Ann Bartlett recently informed me that there are many questions about components in the urine! We recently discussed the importance of ketones in urine and now I want to talk about the relationship of diabetes to the compounds that may be present in urine. Typical urine constituents may include glucose, ketones, blood, red blood cells, white blood cells, leukocyte esterase, nitrates, bacteria, and protein. The key is to understand how these players help to diagnose an underlying medical issue.
- Glucose: present in the urine if the blood glucose threshold is approximately greater than or equal to 180 mg/dl. Therefore, if there is glucose in the urine, we know that at some recent time, blood glucose has exceeded 180 mg/dl. However, urinary glucose is "old news," and blood glucose readings are much more temporally accurate. Glucose in the urine is often the first culprit to lead to the suspicion of diabetes; however, further evaluation including blood glucose is mandatory to confirm the diagnosis.
- Ketones: see past blog.
- Blood: may be present in the urine for either benign or pathological reasons. Menstruation in women is a common cause. Blood also may be present secondary to a bladder issue (infection, other medical problems). The clinician must ask the appropriate questions to determine the significance of blood in the urine, in both men and women. It would be appropriate to obtain a urine culture if there are symptoms of a urinary tract infection (UTI).
- Red blood cells: may be present if there is irritation or infection in the genito-urinary region. Once again, menstruation, infection, or other medical problems may be the source. Your healthcare team will need to investigate.
- White blood cells: often present in a urinary tract infection as above and further urine evaluation will be necessary.
- Leukocyte esterase, nitrates and bacteria: often are markers of a urinary tract infection and, if present, the physician will take a urine culture. Keep in mind that bacteria may just be a contaminant and only the presence of a pure colony (usually greater than 100,000 organisms in a clean catch specimen) will be considered a UTI and need to be treated with antibiotics that are sensitive to the organism.
- Protein: a common component in the urine. In diabetes, protein in the urine may be an important indicator of impending nephropathy or kidney problems. However, protein in the urine may truly have a benign source, especially in children, teens, and young adults who are active. Protein in the urine (or Proteinuria) may be secondary to "orthostatic proteinuria," which is of no medical consequence. Orthostatic proteinuria occurs when one is up and about all day, walking around, or very active in terms of physical exertion such as sports or other activities. Thus, if protein is found in the urine on a routine urinalysis, I suggest checking for protein in a first morning urination. If the issue is "orthostatic proteinuria," the urine should not show any protein upon awakening.
In people with diabetes for at least 5 years and after age 10, we check a "random urine for microalbumin /creatinine ratio" to check for protein in the urine related to diabetes. If the random urine microalbumin/creatinine ratio is greater than "30 micrograms albumin/mg creatinine," I then do an overnight sample in which I ask the person with diabetes to go to the bathroom before bed, collect any samples in a container if they wake up in the middle of the night, and then collect the first morning sample. In this way, I rule out "orthostatic proteinuria." If the sample is still abnormal (greater than 30 micrograms albumin/mg creatinine) I will do a 24-hour collection. If the 24-hour collection is abnormal, I will then consider the person to have microabuminuria if the result is between 30-300 micrograms albumin/mg creatinine. If the child/adolescent has microalbuminuria, I will generally refer to our pediatric nephrologists who will most likely start either an ARB (Angiotensin II Receptor Blocker) or ACE (Angiotensin Converting Enzyme inhibitor) medication that should reverse the microalbuminuria before nephropathy ensues. We then check urines intermittently for resolution of the microalbuminuria. Urine microalbumin/creatinine ratios greater than 300 micrograms albumin/mg creatinine is no longer considered to be "microalbuminuria" and is a much more serious problem.
The goal, however, is to prevent the development of pathologic protein in the urine (proteinuria) by tightening up blood sugar control with frequent blood glucose monitoring and appropriate insulin therapy. As you all should be aware, the lowering of hb A1c has been demonstrated by the Diabetes Control and Complication Trial to markedly decrease the incidence of nephropathy!
If you have any further questions in regard to urinary components, feel to ask in the comment section so information will be available to all!
Published On: April 26, 2011