Instructions for reading normal urine test results

The article was professionally consulted by MSc Do Thi Hoang Ha - Doctor of Biochemistry, Laboratory Department - Vinmec Hai Phong International General Hospital. The doctor has 11 years of experience working in the field of clinical biochemistry.

Urine is the most important excretory fluid, containing most of the waste products of the body, so urine test indicators are used to monitor the function of some organs in the body, diagnose and treat diseases. monitor and treat many diseases such as: insipidus, diabetes, ketosis, urinary tract infections, liver, kidney, bile, hematuria, early detection of pregnancy poisoning,...

Urinalysis will give specific indicators such as:
pH Urine density Glucose urine Bilirubine Nitrite Protein WBCs Urobilinogen Red blood cells Ketones Ascorbic Acid In which, urine density and pH have specific values. , and other indicators such as white blood cells, nitrite, protein,... have very low concentrations or almost none appear in the urine. If the result is negative, it means that there is no abnormal presence of the substance in the urine and conversely, if the result is positive, it indicates a high risk of the patient for related diseases.

The white blood cell index is based on the presence of granulocyte esterase enzyme present in the urine, ester hydrolysis as well as indoxylation occurs to produce a product that changes color on the urine test strip (to Violet).
Permissible index: No white blood cell or white blood cell count 10-25 Leu/UL. The sensitivity of the test decreases with time due to leukocyte lysis.
A negative result when <25 RWB/uL indicates no abnormal presence of leukocytes in the urine. This test is very sensitive, so the rate of false negatives is very rare (common when the urine glucose, ascorbic acid and proteinuria are very high), but if the clinical manifestations are obvious, it is necessary to combine the results of the Protein and nitrite test results. To assess.
Abnormal white blood cells in the urine reflect the presence of bacteria in the urine (bladder infection, urinary tract infection). Follow-up should be performed, if necessary, additional testing should be performed (urine culture). The test is false positive when formaldehyde is present in the sample, the specimen is contaminated.

Normally, nitrite is not present in the urine, only occurs when Gram-negative bacteria are present in the urine and a reaction occurs to convert nitrate to nitrite. Taking a urine sample to measure Nitrite must be in the correct order, taken when the urine has been in the bladder for ≥ 3.5 hours (for nitrate to be converted to nitrite).
Nitrite index test is based on a Griess test specific to nitrite, which reflects the presence of bacteria that make up nitrite.
Positive nitrite index: ≥ 0.06 mg/dL.
A negative result when <0.06 mg/dL indicates the absence of gram-negative bacteria in the urine. Some cases of false negative due to the presence of gram-positive bacteria, insufficient urine collection time in the bladder, insufficient nitrate food (due to lack of green vegetables), high urine concentration of ascorbic acid, patients taking antibiotics. Therefore, it is necessary to consider in the clinical setting, in combination with white blood cell count, urine culture and multiple tests to give accurate results.
A positive result indicates a urinary tract infection (usually caused by Gram-negative bacteria). Samples left untested and contaminated for too long can also cause false positives.

In people with normal renal function, no protein is present or only a small amount of protein in the urine (in the form of albumin and globulin) is mainly plasma albumin because the glomerular membrane does not allow protein molecules to be present. large molecular weight pass through, so there is not enough to have a positive reaction. The urine protein test is performed on a concentrated urine sample, based on the change in protein concentration with a pH indicator.
Permissible indicators: trace (trace); ≤ 10 mg/dL or ≤ 0.1 g/L.
A negative result (Negative when 0.0 - 4.0 mg/dL) indicates the absence of albumin (because the dipstick is more sensitive to albumin), does not exclude the presence of hemoglobin, globulin, mucoprotein, Bence body. Jones Protein in urine.
Repeatedly positive results may be due to urinary tract infection, kidney disease, preeclampsia, high blood pressure, congestive heart failure,... It is necessary to consider the accompanying tests (quantification of proteinuria on the sample). 24-hour urine). False positive results if patient has hematuria, urine is excessively concentrated, polyvinylpyrrolidone injection, urine container containing chlorhexidine, quaternary ammonium bleach.

Normally, glucose is not present in the urine because it is completely reabsorbed in the proximal tubules, and the kidneys have a "renal threshold" for glucose. Only when blood glucose exceeds the renal threshold, or the renal absorption of sugar is reduced, will glucose appear in the urine. The urine glucose test is based on a specific glucose oxidase/peroxidase reaction.
Allowable index: 0-100 mg/dL or 2.5-5 mmol/L (common for pregnant women).
A negative result (Negative) indicates no abnormal presence of Glucose in the urine. In patients with diabetes, additional fasting blood glucose testing is required for evaluation.
Positive results indicate the risk of nephrogenic diabetes, diabetes mellitus, renal tubular disease, pancreatitis, diet too high in sugar, infection, multiple myeloma, pheochromocytoma.
The test may be false positive when the patient uses antibiotics, corticosteroids, non-glucose sugars. A false-negative phenomenon occurs when the patient has high levels of ascorbic acid and urinary ketones.

