What is the relationship of urinary bilirubin and urobilinogen to the diagnosis of pre-hepatic disorders?
Increased breakdown of Hgb causes increased levels of conjugated bilirubin which cause an increase in urinary urobilinogen and no urinary bilirubin.
What is the relationship of urinary bilirubin and urobilinogen to the diagnosis of hepatic (hepatocellular) disorders?
Liver is unable to remove reabsorbed urobilinogen from the portal circulation causing increased urinary urobilinogen (or may be absent) and increased urinary bilirubin (varies).
What is the relationship of urinary bilirubin and urobilinogen to the diagnosis of post hepatic disorders?
Intra/extra-hepatic obstruction decreases the normal amount of bilirubin being excreted into the intestinal tract, which causes an increase in urinary bilirubin (spills over) and no urinary urobilinogen (decreased).
What is the clinical significance of a positive urine test for nitrite?
Indicates presence of bacteria in significant numbers due to infection of the urinary system.
How is a positive nitrite result confirmed?
Microscopic examination (urine sediment)
What is the clinical significance of a positive urine test for leukocyte esterase?
Indicates increased number of WBCs in urine (may be due to infection/inflammation of genitourinary system).
What is the relationship between specific gravity and osmolality with regard to urine concentration?
SG indicates the proportion (ratio) of dissolved solids to the total volume of the specimen (relative degree of concentration).
Osmolality is a count of the number of particles in a fluid sample (urine/serum).
(Greater concentration=higher osmolality).
What is the significance of the presence of RBCs in urinary sediment? What can cause this finding?
Indicates bleeding in the urinary tract (without significant proteinuria).
Caused by urinary tract stones, benign/malignant UT neoplasms, trauma, prostatitis.
What is the significance of the presence of WBCs in urinary sediment (pyuria)?
Indicates presence of infection/inflammation of the genitourinary system.
What does moderate/heavy proteinuria, WBC casts and hematuria most likely indicate?
What is the significance of the presence of squamous epithelial cells in urine?
<5 cells/hpf means "clean" sample
Most frequently seen and least clinically significant.
What is indicated by a urine sample with large numbers of squamous epithelial cells (>10 cells/hpf)? What can this sample not be used for?
Indicates a poorly collected sample.
Cannot be sent to micro lab for culture (contaminated).
What is indicated when a urine sample shows large numbers of transitional epithelial cells? What could be expected if the normal indication is not the case?