Urine Analysis / Urinalysis is simply an analysis of the urine. It is a very common test that can be performed in many health care settings, including doctors’ offices, urgent care facilities, laboratories, hospitals, and even at home.
A urinalysis test is performed by collecting a urine sample from the patient in a specimen cup. Usually only small amounts (30-60 mL) may be required for urinalysis testing.
General urine examination includes macroscopic, chemical and microscopic urinalysis. The macroscopic analysis includes examination of urine appearance and colour. The chemical examination includes specific gravity, qualitative presence of proteins, blood, nitrites, glucose, ketones, bilirubin, urobilinogens, etc. The microscopic examination refers to the presence of erythrocytes, leukocytes, epithelial cells, cylinders, bacteria, crystals, etc.
A dipstick — a thin, plastic stick with strips of chemicals on it — is placed in the urine to detect abnormalities. The chemical strips change color if certain substances are present or if their levels are above normal. A dipstick test checks for:
- Acidity (pH). The pH level indicates the amount of acid in urine. Abnormal pH levels may indicate a kidney or urinary tract disorder.
- Concentration. A measure of concentration, or specific gravity, shows how concentrated particles are in your urine. A higher than normal concentration often is a result of not drinking enough fluids.
- Protein. Low levels of protein in urine are normal. Small increases in protein in urine usually aren’t a cause for concern, but larger amounts may indicate a kidney problem.
- Sugar. Normally the amount of sugar (glucose) in urine is too low to be detected. Any detection of sugar on this test usually calls for follow-up testing for diabetes.
- Ketones. As with sugar, any amount of ketones detected in your urine could be a sign of diabetes and requires follow-up testing.
- Bilirubin. Bilirubin is a product of red blood cell breakdown. Normally, bilirubin is carried in the blood and passes into your liver, where it’s removed and becomes part of bile. Bilirubin in your urine may indicate liver damage or disease.
- Evidence of infection. If either nitrites or leukocyte esterase — a product of white blood cells — is detected in your urine, it may be a sign of a urinary tract infection.
- Blood. Blood in your urine requires additional testing — it may be a sign of kidney damage, infection, kidney or bladder stones, kidney or bladder cancer, or blood disorders.
During this exam, several drops of urine are viewed with a microscope. If any of the following are observed in above-average levels, additional testing may be necessary:
- White blood cells (leukocytes) may be a sign of an infection.
- Red blood cells (erythrocytes) may be a sign of kidney disease, a blood disorder or another underlying medical condition, such as bladder cancer.
- Bacteria or yeasts may indicate an infection.
- Casts — tube-shaped proteins — may form as a result of kidney disorders.
- Crystals that form from chemicals in urine may be a sign of kidney stones.
Ions and trace metals
|Target||Lower limit||Upper limit||Unit||Comments||LOINCCodes|
|Nitrite||n/a||0 / negative||The presence of nitrites in urine, termed nitrituria, indicates the presence of coliform bacteria.||5802-4|
|Sodium(Na) – per day||150||300||mmol / 24 h||A urinalysis is frequently ordered during the workup of acute renal failure. Full kidney function can be detected through the simple dipstick method.||2956-1|
|Potassium(K) – per day||40||90||mmol / 24 h||Urine K may be ordered in the workup of hypokalemia. In case of gastrointestinal loss of K, the urine K will be low. In case of renal loss of K, the urine K levels will be high. Decreased levels of urine K are also seen in hypoaldosteronism and adrenal insufficiency.||2829-0|
|Urinary calcium(Ca) – per day||15||20||mmol / 24 h||An abnormally high level is called hypercalciuria and an abnormally low rate is called hypocalciuria.||14637-3|
|100||250||mg / 24 hours||6874-2|
|Phosphate(P) – per day||n/a||38||mmol / 24 h||Phosphaturia is the hyperexcretion of phosphate in the urine. This condition is divided into primary and secondary types. Primary hypophosphaturia is characterized by direct excess excretion of phosphate by the kidneys, as from primary renal dysfunction, and also the direct action of many classes of diuretics on the kidneys. Additionally, secondary causes, including both types of hyperparathyroidism, cause hyperexcretion of phosphate in the urine.||14881-7|
A sodium-related parameter is fractional sodium excretion, which is the percentage of the sodium filtered by the kidney which is excreted in the urine. It is a useful parameter in acute renal failure and oliguria, with a value below 1% indicating a prerenal disease and a value above 3% indicating acute tubular necrosis or other kidney damage.