Normally, there is very little ketone in the urine, for people with uncontrolled diabetes, there will be a lack of insulin so that the body cells cannot use glucose as an energy source but must use other energy sources. substitutes - usually fatty acids. The metabolic products of these fatty acids are ketone bodies of three main types, in which the urine ketone test is more sensitive to acetoacetate. As a result, the presence of ketones in the urine helps aid in the diagnosis of diabetes as well as in the assessment of conditions causing the ketoacidosis (such as excessive fasting or starvation)
Cause-based testing According to Legal guidelines, Allowable Ketone Index: 2.5-5 mg/dL or 0.25-0.5 mmol/L.
A negative result is normal, no further testing is required.
Positive results indicate a high risk of diabetes, alcohol abuse, fever or diarrhea, or after the use of anesthetics (postanesthesi). False-positive cases occurred when the patient was taking bromo-sulfophthalein, phenolphthalein and its metabolite L-dopa.
Ketonic test results need to combine glucose results, avoiding the case of omission when the results are inconsistent.

Normally, Urobilinogen is a metabolic product of conjugated bilirubin (direct bilirubin) by enteric bacteria in the duodenum, excreted mainly in the feces, and appears in the urine in low concentrations, increasing in cases of infection. severe infection, G6PD deficiency disease, hemolytic anemia, liver dysfunction, excessive rupture of red blood cells. Urobilinogen test results need to be combined with bilirubin results for differential diagnosis.
Test based on Ehrlich reaction (in combination with diazonium salt), Permissible index: 0.2-1.0 mg/dL or 3.5-17 mmol/L.
A negative result (normal range 0.1-1 EU/dL) does not indicate an abnormality, no further testing is required. False negatives may occur if the urine is left out for too long or the patient is taking antibiotics.
Positive results need to do more tests to evaluate hepatobiliary function as well as anemia due to hemolysis. False-positives may occur due to atypical coloration, para-aminosalicylic acid, or patients with porphyria.

Bilirubin is the result of hemoglobin degradation, although direct bilirubin can pass through the glomerular membrane, but under normal conditions, bilirubin will not be detected in the urine because it has been converted to urobilinogen in the intestine. An abnormal presence in the urine of bilirubin indicates a risk of liver disease, or disease of the bile ducts (which results in bilirubin not reaching the intestines, entering the bloodstream, being filtered by the kidneys, and excreted in the urine).
Allowable index: ≤ 0.2 - 0.4 mg/dL or ≤ 3.4 - 6.8 mmol/L.
A negative result is normal, no other test is needed. False negatives appear if the urine test is left in the light for a long time, and the concentration of ascorbic acid in the urine is high.
Positive results should be combined with urobilinogen test for differential diagnosis. Phenothiazide and chlorpromazid, salicylates may cause false-positive results.

Normally in the urine there is no presence of blood (red blood cells, hemoglobin, myoglobin). The presence of red blood cells in the urine indicates a patient's risk of urinary tract infection or kidney disease.
Permissible index: 0.015-0.062 mg/dL or 5-10 Ery/UL.
A negative result is normal, if a high-risk patient needs a repeat urinalysis to check. A false negative occurs when formaldehyde is present in the urine.
Positive results need to be combined with other test results for diagnosis. Persistent positive results in people over 40 years of age may be due to urothelial cancer (bladder cancer, renal cell carcinoma). A false-positive test occurs if a woman is on her period, is exercising heavily, has high levels of ascorbic acid in her urine, the container is contaminated with antiseptics, the urine has been left for too long, or is washing the perianal area with water. povidon.

When the result of 20 mg/dL Ascorbic Acid in the urine is positive, otherwise it is negative. High concentrations of ascorbic acid in the urine can cause false negatives for glucose, blood, leukocytes, nitrite, and bilirubin (tests based on oxidative stress because ascorbic acid (vitamin C) is an antioxidant. antioxidant). Urine ascorbic acid results help reduce the risk of misinterpretation of test results in certain conditions. The test can be false positive when the patient consumes a lot of vitamin C in the diet.
Permissible index is from 5-10 mg/dL or 0.28-0.56 mmol/L.

Urine density helps assess the ability of the kidneys to concentrate and dilute. Normal urine density is about 1.005 – 1.030.
Increased urine density is associated with dehydration (syndrome of inappropriate antidiuretic hormone secretion), profuse vomiting, diabetes mellitus, acute diarrhea, profuse vomiting, fever ..
Decreased urine density is related to excess water (renal dysfunction, aldosterol syndrome),

Urine pH provides information regarding a patient's acid-base status. Normal pH is in the range of 5.0 - 7.0
Alkaline urine condition (pH > 7.0) can occur when the patient eats a lot of vegetables, urinary tract infections, kidney infections, bladder infections.
Acidic urine status (pH < 5.0) can occur when the patient eats a lot of meat, exercises a lot of muscles, has acute diarrhea, is malnourished or has metabolic disorders in diabetes..
Thus, the result of each indicator in the urine test has its own meaning. The test results may need to be combined with other tests to diagnose the related disease.
Vinmec International General Hospital is one of the hospitals that not only ensures professional quality with a team of leading medical doctors, modern equipment and technology, but also stands out for its examination and consultation services. comprehensive and professional medical consultation and treatment; civilized, polite, safe and sterile medical examination and treatment space. Customers when choosing to perform tests here can be completely assured of the accuracy of test results.