Urine Analysis Flashcards
What is the significance of Specific Gravity in Urine Analysis?
Tells you the ability of the kidney to dilute or concentrate urine.
Any urine having a specific gravity over 1.035 is either contaminated, contains very high levels of glucose, or the patient may have recently received high density radiopaque dyes
What are the normal ranges for specific gravity in the urine?
Specific Gravity of 1.002 is max dilution, representing urine osmolality of 50-100 mOsm.
Sp. Gr. of 1.030 is max concentration, representing urine osmolality of 1200 mOsm.
Your patient has a urine specific gravity of 1.038. What is abnormal about this?
Any urine having a specific gravity over 1.035 is either contaminated, contains very high levels of glucose, or the patient may have recently received high density radiopaque dyes intravenously for radiographic studies or low molecular weight dextran solutions.
Your patient could be diabetic?
Normal pH range of urine.
5.0-6.5
Urine pH >7.5-8.0 suggests what?
a UTI with urea-splitting bacteria
(Proteus, E.coli)
High pH urine, think INFECTION.
What level of glucose will you find in a normal urine sample?
0
Under physiological conditions, glucose is 100% reabsorbed.
Hyperglycemia and Glucosuria indicate what type of abnormality?
Endocrine
Insulin resistance or lack thereof.
Glucosuria in the presence of normal blood glucose indicates what?
Proximal Tubule Dysfx.
Example: Hereditary Renal Glucosuria - mutation in SGLT2 transporter makes you unable to reabsorb glucose.
How do you assess glucosuria?
Dipstick
When would you see ketones in the urine?
Fasting states
Diabetic Ketoacidosis (DKA)
Alcoholic Ketoacidosis (AKA)
•Increased plasma ketoanions lead to filtered load exceeding proximal tubular reabsorptive capacity, resulting in ketonuria
Positive Nitrite in the urine suggests what?
(We usually secrete ________ in the urine. Not nitrite.)
UTI with nitrate reducing bacteria
We usually secrete nitrAte. Not nitrIte
A positive leukocyte esterase indicates what?
Leukocyte esteras is a neutrophil-specific enzyme.
Infection of Lupus.
What component is in every urine cast?
Tam-Horsfall protein
(Low MW protein)
A spot urine sample of 5 means what?
5 grams of protein were urinated in a 24 hour period.
What is the threshold for calling protein in the urine “Proteinuria?”
3.5 g/ day
Proteinuria indicates damage where in the kidney?
Glomerular capillary wall.
The dipstick proteinuria test is specific for which protein only?
Albumin
What test detects ALL protein in the urine, including small molecular weight proteins like light chains?
Sulfosalicylic acid test.
A negative dipstick for proteins in the urine, but a positive sulfosalycylic acid test means what?
There is overflow proteinuria of small molecular weight proteins in the blood.
They all filter, and exceed the resporptive capacity of the proximal tubule, where proteins are usually reabsorbed.
Example: Multiple Myeloma has filtered light chains called Bence Jones proteins.
When do you measure Urine Anion Gap?
What will it tell you?
When there is no plasma anion gap.
In cases of Hyperchloremic Metabolic Acidosis.
It will either be positive (kidney malfunction = RTA 1, 2, or 4)
or negative = GI HCO3- loss or malabsorption of something
What amount of RBCs can be found in urine under normal physiological conditions?
0-2 rbc/highpowerfield
And urine dipstick is negative for blood.
How do you know whether hematuria is renal/non-renal?
CASTS are the main thing.
what is a glitter cell? When do you see it?
White blood cells in the urine are glitter cells.
Bigger than an RBC but smaller than an epithelial cell.
Seen in UTI, pyelonephritis, etc…
What cells are these? Pathologic/Nonpathologic?
Squamous epithelial cells.
Found in the lower urinary tract (urethra)
What kind of cell is this?
Renal tubule epithelial cells.
Clumps of them seen in ACUTE TUBULAR NECROSIS
When would you see these in the urine? What are they?
Hyaline cast: non-pathologic.
Seen in normal, volume depleted urine.
(marathon runner pees after running a race, and not adequately hydrating)
What is the definition of a urinary cast?
Precipitates of proteins and cellular compoenents that form solid casts of the tubule they form in.
All have Tamm-Horsfall protein in them (form the framework)
Urinary casts are formed only in the ______________ and ________________ part of the nephron.
Casts only form in the DISTAL CONVOLUTED TUBULE and COLLECTING DUCT.
The proximal convoluted tubule and the loop of Henle aren’t sites of cast formation.
What factors favor protein cast formation in the tubules?
Low flow rate, High salt concentration, and low pH.
What can you clearly determine from this patient’s urine sample?
He has Chronic Kidney Disease
WAXY CASTS are distinctive for Chronic Kidney Disease.
See the WHITE OUTLINE? Hyaline casts don’t have that. And the blunt, torn edges.
What are these?
Uric acid crystals.
These can be seen in normal, old, or frozen urine samples because it ppts out.
Excessive amounts seen in gout patients?
What are these?
Calcium oxalate crystals.
Most common kidney stones form from this material
ENVELOPES
What are these?
Triple Phosphate crystals
COFFIN LIDS
What disease does this patient have?
CYSTEINURIA
Stop signs are always pathologic.
Associated with VERY dense stones, and VERY hard to treat.
Lipidurea indicates what?
Nephrotic syndrome - always associated with hyperlipidemia
Urine will be frothy too.
What term is associated with the fatty casts seen with Nephrotic Syndrome?
How do you visualize them?
Maltese crosses in the fatty casts.
Viewed with POLARIZED LIGHT
What kind of cast is this?
Lipid casts
Nephrotic syndrome
What kind of cast is this? What disease/process is associated with it?
Granular cast
Not specific for any disease, but seen commonly in acute tubular necrosis
What kind of disease does this patient have?
RBC casts indicate glomerular disease.
Glomerulonephritis!! Nephritic syndrome!
What does this person probably have?
Acute Pyelonephritis
WBC cast
