid diazonium salt + tetrahydrobenzoquinolin —————→ pink azodye Nitrite Reagent Strip Reaction (cont’d)

22 False-negative – Nonreductase-containing bacteria – Insufficient contact time between bacteria and urinary nitrate – Lack of urinary nitrate – Large quantities of bacteria converting nitrite to nitrogen – Presence of antibiotics – High concentrations of ascorbic acid – High specific gravity – Negative results in the presence of even vaguely suspicious clinical symptoms should always be repeated or followed by a urine culture Nitrite Reaction Interference

23 False-positive – Old specimens (bacterial multiplication) – Highly pigmented urine – Pink edge or spotting on reagent strip is considered negative – Check automated readers manually for color interference Nitrite Reaction Interference (cont’d)

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