UA chemical test lab//lect

dipstick steps

dipstick possible errors

• Dipping too long.

• Not removing excess urine.

• Timing incorrectly.

• Not mixing urine and missing formed elements that sink to the bottom.

• Strips are protected from heat, light, and chemicals.

• The bottle must have a desiccant to take out moisture.

• Store dipsticks at room temperature.

why we mix urine

Formed elements, such as red blood cells, white blood cells, and casts, can settle at the bottom. If you do not mix the sample, you might miss them.

What should you do before testing urine with a reagent strip?

mix the urine

QC does what

Checks that the reagent strips are working correctly before patient results are reported.

QC done

uDipsticks are tested with control solutions

uControl Level – negative control

uControl Level – positive control

uBoth a positive and negative reaction should be seen.

uDone every 24 hours and with each new bottle/ lot of reagent strips

Which medication can interfere with urine dipstick reactions because it strongly colors the urine?

Pyridium- turns urine orange or reddish-orange= possible interference, must use confirmation test

What should be considered when urine pigmentation makes a dipstick result difficult to interpret?

Use an appropriate confirmation test

What can protein in urine indicate?

Possible kidney damage or renal disease

Proteinuria caused by a problem before blood reaches the kidneys is:

prerenal

Proteinuria caused by glomerular damage is:

renal

Protein entering urine from bladder inflammation is:

postrenal

Where is albumin produced?

liver

What is a major function of albumin?

maintains blood oncotic

what protiens screened in dip stick

only albumin. SSA screening test may require for other proteins detection

transferrin

transport iron in the blood

tamm-horsfall protein

normal urinary glycoprotein made by renal tubules

multistix

detects albumin best, less sensitive to other proteins, SSA test detect a wider range of proteins in the urine

Bence Jones proteinuria is classified as which type in the traditional classification of proteinuria?

Prerenal

Memory tip: Multiple myeloma → plasma cells → light chains → Bence Jones proteins → prerenal proteinuria.

At what temperature do Bence Jones proteins traditionally precipitate?

A. 0–10°C B. 40–60°C C. 100°C only

B. 40–60°C

A patient has Bence Jones proteins in the urine. Which result is possible?

A. Negative Multistix, positive SSA

B. Positive Multistix, negative SSA always

C. Both tests must be negativ

A. Negative Multistix, positive SSA

neg multistix protein result mean

proteinuria may still be there

limitations of dipstick proteins

1. mainly detects albumin

2. false-positive= highly alkaline urine

3. false neg = other protein go undetected

4. highly pigmented urine

5. timing reading error

All protein methods measure the amount of protein or albumin in urine, but this does not take into consideration the patient's hydration state.

• Dehydration: Urine becomes more concentrated, which can make protein concentration appear higher.

• Overhydration: Urine becomes more diluted, which can make protein concentration appear lower.

• 24-hour urine total protein test: Measures the total amount of protein excreted over 24 hours. It has been used to assess kidney damage, but collection can be time-consuming and inconvenient.

physical examination

evaluates color, clarity, odor, and specific gravity.

chemical examination

uses reagent strips and backup or confirmation tests when initial results are questionable or interfering substances may cause false-positive or false-negative results.

microscopic examination

examines cells, casts, crystals, microorganisms, and other formed elements.