The laboratory test selected for the discussion is a urine analysis (urinalysis). This analysis includes a series of laboratory screening tests to detect specific cells and substances (crystals and casts) in a patient’s urine. The reason for urinalysis is a necessity to support a diagnosis regarding urinary tract infections, kidney disease, problems with liver function, and diabetes among other conditions (McCance, Huether, Brashers, & Rote, 2015). In this case, a urinalysis is planned for diagnosing a urinary tract infection.
The sensitivity and specificity of urinalysis are usually different for various conditions and tests. While conducting tests to diagnose a urinary tract infection, it is possible to observe low sensitivity (lower than 50%) and high specificity (higher than 60%) for determining bacteria and nitrites, and high sensitivity (higher than 60%) and low specificity (lower than 50%) for determining leukocyte esterase and white and red blood cells (Bates, 2013; Laosu-Angkoon, 2013). While referring to data regarding nitrites and leukocyte esterase, it is possible to state that this analysis is not valid to diagnose urinary tract infections without additional testing.
A complete urinalysis includes three stages that are the physical examination of the urine, the chemical examination, and the microscopic examination. Firstly, a urine sample is assessed in terms of its color, concentration, odor, and cloudiness (Bates, 2013). Secondly, a plastic stick is used for examining whether it changes its color to indicate the presence of some chemical substances (blood, protein, and glucose among others) (Mambatta, Jayalakshmi, Harini, Menon, & Kuppusamy, 2015). Thirdly, a drop of the urine is examined with the help of a microscope to look for abnormal blood cells, crystals, or epithelial cells among other changes (Laosu-Angkoon, 2013).
While conducting a urinalysis for diagnosing a urinary tract infection in adults, it is important to refer to the following ranges: color – light yellow to dark amber; pH – 4.5-8; clarity – clear; nitrites – negative; leukocyte esterase – negative; bacteria – absent; white blood cells – ≤2-5 WBCs/hpf; red blood cells – ≤2 RBCs/hpf; epithelial cells – ≤5 (Bates, 2013; Laosu-Angkoon, 2013). If there is any amount of bacteria, present leukocyte esterase and nitrites, increased white blood cells, and present red blood cells, it is possible to suggest a urinary tract infection (Frazee, Enriquez, Ng, & Alter, 2015).
For diagnosing other diseases, including liver disease and diabetes, it is also important to monitor increases in glucose (a normal range is ≤130 mg/d) and proteins (a normal range is ≤150 mg/d), as well as the presence of ketones and bilirubin (Bates, 2013; Laosu-Angkoon, 2013).
Potential interfering factors that can influence the urinalysis results include the consumption of certain medications, supplements, and food, as well as bacteria from a patient’s genital area and skin. To avoid contaminating a sample with bacteria and any substances, it is important to educate patients before conducting a test. A patient should inform a healthcare provider about medications and supplements he or she takes. A patient can also be asked to clean the genital area to receive a “clean-catch” sample (McCance et al., 2015). It is acceptable to obtain a sample in the office of a healthcare provider to minimize the time before taking a sample and conducting a test. Post-testing education is usually not required, and depending on results, patients can be asked to take other tests during a follow-up visit.
Bates, B. N. (2013). Interpretation of urinalysis and urine culture for UTI treatment. US Pharmacist, 38(11), 65-68.
Frazee, B. W., Enriquez, K., Ng, V., & Alter, H. (2015). Abnormal urinalysis results are common, regardless of specimen collection technique, in women without urinary tract infections. The Journal of Emergency Medicine, 48(6), 706-711.
Laosu-Angkoon, S. (2013). The sensitivity and specificity of a urine leukocyte esterase dipstick test for the diagnosis of urinary tract infection in the outpatient clinic of Rajavithi Hospital. Journal of the Medical Association of Thailand, 96(7), 849-853.
Mambatta, A. K., Jayalakshmi, V. L., Harini, S., Menon, S., & Kuppusamy, J. (2015). Reliability of dipstick assay in predicting urinary tract infection. Journal of Family Medicine and Primary Care, 4(2), 265-270.
McCance, K. L., Huether, S. E., Brashers, V., & Rote, N. S. (2015). Pathophysiology: The biologic basis for disease in adults and children (7th ed.). St. Louis, MO: Mosby Elsevier.