Clinical biochemistry II - exam 2

What does bright yellow urine indicate

multivitamins, riboflavin

what does yellow-orange/green/brown urine indicate

bilirubin, urobilin, biliverdin

what does red urine indicate

hemoglobin, red blood cells, porphyrins, myoglobin, certain drugs beets (genetic)

what does red-brown urine indicate

hemoglobin, red blood cells, myoglobin, methemoglobin

what does green/blue-green urine indicate

methylene blue, some urine antiseptics, biliverdin

what does milky white urine indicate

fat bacteria, white blood cells

what does brown/black urine indicate

homogentisic acid, melanin, certain drugs

what does cloudiness in urine indicate

WBCs, RBCs, EPIs, bacteria, amorphous material (precipitated salts), phosphates (white), urates (pink)

what does ammonia smelling urine indicate

decomposition of urea, splitting bacteria

what does fruity smelling urine indicate

ketones, might be seen with diabetes mellitus

what does foul smelling urine indicate

urinary tract infection

relationship between specific gravity of urine and volume of urine

inversely related, when sp is high the urine is more concentated

fixed specific gravity (isothenuric)

1.010, can indicate renal damage, lack of ability to dilute or concentrate urine

hypothenuria

diabetes insipidus, absence of/or impairment of antidiuretic hormone, loss of concentration ability/large urine volume with low sg

hyperthenuria

urine with a high specific gravity ( diabetes mellitus)

pH of urine

normal: 5-8

clinical significance: acid base balance, UTI, renal calculi

protein in urine

normal: neg-trace

clinical significance: renal disease, UTI

glucose in urine

normal: neg

clinical significance: diabetes mellitus

ketones in urine

normal: neg

clinical significance: diabetes mellitus, starvation

blood in urine

normal: neg

clinical significance: glomerular disease, trauma, hemolytic anemias

bilirubin in urine

normal: neg

clinical significance: liver disease, biliary obstruction

urobilinogen in urine

normal: 1 mg/dl

clinical significance: liver disease, hemolysis

nitrites in urine

normal: neg

clinical significance: UTI

leukocyte esterase in urine

normal: neg

clinical significance: UTI

specific gravity of urine

normal: 1.003-1.030

clinical significance: kidneys concentration ability

double buffer system

principle for urine pH testing

protein error of indication

principle of urine protein testing

glucose oxidase

principle of urine glucose testing

sodium nitroprusside reaction

principle of urine ketone testing

peroxidase activity of hemoglobin and myoglobin

principle of urine blood testing

diazo reaction

principle of urine bilirubin testing

ehrlich’s reaction

principle of urine urobilinogen testing

granulocytic esterase reaction

principle of urine leukocyte esterase testing

urine pH false positive

pH increase due to contaminant bacteria

urine pH false negative

pH decrease due to run over from protein pad

urine protein false positive

highly alkaline urine from contaminant bacteria

urine protein false negative

dilute urines, proteins other than albumin

urine glucose, blood, bilirubin, and nitrite false negative

ascorbic acid

urine blood false positive

menstrual contamination, betadine contamination

urine nitrite false positive

contaminant bacteria

urine leukocyte false positive

vaginal discharge contamination

urine leukocyte false negative

high specific gravity inhibits esterase release from WBCs

pyuria

presence of increased WBCs in urine

casts

structures unique to the kidney

form when proteins “gel” within the distal tubule

factors promoting cast formation

decreased urine flow rate

low pH

high solute concentration

high protein content

hyaline casts

clear, colorless, cylinders possessing parallel sides

associated with fever, exercise, pure carb diet, dehydration therapy, and renal disease

RBC casts

if present the kidney can be identified as the source of the bleeding

result of glomerular membrane damage or tubular damage

have a classic red brown color

WBC casts

seen with inflammation of the kidney, classically with acute pyelonephritis

waxy casts

very refractile and may have a slight yellow cast to them

associated with renal failure

broad casts

often seen with other types of casts

wider than other casts and most form in the distal tubules and collecting ducts that have been damaged causing them to widen

fatty casts

contain lipid droplets or oval fat bodies

often seen with the severe proteinuria associated with the nephrotic syndrome

polarizing light may be used to identify

calcium oxalate crystals

envelope appearance

associated with urinary calculus formation

uric acid crystals

football appearance

seen in dehydration and gout patients receiving chemotherapy

ammonium biurate crystals

yellow brown thorn apple appearance

rare normal crystal

calcium carbonate crystals

small dumbbell appearance

rare normal crystal

calcium phosphate crystals

large thin flat plates

rare normal crystal

triple phosphate crystals

colorless coffin lid pyramid or prism appearance

crystine crystals

stop sign appearance

results from congenital defect of renal tubular reabsorption

leucine crystals

yellow brown with concentric circles

highly refractile

often seen with tyrosine in liver disease

is rapidly destroyed by bacteria

tyrosine crystals

fine needle like sheaves

may be seen with leucine in patients with faulty amino acid metabolism and in liver disease

sulfa crystals

sheaves of wheat appearance

highly refractile

uncommon due to increased solubility of current generation of sulfa drugs

cholesterol crystals

colorless plates with broken notched or cut off corners

rarely seen unless urine has been refrigerated

bilirubin crystals

highly colored yellow brown

confirm with positive icotest

radiographic dyes crystals

may resemble other crystals

urine will have high specific gravity (>1.040)

Jaffe reaction

measurement of creatinine

involves picric acid in an alkaline solution combining with creatinine to form a red compound that is measured spectrophotometrically

carraway method

measurement of uric acid

inulin clearance test

inulin is freely filtered and not secreted or reabsorbed

inulin is not naturally occurring in the body and must be infused intravenously

creatinine clearance test

most widely used test for the evaluation of GFR

the test involves collection of a 24 hr urine sample

(U x V)/ (P x 1440) x 1.73/SA

Acute glomerulonephritis

Large, inflamed glomeruli with a decreased capillary lumen Rapid onset of hematuria & proteinuria

Chronic glomerulonephritis

Glomerular scarring & eventual loss of functioning nephrons Gradual development of uremia may be first sign

nephrotic syndrome

associated with massive proteinuria, hypoalbuminemia, edema, hyperlipidemia, and lipiduria

tubular disases

results in decreased excretion/reabsorption of certain substances or reduced concentrating capability

transudates

fluids of noninflammatory origin with a normal composition but an increased volume caused by alterations in hydrodynamic factors such as: hypoproteinemia, relative increase in venous pressure, salt and fluid retention, lymphatic blockage

exudates

fluids of inflammatory origin characterized by increased protein concentration, fibrinogen is present and fluid may clot, many leukocytes, glucose concentration is decreased, bacteria may be present, blood may be present from hemorrhage or tumor

monosodium urate crystals

seen in gout

looks like needles