21 - Urinalysis Flashcards Preview

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Flashcards in 21 - Urinalysis Deck (49):

What are the three parts of a urinalysis?

- gross exam (look at it, macroscopic)
- dipstick
- microscopic


What are the meanings of different colors of urine (macroscopic appearances of urine??

- Brown (bile pigments, or patient taking dopa)
- Orange (bile pigments, or taking pyridium)
- Cloudy (UTI, or patient eats purine rich diet)
- Green/blue (psuedomonal infection, or patient taking tagamet)


What else do you look for macroscopically?

Also grossly look for stones, odor, cloudiness


Describe a dipstick test

- Plastic stick with a number of reagents that is “dipped” into urine sample.
- The colors are either compared manually by a tech or are analyzed by a computer


Describe a urine pH test

- Normal urine pH 4.5 - 8
- High pH = alkalosis, UTI
- Low pH = acidosis, starvation, dehydration

The pH of the urine usually reflects what is going on in the body


Describe proteinuria

- Under normal circumstances, with normally functioning kidneys, protein is not excreted in amounts detectable by dipstick and should be negative in dipstick.


What causes proteinuria?


DM, preeclampsia, multiple myeloma, nephrotic syndrome, uti, blood, muscle breakdown (exercise), illness or stress

In reality, trace amounts in my world tells me very little


What does glucose in the urine mean?

- Typically the kidneys will reabsorb the glucose until the blood sugar gets > 300
- Then the kidneys are overwhelmed


What causes glycosuria?


- Can be benign
- Can be situational (dehydration, pregnancy, stress)
- DM, cushings, liver, pancreatic disease *****
- Renal dysfunction *****



Can you diagnose diabetes based on urinalysis?



What causes blood in the urine (hematuria)


- Trauma ***
- Menses ***
- Blood thinners ***
- UTI ***
- Renal Stones (10% no hematuria) ***
- Cancer in the renal system ***
- Often benign (very common) ***

Without microscopic UA, hard to know at all what this means


Describe the clinical interpretation of hematuria


- One episode mild hematuria, let go. If continued, deserves a work up.
- In a trauma patient, or a patient that has been on the ground for a long time, blood without RBCs can mean rhabdomyolysis *****

BLOOD BREAK DOWN (no whole RBCs, meaning blood is being broken down in the body)


What does gross hematuria look like?

Red or brown blood


What do kidney stones look like on CT?

White - they look like bone


What is specific gravity?

- High means concentrated
- Low mean dilute…renal disease, well hydrated


Describe leukocyte esterase in the urine


- From the breakdown of wbc
- Can indicate UTI, but overly sensitive
- Positive with “dirty” clean catch, std, etc

In a female with leukocyte esterase in the urine, only 50% will actually have an infection


What do nitrites in the urine mean?


Gram negative bugs produce an enzyme named reductase that converts nitrates to nitrites.

*** Very specific, low sensitivity for UTI ***


What does it mean if there is bilirubin in the urine?


- When water-soluble (conjugated) bilirubin passes through the kidneys.
- Hemolytic anemia ***
- Bile obstruction ***
- Hepatitis ***


What does it mean if there is urobilirubin in the urine?


- End product of conjugated bilirubin after metabolized by intestines
- Can be seen in hemolysis and in liver disease ***
- Can be falsely positive in UTI with positive nitrites.


What things do you look for in the microscopic exam?

- Crystals
- Casts


What do crystals indicate?

- Can indicate kidney stone or one is forming


What do casts indicate?

- Clumps of material or cells

Not testing on this


What do they count on the microscopic exam?


RBCs counted

If RBCs present, can be from exercise, sickle cell, meds, UTI, stone, cancer

Gross hematuria - menses, CA, UTI ***

10% of renal stones no blood or RBCs


So give a summary of how you analyze blood

So the dipstick detects blood products (whole or parts) and the microscopic sees red cells


What else do we count on microscopic exam?

WBCs counted
- 5 or less ok for women
- 2 or less for men

More usually indicates UTI


What does bacteria in the urine mean on a microscopic exam?


- Over 5 in women significant in CLEAN catch
- Any in men significant

Any on a catheter specimen significant ***


What do epithelial cells in a microscopic exam indicate?

- None, few, moderate, many
- Can be from “dirty” catch (much more common in women), UTI, cancer


What other miscellaneous organisms do we see?

- Yeast
- Trichomonos
- Now urine tests for Chlamydia


No we will focus on diagnosing UTI



What are the "easy call" UTI diagnoses?

- + LE, + nitrites
- Packed WBCs, moderate to many bacteria


What is a "tough call" UTI?

- Few LE
- Negative nitrites
- WBCs
- Bacteria
- Epithelial cells present
- Definitely send for cx for final dx


What are the three most common causes of post-op fever?


*** Atelectesis (lung collapse)
*** Surgical infection (wound)
*** UTI (patient gets foley cath during surgery)


Describe a urine pregnancy test

- The hospital/clinic tests not much (if any) better than store…detects about 10 days past ovulation or few days prior to menses
- Home tests more prone to user error (read too soon, test too early)


Describe a blood pregnancy test

- Blood tests slightly more sensitive, but presurgery/office standard is still urine beta-hcg


When should you get a urine pregnancy test?

- You get these on all women with any possibility of pregnancy going to surgery, possibly CT and possibly when giving drugs that are not ok in pregnancy (valium, levaquin)


Describe a drug screen test

- People who use drugs usually don’t want to donate urine
- Frequently won’t change treatment
- “Tox screen”…hospitals aren’t the FBI
- Date rape drugs…tests aren’t readily available in DSM hospitals
- Can have false positives
- People lie about using; people lie about not using
- Police generally don’t care about hospital’s results – can’t use them in typical settings
- K2/bath salts don’t show up (new drugs)


Why are drug screens important for you?

- There are patients you will want to screen prior to surgery and/or narcotics


Describe amphetamines on a urine drug screen

- 30 – 120 hours
- False positives - ADHD meds, diet pills, decongestants, vics inhalers, trazadone and even Zantac

Some have both amphetamine and methamphetamine – anesthesia cares if this is positive


Describe opiates on a urine drug screen

- Shows codeine, morphine (heroine metabolized to morphine).
- Poppy seeds, DXM false positive possible
- Fentanyl, darvocet doesn’t show up (Chicago deaths)
- Hydrocodone, percocet, dilaudid may or may NOT show up (depending on how people metabolize it)


What other drugs can you see on a drug screen?

- Barbiturates
- Benzos
- Cocoaine


Describe barbiturates on a urine drug screen

- Used for sedation or anti-seizure
- Kind of "out of style"
- No false positives


Describe benzos on a urine drug screen

- 2-4 days
- Some short-acting ones are harder to catch


Describe THC on a urine drug screen

- 7-30 days
- Passive inhalation has NOT been shown to test positive


Describe cocaine on a urine drug screen

- 8-48 hours
- Some herbal teas can cross react


Describe PCP on a urine drug screen

Dexamethoraphan (?) Dxm


Describe a case of urinalysis

- 40 y/o male presents to ER with styrofoam cup full of a brown liquid that looked like coffee with cream
- Trapped raccoons for a living
- Had nausea


What did his urinalysis show?

- Fresh sample showed + bili and + urobili + mild protein
- CBC normal
- Electrolytes, glucose, kidney function normal
- LFT’s 100X normal (liver function on overdrive)


What was the diagnosis?


Most people have had this, he just got really sick from it


What is "beeturia"

Urine turns red after eating beets – only affects about 10% of population