Los análisis clínicos de orina son exámenes de las propiedades físicas y químicas de la orina y su apariencia microscópica para ayudar en el diagnóstico médico . [1] El término análisis de orina, una combinación de las palabras orina y análisis [2], generalmente se refiere al examen general de la orina, la evaluación química con tiras reactivas de orina y el examen microscópico . El examen de orina se centra en los parámetros que se pueden medir a simple vista (u otros sentidos), incluidos el volumen, el color, la transparencia, el olor y la gravedad específica ; Las tiras reactivas de orina miden propiedades químicas comopH , concentración de glucosa y niveles de proteínas ; y se realiza microscopía óptica para identificar elementos como células , cilindros urinarios , cristales y organismos . [3] : 441 Otros análisis que se realizan de forma rutinaria en muestras de orina incluyen niveles de electrolitos en la orina , pruebas de detección de drogas , pruebas de embarazo y cultivos microbiológicos .
Análisis de orina | |
---|---|
Especialidad | patologia clinica |
Malla | D016482 |
Otros códigos | Códigos LOINC para paneles de análisis de orina |
MedlinePlus | 003579 |
Métodos
Análisis de orina
El análisis de orina implica la evaluación de las propiedades físicas de la orina, como el color y la claridad; análisis químico con una tira reactiva de orina ; y examen microscópico. [3] : 441 El examen microscópico no siempre está incluido: puede reservarse para muestras que tienen resultados anormales en los exámenes preliminares o realizarse a solicitud del proveedor de atención médica. [4] Las tiras reactivas contienen almohadillas impregnadas con compuestos químicos que cambian de color cuando interactúan con elementos específicos en la orina; por ejemplo, nitrito , un compuesto producido por algunas bacterias que causan infecciones del tracto urinario , y esterasa leucocitaria , una enzima que se encuentra en los glóbulos blancos (WBC) que actúa como un indicador de la cantidad de WBC en la orina. La intensidad del cambio de color se correlaciona aproximadamente con la concentración de cada compuesto. [5] : 397–406
Si es necesaria la microscopía, primero se centrifuga la orina para concentrar los elementos sólidos para que puedan verse más fácilmente. Se coloca una gota de la muestra concentrada debajo de un cubreobjetos y se examina, generalmente con un aumento de 10x y 40x . [5] : 414–5 Si es necesario determinar el número exacto de células o cilindros en la muestra, se puede colocar en una cámara de recuento llamada hemocitómetro . [3] : 461 La orina se examina tradicionalmente mediante microscopía óptica , pero algunos laboratorios utilizan microscopios de contraste de fase , que mejoran la visualización de elementos como los cilindros urinarios y el moco. [5] : 414–5 También existen sistemas automatizados que utilizan tecnología de citometría de flujo con sensor de flujo y otros con reconocimiento de patrones para identificar elementos microscópicos en la orina. [6]
Tira reactiva de orina
Una tira reactiva de orina puede cuantificar:
- Leucocitos : con presencia en la orina conocida como leucocituria
- Nitrito : con presencia en la orina conocida como nitrituria
- Proteína : con presencia en la orina conocida como proteinuria , albuminuria o microalbuminuria
- Eritrocitos : con presencia en la orina conocida como hematuria.
- Gravedad específica
- Glucosa : con presencia en la orina conocida como glucosuria.
- Bilirrubina : con presencia en la orina conocida como bilirrubinuria.
- Cetonas : con presencia en la orina conocida como cetonuria
Examinación microscópica
La cantidad y los tipos de células y / o material, como los cilindros urinarios, pueden proporcionar una gran cantidad de información detallada y pueden sugerir un diagnóstico específico.
- Hematuria : asociada con cálculos renales , infecciones , tumores y otras afecciones.
- Piuria : asociada con infecciones urinarias
- Eosinofiluria : asociada con nefritis intersticial alérgica , enfermedad ateroembólica
- Cilindros de glóbulos rojos : asociados con glomerulonefritis , vasculitis o hipertensión maligna
- Cilindros de glóbulos blancos : asociados con nefritis intersticial aguda , glomerulonefritis exudativa o pielonefritis grave
- (Hem) cilindros granulares - asociados con necrosis tubular aguda
- Cristaluria : asociada con nefropatía aguda por uratos (o nefropatía aguda por ácido úrico, AUAN)
- Oxalatino de calcio : asociado con etilenglicol , enfermedad de cálculos renales
- Moldes céreos : asociados con enfermedad renal crónica
Otros metodos
- Cultivo de orina: un cultivo microbiológico de muestras de orina, que detecta bacteriuria , está indicado cuando se sospecha una infección del tracto urinario .
