Urinalysis
Intervention

White blood cells seen under a microscope from a urine sample.
MeSH D016482
Other codes: LOINC Codes for Urinalysis panels

A urinalysis (UA), also known as Routine and Microscopy (R&M), is an array of tests performed on urine, and one of the most common methods of medical diagnosis.[1] The word is a portmanteau of the words urine and analysis.[2]

The target parameters that can be measured or quantified in urinalysis include many substances and cells, as well as other properties such as specific gravity.

A part of a urinalysis can be performed by using urine test strips, in which the test results can be read as color changes. Another method is light microscopy of urine samples.

Contents

Target parameters [link]

In addition to the substances mentioned in tables below, other tests include:

  • a description of color and appearance.

Ions and trace metals [link]

Target Lower limit Upper limit Unit Comments LOINC Codes
Nitrite n/a 0 / negative[3] The presence of nitrites in urine is termed Nitrituria, and indicates the presence of coliform bacteria.
Further information: Nitrite test
 5802-4
Sodium (Na) – per day 150[4] 300[4] mmol / 24hours The sodium levels are frequently ordered during the workup of acute renal failure. The fractional excretion of sodium, abbreviated as FeNa is an important marker in distinguishing pre-renal from post-renal failure. 2956-1
Potassium (K) – per day 40[4] 90[4] mmol / 24hours Urine potassium may be ordered in the workup of hypokalemia. In case of GI loss of potassium, the urine potassium will be low. In case of renal loss of potassium, the urine potassium levels will be high. Decreased levels of urine potassium are also seen in hypoaldosteronism and adrenal insufficiency. 2829-0
Urinary calcium (Ca) – per day 15[5] 20[5] mmol / 24hours An abnormally high level is called hypercalciuria and an abnormally low rate is called hypocalciuria.
Further information and more detailed ranges: Urinary calcium
 14637-3
100[5] 250[5] mg / 24 hours 6874-2
Phosphate (P) – per day n/a[4] 38[4] mmol / 24hours Phosphaturia is the hyperexcretion of phosphate in the urine. This condition is divided into primary and secondary types. Primary hypophosphatemia 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%[6] indicating acute tubular necrosis or other kidney damage.

Proteins and enzymes [link]

Target Lower limit Upper limit Unit Comments
Protein 0 trace amounts[3]
/ 20		 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 that the permeability of the glomerulus is abnormally increased. This may be caused by renal infections or it may be caused by other diseases that have secondarily affected the kidneys such as diabetes mellitus, jaundice, or hyperthyroidism.
Further information: Proteinuria
hCG
In non-pregnant adults		 – 50[7] U/L This hormone appears in the urine of pregnant women. Home pregnancy tests commonly detect this substance.

Blood cells [link]

Target Lower limit Upper limit Unit Comments
Red blood cells (RBCs) /
erythrocytes		 0[3][8] 2[3] – 3[8] per
High Power Field
(HPF)		 May be present as intact RBC which indicates 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, 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 and thus 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 (with ears).

Painless hematuria of nonglomerular origin may be a sign of urinary tract malignancy which may warrant a more thorough cytological investigation.

Further information: Hematuria
RBC casts n/a 0 / negative[3]
White blood cells (WBCs) /
leukocytes /
(pus cells)		 0[3] 2[3] / negative[3]
Further information: Pyuria
– 10 per µl or
mm3		 "Significant pyuria" at greater than or equal to 10 leucocytes per microlitre (µl) or cubic millimeter (mm3)
"Blood" /
(actually hemoglobin)		 n/a 0 / negative[3] dip-stick qualitative scale of 0 to 4+ Hemoglobinuria is suggestive of in vivo hemolysis. But needs to be distinguished from hematuria. In case of hemoglobinuria urine dipstick shows presence of blood but there are no RBC seen on microscopic examination. But if there is hematuria followed by artefactual ex vivo/in vitro hemolysis in the collected urine then also the dipstick test 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.

Other molecules [link]

Target Lower limit Upper limit Unit Comments
Glucose n/a 0 / negative[3] 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 that is filtered is normally reabsorbed from the renal tubules back into the blood. Presence of glucose in the urine is called glucosuria.
Further information: Glucosuria
Ketone bodies n/a 0 / negative[3] When there is 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 the disease diabetes mellitus, when a lack of the hormone insulin prevents the body cells from utilizing 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 utilized 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).
Further information: Ketonuria
Bilirubin n/a 0 / negative[3] 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 eye.
Further information: Bilirubinuria
Urobilinogen 0.2[3] 1.0 [3] Ehrlich units
or mg/dL
Creatinine – per day 4.8[4] 19[4] mmol / 24hours
Free catecholamines,
dopamine – per day		 90 [9] 420 [9] μg / 24hours
Free cortisol 28[10] or 30[11] 280[10] or 490[11] nmol/24h Values below threshold indicate Addison's disease, while values above indicate Cushing's syndrome. A value smaller than 200 nmol/24h (72 µg/24h[12]) strongly indicates absence of Cushing's syndrome.[11]
10[13] or 11[12] 100[13] or 176[12] µg/24h
Phenylalanine 30.0 mg/L[14] In neonatal screening, a value above upper limit defines phenylketonuria.[14]

Other urine parameters [link]

