Urine testing

Question 1

Glucose/ketones

Answer 1

Detection:
glucose - rxn with glucose oxidase
ketones - nitroprusside rxn detects acetaldehyde and acetone

Gluc elevated when: serum > 10 mmol/L (DM)
Renal tubular resorption defect (renal glycosuria)

Ket elevated in: diabetic ketoacidosis (gluc + ketones in urine), also fasting states

Question 2

Nitrites/WBC

Answer 2

Nitrite elevated: bacteria with nitrate reductase activity (first morning urine best)

WBC present: inflammation - intact & lysed leukocytes have leukocyte esterase

Question 3

Hematuria

Answer 3

Blood detected by: peroxidase-like activity due to Hb
+ indicates: hematuria, hemoglobinria or myoglobinuria
can be false + with elevated ascorbic acid

Causes: hematologic (coagulopathy, sickle cell anemia), renal (glomerular, non-glomerular), post-renal (kidney stones, tumour downstream, cystitis)

Question 4

Proteinuria

Answer 4

Change in osmotic concentration –> change in ionic strength –> colour change in pH in a sensitive dye
Normal <150 mg/day

Causes:

• glomerular
• tubular
• overflow proteniuria

Question 5

Hematuria + proteinuria indicates

Answer 5

glomerulonephritis

Question 6

RBC cast

Answer 6

distinct red cells

glomerular injury, renal bleeding

Question 7

Hyaline cast

Answer 7

non-specific transparent

dehydration, fever, exercise

Question 8

Coarse granular cast

Answer 8

coarse refractile granules

cell degeneration/proteinuria

Question 9

fine granular cast

Answer 9

semitransparent

nonspecific

Question 10

Calcium oxalate

Answer 10

acidic, neutral to slightly alkaline crystal

also can be due to: increased uric acid levels, decreased urinary citrate levels, distal renal tubular acidosis

Question 11

Triple phosphate - urine

Answer 11

AKA struvite stones
Ammonium magnesium phosphate
Some bacteria are able to split urea –> ammonia, increase urine pH
Reduce solubility of magnesium ammonium & phosphate
Alkaline urine
UTI (Proteus, Klebsiella, Pseudomonas)
Staghorn calculi

Question 12

Uric acid crystals

Answer 12

Acidic urinary pH (Diarrhea)
Dehydration
Uricosuric drug (salicylates, thiazides)
high protein diet
increased serum uric acid levels (gout, leukemia, chemotherapy)

Question 13

Cysteine in urine

Answer 13

Cystinuria
Inherited defect in renal tubular resorption of cysteine, ornithine, lysine, arginine
acidic urine
hexagonal crystals

Question 14

RBC in urine

Answer 14

Usually <3 /hpf
trauma, malignancy, cystitis, infections, prostatitis
Dysmorphic RBCs: RBC of glomerular/renal origin
- damaged during gromerular/tubular passage

Question 15

WBC in urine

Answer 15

Usually <1 / hpf

UTI, inflammation