108.3

straw, yellow, dark yellow

normal, common reportable urine colors

amber, orange, red, brown, green

abnormal, common reportable urine colors

urochrome

pigment that gives urine the normal yellow color

darker=more concentrated

relationship of urine color to concentration

urine appears bright orange, dipstick testing cannot be used

How does phenazopyridine affect urinalysis

bilirubin

amber urine; yellow foam appears when shaken

biliverdin

yellow-green urine

uroerythrin

pink, amorphous phosphates

urobilin

orange-brown urine

RBCs

cloudy, red urine

hemoglobin or myoglobin

clear, red urine

Oxidation of porphobilinogen to porphyrias

Port wine-colored urine

homogentisic acid - metabolite of phenylalanine; found in metabolic inborn error and alkaline urine (alkoptonuria)

melanina - excess in malignant melanoma; oxidation of melanogen to melanin

2 pathological causes of black or brown urine

blood has oxidized; maybe glomerular bleeding

Brown urine tests positive for blood

negative for blood

What test result is warranted before considering if a brown-black urine may contain melanin or homogentistic acid?

urinary bacterial infection

Pathological cause of blue or green urine

ingested materials

Nonpathological cause of blue or green urine

clear, hazy, cloudy, turbid, milky

common terminology to report urine clarity

phosphates: white (alkaline)

urates: pink (acidic)

pH test

Differentiate between appearance of amorphous phosphates and urates in refrigerated specimen. What chemical test is used for differentiation?

RBCs

WBCs

Bacteria

Yeast

Nonsquamous epithelial cells

Abnormal crystals

Lymph fluid

Lipids

pathological causes of cloudy urine

squamous epithelial cells

mucus

contamination

refrigerated speciment

amorphous phosphates and urates

nonpathological causes of cloudy urine

abnormal color, tested positive for formed elements (protein, blood, nitrates, leukoesterase

When should a microscopic exam be performed on clear urine?

determines tubule concentrating ability; whether sample is concentrated enough for chemical tests to be accurate

Why is specific gravity clinically significant?

measures velocity of light in air vs in solution

How do refractometers measure specific gravity?

measure conccentration through pH; more concentrated = more release of hydrogen ions = lower pH

How do reagent strips measure specific gravity?

measures colligative properties and compares to control to determine concentration; only measure particle number, not weight

How do osmometers measure specific gravity?

refrigerated to formed elements

cloudy urine with low specific gravity

probably not urine, actually

urine with specific gravity of 1.001

Hyposthenuric urine

SG lower than 1.010 consistently

Hypersthenuric urine

SG higher than 1.010 consistently

Isosthenuric urine

SG of 1.010 consistently

readiographic contract media (IVP)

Patient just returned from radiology has abnormally high specific gravity

plasma expander (Dextran)

Patient recently treated for a severe hemorrhage

no correction necessary for high protein and glucose

Advantages of measuring specific gravity with reagent strip and osmolality

1 g/dL glucose = 0.004 subtracted from specific gravity

glucose correction for refractometer

1 g/dL protein = 0.003 subtracted from specific gravity

protein correction for refractometer