Test Lower limit Upper limit Unit Comments
Urine specific gravity 1.003 [1][3] 1.030[1][3] no unit 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 whether you are hydrated or dehydrated. If the SG of your urine is under 1.010 you are hydrated. If your urine SG is above 1.020, you are dehydrated.
Osmolality 400[4] n/a[4] mOsm/kg
pH 5[3] 7[3] (unitless)
Bacterial cultures by urination – 100,000 colony forming units per millilitre (CFU/mL) Bacteriuria can be confirmed if a single bacterial species is isolated in a concentration greater than 100,000 colony forming units per millilitre of urine in clean-catch midstream urine specimens (one for men, two consecutive specimens with the same bacterium for women).
Further information: Bacteriuria
by bladder catheterisation – 100 For urine collected via bladder catheterisation, the threshold is 100 colony forming units of a single species per millilitre.
Further information: Bacteriuria

Methods [link]

When a doctor orders a urinalysis they will request either a routine urinalysis or a R&M urinalysis. The difference being a routine urinalysis is everything but the microscopy or culture, whereas the R&M is Routine and Microscopy urinalysis.

Urine test strip [link]

A urine test strip can quantify parameters such as:

Microscopic examination [link]

A urine sample is about to be examined under a phase-contrast microscope using a Neubauer counting chamber. The urine is under the cover slide, in the upper segment formed by the H-shaped grooves.

The numbers and types of cells and/or material such as urinary casts can yield a great detail of information and may suggest a specific diagnosis.

Other methods of urinalysis [link]

See also [link]

References [link]

  1. ^ a b c Simerville JA, Maxted WC, Pahira JJ (March 2005). "Urinalysis: a comprehensive review". American Family Physician 71 (6): 1153–62. PMID 15791892. https://www.aafp.org/afp/20050315/1153.html. 
  2. ^ Harper, Douglas. "Urinalysis". Online Etymology Dictionary. https://www.etymonline.com/index.php?term=urinalysis&allowed_in_frame=0. Retrieved 26 September 2011. 
  3. ^ a b c d e f g h i j k l m n o p q r Normal Reference Range Table from The University of Texas Southwestern Medical Center at Dallas. Used in Interactive Case Study Companion to Pathologic basis of disease.
  4. ^ a b c d e f g h i j Reference range list from Uppsala University Hospital ("Laborationslista"). Artnr 40284 Sj74a. Issued on April 22, 2008
  5. ^ a b c d medscape.com > Urine Calcium: Laboratory Measurement and Clinical Utility By Kevin F. Foley, PhD, DABCC; Lorenzo Boccuzzi, DO. Posted: 12/26/2010; Laboratory Medicine. 2010;41(11):683–686. © 2010 American Society for Clinical Pathology. In turn citing:
    • Wu HBA. Tietz Guide to Clinical Laboratory Tests. 4th ed. St. Louis, MO: Saunders, Elsevier; 2006.
  6. ^ "MedlinePlus Medical Encyclopedia: Fractional excretion of sodium". https://www.nlm.nih.gov/medlineplus/ency/article/003602.htm. Retrieved 2009-05-02. 
  7. ^ Ajubi, N. E.; Nijholt, N.; Wolthuis, A. (2005). "Quantitative automated human chorionic gonadotropin measurement in urine using the Modular Analytics E170 module (Roche)". Clinical Chemistry and Laboratory Medicine 43 (1): 68–70. DOI:10.1515/CCLM.2005.010. PMID 15653445.  edit
  8. ^ a b "medical.history.interview: Lab Values". https://sitemaker.umich.edu/medical.history.interview/lab_values. Retrieved 2008-10-21. 
  9. ^ a b "University of Colorado Laboratory Reference Ranges". https://clinlab.uch.edu/asp/test_review/reference_ranges_all.asp. Retrieved 2008-10-21. 
  10. ^ a b Converted from µg/24h, using molar mass of 362.460 g/mol
  11. ^ a b c Görges, R.; Knappe, G.; Gerl, H.; Ventz, M.; Stahl, F. (1999). "Diagnosis of Cushing's syndrome: Re-evaluation of midnight plasma cortisol vs urinary free cortisol and low-dose dexamethasone suppression test in a large patient group". Journal of endocrinological investigation 22 (4): 241–249. PMID 10342356.  edit
  12. ^ a b c Converted from nmol/24h, using molar mass of 362.460 g/mol
  13. ^ a b MedlinePlus > Cortisol – urine. Update Date: 11/23/2009. Updated by: Ari S. Eckman. Also reviewed by David Zieve.
  14. ^ a b Kim, N. H.; Jeong, J. S.; Kwon, H. J.; Lee, Y. M.; Yoon, H. R.; Lee, K. R.; Hong, S. P. (2010). "Simultaneous diagnostic method for phenylketonuria and galactosemia from dried blood spots using high-performance liquid chromatography-pulsed amperometric detection". Journal of Chromatography B 878 (21): 1860–1864. DOI:10.1016/j.jchromb.2010.04.038. PMID 20494631.  edit

External links [link]

Wikimedia Commons has media related to: Urinalysis
Medical test: Reference range, Urine tests (CPT 81000–81099)
Protein
Small molecules
Blood cells
RBC · WBC
Chemical properties
Other
Abnormal clinical and laboratory findings for urine / Urine test / urination disorder (R80–R82, 791)
Red blood cells
White blood cells
Proteinuria
Small molecules
Pathogens
Other

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