Chapter 2: Urine Preservatives Flashcards
• Acceptable for routine urinalysis for 24 hr
• Acceptable for urine culture; inhibits bacterial growth for ~24 hr
• Inexpensive
Refrigeration
• Precipitates solutes in amorphous and/or crystalline forms (i.e., urates, phosphates)
Refrigeration
Storage before and after testing
Refrigeration
• Acceptable for routine urinalysis; preserves chemical and formed elements in urine at room temperature
• Boric acid preservative is also acceptable for urine culture
Commercial transport tubes
• pH and SG may be altered;
varies with tube used
• Can interfere with chemistry tests (e.g., sodium, potassium, hormone, drug assays)
Commercial transport tube
• Urine transport from off-site to laboratory
• Preserve specimen at room temperature for longer time period; varies with tube used
Commercial transport tube
• Preserves sediment elements (e.g., casts, cells)
• Inhibits bacterial and yeast growth
Thymol
• Interferes with protein precipitation tests
• In high concentration, can precipitate crystals
Thymol
• Sediment preservation
Thymol
Excellent cellular preservative
Formalin
False-negative reagent strip tests for blood and urobilinogen
Formalin
Cytology
Formalin
Saccomanno’s fixative
• Potential chemical hazard
Saccomanno’s fixative
• Excellent cellular preservative
• Commercially available and inexpensive
Saccomanno’s fixative
• Inexpensive
• Stabilizes calcium, phosphorus, steroids, hormones, etc.
Acids (HCI, glacial acetic acid)
• Unacceptable for urinalysis
• Potential chemical hazard
Acids (HCI, glacial acetic acid)
• For quantitative analysis of testing urine solutes, such as steroids hormones, etc.
Acids (HCI, glacial acetic acid)
• For quantitative analysis of porphyrins, porphobilinogen, etc
.
• Unacceptable for urinalysis testing
• Inexpensive
• Stabilizes porphyrins, porphobilinogen, etc
Sodium carbonate
