Core Lab Study
To screen urine for multiple markers to assist in diagnosing disorders such as urintary tract infections (UTIs), kidney and liver disease, as well as to assess hydration status.
A small group of studies in this manual have been identified as Core Lab Studies. The designation is meant to assist the reader in sorting the basic “always need to know” laboratory studies from the hundreds of other valuable studies found in the manual—a way to begin putting it all together.
Normal, abnormal, or various combinations of core lab study results can indicate that all is well, reveal a problem that requires further investigation with additional testing, signal a positive response to treatment, or suggest that the health status is as expected for the associated situation and time frame.
Urinalysis is another of the most commonly ordered laboratory studies. Its popularity is based on the wide range of clinical information it can provide, ease of collection (noninvasive), low cost, and availability in most settings.Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction. As appropriate, provide the required urine collection container and specimen collection instructions.
Method: Macroscopic evaluation by dipstick and microscopic examination. Urinalysis comprises a battery of tests including a description of the color and appearance of urine; measurement of specific gravity and pH; and semiquantitative measurement of protein, glucose, ketones, urobilinogen, bilirubin, hemoglobin (Hgb), nitrites, and leukocyte esterase. Urine sediment may also be examined for the presence of crystals, casts, renal epithelial cells, transitional epithelial cells, squamous epithelial cells, white blood cells (WBCs), red blood cells (RBCs), bacteria, yeast, sperm, and any other substances excreted in the urine that may have clinical significance. Examination of urine sediment is performed microscopically under high power, and results are reported as the number seen per high-power field (hpf).
- Normal Physical Characteristics of Urine
- Color: ranges from light yellow to deep amber and depends on:
- the patient’s state of hydration (more concentrated samples are darker)
- medication regimen
- exposure to other substances or foods may contribute to unusual color.
- Appearance: Clear Cloudiness is sometimes attributable to the presence of amorphous phosphates or urates as well as blood, WBCs, fat, or bacteria.
- Odor: Varies by individual, but generally urine does not have a strong odor. In the case of dehydration, the urine is more concentrated and may have a stronger, almost ammonia-type odor; exposure to other substances or foods may also contribute to unusual odor (e.g., asparagus)
|Up to 1 mg/dL
|Less than 5/hpf
|Less than 5/hpf
|Rare; usually no clinical significance
|Rare hyaline; otherwise, none seen
|Crystals in acid urine
|Uric acid, calcium oxalate, amorphous urates
|Crystals in alkaline urine
|Triple phosphate, calcium phosphate, ammonium biurate, calcium carbonate, amorphous phosphates
|Bacteria, yeast, parasites
Critical Findings and Potential Interventions
Possible critical findings are the presence of uric acid, cystine, leucine, or tyrosine crystals.
The combination of grossly elevated urine glucose and ketones is also considered significant.
Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.
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