Disease Associations

Disease Associations:
Different conditions will present with different biochemical and urinary sediment results. Let’s break down a few common conditions seen in urinalysis.

Glomerulonephritis:
Glomerulonephritis is a renal disorder caused by inflammation to the glomeruli. This can be an acute or chronic condition.

Acute
Positive blood and protein biochemical tests
RBCs and WBCs can be seen
RBC and/or hemoglobin casts

Chronic
Positive blood and protein biochemical tests
RBCs, WBCs, and renal tubular epithelial cells can be seen
Granular and waxy casts can be seen

Nephrotic syndrome:
Nephrotic syndrome is increased permeability of the glomerulus.

This can lead to hypoalbuminemia because albumin can now fit and exit in the urine.
Hyperlipidemia
Positive protein biochemical test
Presence of free fat and oval fat bodies
All kinds of casts can be present especially fatty, waxy, and renal

Pyelonephritis (kidney infection):
Pyelonephritis is an acute or chronic infection of the upper urinary tract involving the interstitial tissues or kidney.

Slight to moderately positive biochemical tests for protein, leukocytes esterase, and nitrite
WBCs, bacteria, and WBC casts can be present
WBC cast presence is considered pathognomonic for pyelonephritis

Lower urinary tract infection:

Infection of the urethra (urethritis) or bladder (cystitis)
Positive biochemical tests for leukocyte esterase and nitrite
WBCs, bacteria, and sometimes RBCs and renal tubular epithelial cells can be seen

Diabetes:
A microalbumin test detects small quantities of albumin in the urine. Albumin is one of the first proteins that will pass through into the urine when kidneys are damaged. The test can be used to detect early kidney problems for diabetic patients. In a 24 hour urine collection, less than 30ug/mL is normal, 30-300ug/mL indicates early kidney disease, and >300ug/mL indicates advanced kidney disease.

Cell types seen in urinalysis:

Epithelial cells:

Squamous cells (1:6 nuclear to cytoplasmic ratio) seen in large numbers are indicative of improper sample collection.
Transitional cells (1:3 nuclear to cytoplasmic ratio) seen in large numbers is indicative of disease.
Renal epithelial cells (1:1 nuclear to cytoplasmic ratio) seen in large numbers is indicative of disease.

RBCs:

RBCs present in the urine are due to injury, disease, or menstrual contamination.
Concentrated urine will give you crenated RBCs. (shriveled up)
Dilute urine (hypotonic) will give you ghost cells (swollen)
More than 2-3 RBCs per 400x microscope field is abnormal

WBCs:

WBCs present in the urine indicate infection or inflammation. WBCs enter the urinary system mostly through the glomerulus.
Hypotonic urine can have granule movement leading to the appearance of glitter cells.
A positive leukocyte esterase biochemical test is indicative of neutrophils.
WBCs can cause cloudy urine
WBCs and bacteria together are indicative of cystitis and pyelonephritis

Specific gravity:
Specific gravity in urinalysis is the ratio of the density of urine to the density of water. What does that mean?

Here’s an example:
Water has a density of 1000 kg/m3. Ice has a density of 916.7 kg/m3. In this case the specific gravity of ice is 916.7 kg/m3 / 1000 kg/m3 = 0.9167. Ok what does that mean? That means that 91.67% of ice will sink into water, or another way of thinking about it is 8.23% of ice will float. Next time you have some ice water you’ll notice how about 90% of it sinks. Ok what does this have to do with urine?

Urine specific gravity can be indicative of a disease or condition. Remember, water has a specific gravity of 1.000, so any urine sample around 1.000 will not have a lot of solutes in it. The range for urine specific gravity is 1.003-1.035.

Low specific gravity is associated with diabetes insipidus or renal diseases where the kidney can’t concentrate urine.

High specific gravity is associated with diabetes mellitus, proteinuria, dehydration, and diarrhea.

Isosthenuria and end stage renal disease:
Isosthenuria is a term used to describe urine whose specific gravity is about the same as protein-free plasma which is around 1.010. Combined with other symptoms, a specific gravity around 1.008-1.012 can indicate renal damage or end stage renal disease.