Proteins and enzymes
|Target||Lower limit||Upper limit||Unit||Comments|
|mg/dl||Proteins may be measured with the Albustix test. Since proteins are very large molecules (macromolecules), they are not normally present in measurable amounts in the glomerular filtrate or in the urine. The detection of protein in urine, called proteinuria, may indicate the permeability of the glomerulus is increased. This may be caused by renal infections or by other diseases that have secondarily affected the kidneys, such as hypertension, diabetes mellitus, jaundice, or hyperthyroidism.|
|Human chorionic gonadotropin(hCG)||–||50||U/l||This hormone appears in the urine of pregnant women.And also in case of testicular cancer in male. Home pregnancy tests commonly detect this substance.|
|Target||Lower limit||Upper limit||Unit||Comments|
|Red blood cells (RBCs) /
High Power Field
|May be present as intact RBCs, which indicate bleeding. Even trace amount of blood is enough to give the entire urine sample a red/pink hue, and it is difficult to judge the amount of bleeding from a gross examination. Hematuria may be due to a generalized bleeding diathesis or a urinary tract-specific problem (trauma, stone…urolithiasis, infection, malignancy, etc.) or artefact of catheterization in case the sample is taken from a collection bag, in which case a fresh urine sample should be sent for a repeat test.If the RBCs are of renal or glomerular origin (due to glomerulonephritis), the RBCs incur mechanical damage during the glomerular passage, and then osmotic damage along the tubules, so get dysmorphic features. The dysmorphic RBCs in urine which are most characteristic of glomerular origin are called “G1 cells”, which are doughnut-shaped rings with protruding round blebs sometimes looking like Mickey Mouse’s head (with ears).
Painless hematuria of nonglomerular origin may be a sign of urinary tract malignancy, which may warrant a more thorough cytological investigation.
|RBC casts||n/a||0 / negative|
|White blood cells(WBCs) /
|–||10||per µl or
|“Significant pyuria” at greater than or equal to 10 leucocytes per microlitre (µl) or cubic millimeter (mm3)|
|n/a||0 / negative||dip-stick qualitative scale of 0 to 4+||Hemoglobinuria is suggestive of in vivo hemolysis, but must be distinguished from hematuria. In case of hemoglobinuria, a urine dipstick shows presence of blood, but no RBCs are seen on microscopic examination. If hematuria is followed by artefactual ex vivo or in vitro hemolysis in the collected urine, then the dipstick test also will be positive for hemoglobin and will be difficult to interpret. The urine color may also be red due to excretion of reddish pigments or drugs.|
|Target||Lower limit||Upper limit||Unit||Comments|
|Glucose||n/a||0 / negative||Glucose can be measured with Benedict’s test. Although glucose is easily filtered in the glomerulus, it is not present in the urine because all of the glucose filtered is normally reabsorbed from the renal tubules back into the blood. Presence of glucose in the urine is called glucosuria.|
|Ketone bodies||n/a||0 / negative||With carbohydrate deprivation, such as starvation or high-protein diets, the body relies increasingly on the metabolism of fats for energy. This pattern is also seen in people with diabetes mellitus, when a lack of the hormone insulin prevents the body cells from using the large amounts of glucose available in the blood. This happens because insulin is necessary for the transport of glucose from the blood into the body cells. The metabolism of fat proceeds in a series of steps. First, triglycerides are hydrolyzed to fatty acids and glycerol. Second, the fatty acids are hydrolyzed into smaller intermediate compounds (acetoacetic acid, betahydroxybutyric acid, and acetone). Thirdly, the intermediate products are used in aerobic cellular respiration. When the production of the intermediate products of fatty acid metabolism (collectively known as ketone bodies) exceeds the ability of the body to metabolize these compounds, they accumulate in the blood and some end up in the urine (ketonuria).|
