Medgeeks Clinical Lab Guide Flashcards
Once a urine specimen is collected, what is the first thing that should be assessed?
Odor and color of the urine sample
Common causes of abnormal urine coloration: cloudy
Pathology: -Phosphaturia -Pyuria -Chyluria -Lipiduria -Hyperoxaluria Food and drug causes -Diet high in purine-rich foods (hyperuricosuria)
Common causes of abnormal urine coloration: brown
Pathology: -Bile pigments -Myoglobin Food and drug causes -Fava beans -Levodopa -Metronidazole -Nitrofurantoin -Some antimalarial agents
Common causes of abnormal urine coloration: brownish-black
Pathology: -Bile pigments -Melanin -Methemoglobin Food and drug causes: -Cascara -Levodopa -Methyldopa -Senna
Common causes of abnormal urine coloration: green or blue
Pathology: -Pseudomonal UTI -Biliverdin Food and drug causes: -Amitriptyline -Indigo carmine -IV cimetidine -IV promethazine -Methylene blue -Triamterene
Common causes of abnormal urine coloration: orange
Pathology: -Bile pigments Food and drug causes: -Phenothiazines -Phenazopyridine
Common causes of abnormal urine coloration: red
Pathology: -Hematuria -Hemoglobinuria -Myoglobinuria -Porphyria Food and drug causes: -Beets -Blackberries -Rhubarb -Phenolphthalein -Rifampin
Common causes of abnormal urine coloration: yellow
Pathology: -Concentrated urine Food and drug causes: -Carrots -Cascara
Common causes of cloudy urine
Pyuria
Phosphate crystals
Medical conditions that cause odor in urine
Fruity or sweet- diabetic ketoacidosis Ammonia- urine sample has been held in the bladder for an extensive period of time Pungent odor- UTI Fecal odor- intestinal-urologic fistula Sulfur smell- cysteine decomposition
Bilirubin false positives in urine
Phenazopyridine
Bilirubin false negatives in urine
Chlorpromazine
Selenium
Blood false positives in urine
Dehydration Exercise Hemoglobinuria Menstrual blood Myoglobinuria
Blood false negatives in urine
Captopril Elevated specific gravity pH < 5.1 Proteinuria Vit C
Glucose false positives in urine
Ketones
Levodopa
Glucose false negatives in urine
Elevated specific gravity
Uric acid
Vit C
Ketones false positives in urine
Acidic urine Elevated specific gravity Mesna Phenolphthalein Some drug metabolites
Ketones false negatives in urine
Delay in examination of urine
Leukocyte esterase false positives in urine
Contamination
Leukocyte esterase false negatives in urine
Elevated specific gravity Glycosuria Ketonuria Proteinuria Some oxidizing drugs Nitrofurantoin Tetracycline Vit C
Nitrites false positives in urine
Contamination
Exposure of dipstick to air
Phenazopyridine
Nitrites false negatives in urine
Elevated specific gravity Elevated urobilinogen levels Nitrate reductase-negative bacteria pH < 6.0 Vit C
Protein false positives in urine
Alkaline or concentrated urine
Phenazopyridine
Quaternary ammonia compounds
Protein false negatives in urine
Acidic or dilute urine
Primary protein is not albumin
Specific gravity false positives in urine
Dextran solutions
IV radiopaque dyes
Proteinuria
Specific gravity false negatives in urine
Alkaline urine
Urobilinogen false positives in urine
Elevated nitrite levels
Phenazopyridine
What does a specific gravity in urine tell?
Tells us about the pt’s hydration
If the specific gravity of urine is < 1.010
The pt is well hydrated
If the specific gravity of urine is >1.020
The pt is relatively dehydrated
What can increased specific gravity indicate?
Excess sugar or glucose in the urine related to uncontrolled diabetes, or DKA
SIADH
Causes of decreased urinary specific gravity
Diabetes insipidus
Adrenal insufficiency
Hyperaldosteronism
