Urine dipstick

Note: Urinalysis (UA) can be done at bedside (dipstick) or in laboratory, this page will focus on bedside (dipstick)

Specific Gravity (Normal 1.003-1.030)

• Related to serum/urine osmolality (kidney's ability to concentrate or dilute urine)
• <1.003
  • Excessive hydration
  • Nephrogenic diabetes insipidus
  • gGomerulonephritis
  • Pyelonephritis
  • Acute tubular necrosis
• Fixed levels 1.010
  • End stage renal disease
  • Chronic glomerulonephritis
• >1.030
  • Dehydration
  • SIADH
  • Adrenal insufficiency
  • Other: Liver failure, nephrotic syndrome, and prerenal renal disease
• False decrease glycosuria, proteinuria, IV contrast, urine contamination

pH (Normal 5.5-6.5)

• High pH
  • Vegetarians
  • UTI (urea-splitting bacteria)
  • Alkalemia (metabolic vs. respiratory)
  • Type 1 renal tubular acidosis
  • Drugs (Salicylate, antibiotics, acetazolomide)
• Low pH
  • High protein-fat diet
  • Acidemia (normal renal response)
  • Diabetes, DKA
  • Starvation
  • Diarrhea
  • Metabolic disorder (Phenylketonuria)

Protein (Negative-Trace)

• Dipstick positive at 5-10mg/dL (normal to have <150mg/dL protein per day)
• High protein
  • Renal
    • Renal tubular secretion, increased filtration, pyelonephritis, glomerulonephritis, znephrotic and nephritic syndrome
  • Drugs
    • Aminoglycosides, gold, amphotericin, NSAID, sulphonamides, penicillins
  • CHF
  • Preeclampsia
  • Other: Pregnancy, physiologic stress, exercise, fever, cold exposure
• Mostly detects albumin, so may NOT detect
  • Bence Jones globulin (multiple myeloma, lymphoma, and macroglobulinemia)
  • Microalbuminuria (30-300 mg/day)
• Can be affected by dilution (check urine concentration)

Leukocyte Esterase (Negative)

• Associated with pyuria >10WBC per hpf
• Positive
  • Contamination
  • Trichomonas vaginalis
  • Drug/foods that colour urine red
• False negative
  • Less than 30 seconds to 2 minutes of urine contact
  • Low bacteria count
  • Gycosuria, proteinuria, high specific gravity

Nitrite (Negative)

• Requires 4h of incubation within bladder with >10,000 gram-negative bacteria (E. coli) per mL urine
• False positive
  • Exposure to air (1/3 false positive after one week, 3/4 at two weeks)

Blood (Negative)

• Peroxidase activity
  • Hematuria
    • Trauma, infection, inflammation, calculi, neoplasm, clotting disorder, burns, cold, eclampsia, sick cell crisis, transfusion reaction, exercise, and infarction
  • Hemaglobinuria (intravascular hemolysis)
  • Myoglobinuria (crush injury, electrocution, rhabdomyolysis)
  • Ascorbic acid or antiseptic povidone iodine (Betadine)
• Diets high Vitamin C can result in false negative (affects peroxidase activity)

Glucose (Negative)

• Usually detected in urine when serum levels >180mg/dL
  • Hyperglycemia diabetes, Cushing’s disease, liver disease, and several congenital/metabolic conditions
  • Renal disease (failure to resorb glucose in proximal tubule)
  • Drugs (cephalosporins, penicillins, nitrofurantoin, methyldopa, tetracycline, lithium, carbemazepine, phenothiazines, steroids and thiazides)

Ketones (Negative)

• Low carbohydrate (high fat/protein) diets, starvation,
• diabetes, alcoholism, hyperthyroidism, and eclampsia
• Overdose
  • Insulin, isoniazid, and isopropyl alcohol
• Underestimates ketonemia (nitroprusside less sensitive than beta-hydroxybutyric acid - the predominant ketone in DKA)

Bilirubin (Negative)

• Raised conjugated bilirubin (water soluble)
  • Hepatocellular disease
  • Cirrhosis
  • Hepatitis
  • Biliary obstruction
  • Inherited

Urobilinogen (0.2-1.0 mg/dL)

• Positive (Bilirubin turnover)
  • Hemolysis, Malaria
  • Liver disease
• Decreased or absent
  • Bile duct obstruction
  • Specific antibiotics