|Bilirubin||n/a||0 / negative||The fixed phagocytic cells of the spleen and bone marrow destroy old red blood cells and convert the heme groups of hemoglobin to the pigment bilirubin. The bilirubin is secreted into the blood and carried to the liver, where it is bonded to (conjugated with) glucuronic acid, a derivative of glucose. Some of the conjugated bilirubin is secreted into the blood and the rest is excreted in the bile as bile pigment that passes into the small intestine. The blood normally contains a small amount of free and conjugated bilirubin. An abnormally high level of blood bilirubin may result from an increased rate of red blood cell destruction, liver damage (as in hepatitis and cirrhosis), and obstruction of the common bile duct as with gallstones. An increase in blood bilirubin results in jaundice, a condition characterized by a brownish-yellow pigmentation of the skin and of the sclera of the eyes.|
|Creatinine||4.8||19||mmol / 24 h|
|Urea||12||20||g / 24 h|
|Uric acid||250||750||mg / 24 h|
dopamine – per day
|90||420||μg / 24 hours|
|Free cortisol||28or 30||280or 490||nmol/24 h||Values below threshold indicate Addison’s disease, while values above indicate Cushing’s syndrome. A value smaller than 200 nmol/24 h (72 µg/24 h) strongly indicates absence of Cushing’s syndrome.|
|10or 11||100 or 176||µg/24 h|
|Phenylalanine||30.0||mg/L||In neonatal screening, a value above the upper limit defines phenylketonuria.|
Other urine parameters
|Test||Lower limit||Upper limit||Unit||Comments|
|Urine specific gravity||1.003||1.030||g/cc||This test detects the ion concentration of urine. Small amounts of protein or ketoacidosis tend to elevate the urine’s specific gravity (SG). This value is measured using a urinometer and indicates hydration or dehydration. If the SG is under 1.010, the patient is hydrated; an SG value above 1.020 indicates dehydration.|
|Osmolality||400||n/a||mOsm/kg||Urine osmolality testing can be used in conjunction with Plasma osmolality tests to confirm diagnosis of SIADH|
|Bacterial cultures||by urination||–||100,000||colony forming unitsper millilitre (CFU/mL)||Bacteriuria can be confirmed if a single bacterial species is isolated in a concentration greater than 100,000 CFU/ml of urine in clean-catch midstream urine specimens (one for men, two consecutive specimens with the same bacterium for women).|
|by bladder catheterisation||–||100||For urine collected via bladder catheterisation, the threshold is 100 CFU/ml of a single species.|
This test detects the presence of commonly used drugs such as
- benzodiazepines, and
Urine pregnancy test is very common and it measures a hormone in the urine associated with pregnancy (beta-HCG or beta- human chorionic gonadotropin). This test can be done in medical settings, but numerous kits are available for home use.
Other urine tests can also be used in evaluation of many medical conditions. Examples include
- urine culture (in determining the bacterial cause of urine infection),
- urine creatinine (in assessing kidney disease),
- urine total protein and albumin (in assessing kidney disease and protein loss from kidney),
- urine cytology (in evaluating for possible bladder or other urinary tumors),
- urine calcium (in evaluating elevated blood calcium levels),
- 24-hour urine collection for proteins (in diagnosing causes of kidney impairment, diabetic related kidney disease, lupus related kidney disease),
- 24-hour urine collection for protein electrophoresis (for measuring different components of proteins in urine in evaluating multiple myeloma, kidney inflammation with increased protein loss), or
- 24-hour urine collection of catecholamine metabolites (in evaluating adrenal gland disease, difficult to treat high blood pressure).
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