URINALYSIS Flashcards
pH normal range
4.5 - 8.0
Sources of Error: Falsely Alkaline and Acidic
Falsely Alkaline: bacterial growth
Falsely Acidic: improper reagent strip dipping
Source of Error: Leukocyte False Pos vs Neg
False Pos: coloured urine, contamination
False Neg: high [protein], [glucose], [ascorbic acid]; not mixing before dipping reagent strip
pH Significance
Acidosis or alkalosis with NORMAL KIDNEY FUNCTION
Nitrite False Pos vs Neg
False Pos: coloured urine, improper storage
False Neg: urine not held in bladder for long, high [ascorbic acid], high SG
Nitrite Significance
Gram negative bacteria infection
Leukocyte Significance
Infection/ inflammation
Protein False Pos vs Neg
False Pos: coloured urine, highly buffered alkaline urine, high SG, prolonged dipping of reagent strip
False Neg: proteins other than albumin
Glucose False Pos vs Neg
False Pos: contamination
False Neg: low temperature, high SG, high [ketones], high [ascorbic acid], bacteria
Protein Significance
Renal disease
Glucose Significance
Uncontrolled diabetes mellitus, renal disease, pregnancy
Ketones False Pos vs Neg
False Pos: coloured urine, bacteria, MESNA or captopril
False Neg: bacteria
Ketones Significance
Uncontrolled diabetes mellitus, inherited metabolic disorder, dieting, starvation
Blood False Pos vs Neg
False Pos: contamination, bacterial peroxidase, myoglobin
False Neg: high SG, high [ascorbic acid], not mixing before dipping reagent strip
Blood Significance
- Hematuria = renal stones, glomerulonephritis, pyelonephritis
- Hemoglobinuria = IVH, transfusion rxn, severe burns, infection
Urobilinogen Normal Range
< 16 μmol/L
Urobilinogen False Pos vs Neg
False Pos: coloured urine, porphobilinogen
False Neg: acidic urine, light exposure, RT storage
Urobilinogen Significance
Hemolytic disorders, liver disease (EXCEPT HEPATOBILIARY OBSTRUCTION)
Bilirubin Sources of Error
False Pos: coloured urine
False Neg: light exposure, 4°C storage, high [ascorbic acid], high nitrites
Bilirubin Significance
- HEPATOBILIARY OBSTRUCTION
- liver disease (hepatitis, cirrhosis)
SG Normal Range
1.005 - 1.030
SG Sources of Error
False Increase: high [proteins]
False Decrease: highly buffered alkaline urine
SG Significance
- hydration status
- increased SG = ketones
Describe pre-renal proteinuria
- increased low MW plasma proteins are excreted
- healthy glomeruli
- [proteins] exceed reabsorption capability of tubules
ie. acute phase reactants, hemoglobin/ myoglobin, monoclonal free light chains
Describe 2 types of renal proteinuria
- Glomerular leakage:
Selective =
- wider spaces between podocytes
- albumin (large MW) passes through damaged glomeruli, and excreted
Non-Selective = proteins of any size passes glomeruli
- Tubular proteinuria:
- healthy glomeruli
- tubules cannot reabsorb low MW β2-microglobulin and immunoglobulins
- caused by heavy metal poisoning (cadmium) and nephrotic drugs (gentamicin)
Describe post-renal proteinuria
originates from urinary tract due to inflammation, tumors, or injury
T or F: The reagent pad for blood detects both intact and lysed RBCs/ free hemoglobin
TRUE; The reagent pad for blood detects BOTH INTACT and LYSED RBCs/ free hemoglobin
Which positive macroscopic results require microscopic analyis ?
Blood, protein, nitrites, leukocytes
Stain used for urine sediments
Sternheimer-Malbin; supravital stain composed of safranin O and crystal violet
Where are narrow and broad casts formed ?
Narrow = distal tubule
Broad = collecting ducts
Hyaline casts are observed after __.
Hyaline casts are observed after STRESS or EXERCISE (dehydration)
Granular casts can be seen due to both __ and __.
Granular casts can be seen due to both EXERCISE and RENAL DISEASE.
Red blood cell casts indicate __, and is most commonly observed in __.
Red blood cell casts indicate BLEEDING IN THE NEPHRON, and is most commonly observed in GLOMERULONEPHRITIS.
White blood cell casts indicate __.
White blood cell casts indicate INFECTION/ INFLAMMATION WITHIN THE NEPHRON
White blood cell casts are observed in __.
White blood cell casts are observed in PYELONEPHRITIS, ACUTE INTERSTITIAL NEPHRITIS, and GLOMERULONEPHRITIS
Epithelial cell casts contain what kind of epithelial cells ?
Mostly RENAL TUBULAR epithelial cells
When are epithelial cell casts observed ?
- advanced renal tubular disease
- ingestion of heavy metals, drugs
- transplant rejection
- infection (pyelonephritis)