What actually is a urinalysis?
A simple screening test for:
-Kidney disease
-UTIs
-Other systemic diseases
What does glucose and/or ketones in the urine suggest
Diabetes / DKA (ketones)
What do proteins in the urine suggest
Most commonly, a problem with the glomerulus
What do nitrites in the urine suggest?
Infection - nitrites are produced by gram (-) bacteria
*Also look for WBCs, leukocytes, and bacteria
What does bilirubin in the urine sugget?
Liver disease
*Also may be (+) for blood due to hemolysis
What can cause blood in the urine?
-Stones
-Tumours
-Infection
-Glomerular lesions (look for dysmorphic RBCs, RBC casts, and proteinuria)
-Hemolysis
What does the specific gravity of the urine reflect?
Urinary concentration
What is rhabdomyolysis + it’s UA findings
Rapid breakdown of muscle
(+) for blood in the urine due to myoglobin excretion, but no RBCs
What are urinary casts?
Cylindrical structures formed in the renal tubules from Tamm-Horsfall protein (uromodulin) → often trap cells or debris (can help localize pathology)
Types of casts + significance (5)
-Hyaline: mostly normal - dehydration (concentrated urine), diuretics, exercise
-RBC casts: proliferative glomerulonephritis
-WBC casts: peylonephritis
-Waxy: non-specific (not diagnostic)
-Granular: tubular damage
Reporting of bacteria / crystals in urine
1+: present, but hard to find
2+: easy to find, not many but more than a few
3+: prominent
4+: packed/crowded with bacteria or crystals
What do calcium phosphate crystals in the urine indicate?
Kidney stones
What do tyrosine and/or leucine crystals in the urine indicate
Severe liver disease
What do struvite crystals in the urine suggest?
Infected stones
Urinalysis detects what proteins in urine?
Only albumin, and only when it’s >60 mg/L
Specific gravity effect on UA proteinuria
-Dilute urine (SG 1.005): shows “less” protein
-Concentrated urine (SG 1.030): shows “more” protein
Interpetation of SG + proteinuria
A urine dipstick of trace or +1 indicates significant proteinuria only if the SG is 1.025 or less
How to correct for concentration factor on proteinuria
Urine protein : Cr ratio → divide the urine protein by urine creatinine
How to calculate proteinuria per day
- Determine creatinine/day = weight x 0.15
- Multiply by the urine protein/Cr
Ex: urine PCR = 700, weight = 110
110 x 0.15 = 165
165 x 700 = 11,1150 mg proteinuria /day
Screening tool for kidney disease in diabetes
Urine albumin : Cr ratio
Albuminuria classifications
A1: <3 mg/mmol → normal
A2: 3 -29 mg/mmol → moderately increased
A3: >30 mg/mmol → severely increased