- Ictotest: esta prueba se utiliza para detectar la destrucción de glóbulos rojos viejos en la orina.
- Prueba de hemoglobina : esta prueba para detectar hemólisis en los vasos sanguíneos, una ruptura en los capilares del glomérulo o hemorragia en el sistema urinario, lo que hace que la hemoglobina aparezca en la orina.
Parámetros de destino
Los resultados de las pruebas de orina siempre deben interpretarse utilizando el rango de referencia proporcionado por el laboratorio que realizó la prueba o utilizando la información proporcionada por el fabricante de la tira reactiva / dispositivo. [7] [8]
Color
Los siguientes son ejemplos de algunos colores de orina y sus causas (no es una lista completa).
- Casi incoloro: ingesta excesiva de líquidos para las afecciones; diabetes mellitus no tratada , diabetes insípida y ciertos tipos de nefritis .
- Amarillo: la orina claramente amarilla puede indicar una ingesta excesiva de riboflavina (vitamina B 2 ).
- Amarillo-ámbar: Normal.
- Amarillo-turbio: cristales excesivos ( cristaluria ) y / o pus excesivo ( piuria ).
- Naranja: Ingesta de líquido insuficiente para las condiciones; ingesta de sustancias naranjas; ingesta de fenazopiridina para los síntomas urinarios.
- Rojo: fuga de glóbulos rojos o de hemoglobina de dichas células; hemólisis; ingesta de sustancias rojas.
- Oscuro:
- Naranja rojizo: ingesta de ciertos medicamentos u otras sustancias.
- Amarillo oxidado a marrón rojizo: ingesta de ciertos medicamentos u otras sustancias.
- Marrón oscuro: ingesta de ciertos medicamentos u otras sustancias; músculo dañado ( mioglobinuria debido a rabdomiólisis ) por ejercicio extremo u otro daño generalizado, posiblemente relacionado con medicamentos; sangre alterada; bilirrubinuria ; ingesta de sustancias fenólicas ; metabolismo inadecuado de las porfirinas ; melanina de tumores melanocíticos ; presencia de una forma anormal de hemoglobina, metahemoglobina.
- Negro pardusco a negro: ingesta de sustancias o medicamentos; sangre alterada; un problema con el metabolismo del ácido homogentísico ( alcaptonuria ), que también puede causar el blanco oscuro de los ojos y los órganos y tejidos internos de color oscuro ( ocronosis ); Intoxicación con Lysol (un producto que contiene fenoles ); melanina de tumores melanocíticos ). La parafenilendiamina es un ingrediente altamente tóxico de las formulaciones de tintes para el cabello que puede causar una lesión renal aguda y dar como resultado una orina negra. [9]
- Morado debido al síndrome de la bolsa de orina morada . [9]
- De magenta a rojo púrpura: Presencia de fenolftaleína , un laxante estimulante que se encontraba anteriormente en Ex-Lax. [10]
- Green, or dark with a greenish hue: Jaundice (bilirubinuria); problem with bile metabolism. Recent surgery requiring high doses of propofol infusion.[9] The use of a medication (Uribel) that is similar to phenazopyridine for the relief of urinary symptoms.
- Other colors: Various substances ingested in food or drink, particularly up to 48 hours prior to the presence of colored urine.[11]
Smell
The odor (scent) of urine can normally vary from odorless (when very light colored and dilute) to a much stronger odor when the subject is dehydrated and the urine is concentrated. Brief changes in odor are usually merely interesting and not medically significant. (Example: the abnormal smell many people can detect after eating asparagus.) The urine of diabetics experiencing ketoacidosis (urine containing high levels of ketone bodies) may have a fruity or sweet smell.[12]
Ions and trace minerals
Target | Lower limit | Upper limit | Unit | Comments | LOINC Codes |
---|---|---|---|---|---|
Nitrite | n/a | The presence of nitrites in urine, termed nitrituria, indicates the presence of coliform bacteria. | |||
Sodium (Na) – per day | 150[14] | 300[14] | mmol / 24 h | A urinalysis is frequently ordered during the workup of acute kidney injury. Full kidney function can be detected through the simple dipstick method. | 2956-1 |
Potassium (K) – per day | 40[14] | 90[14] | 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[15] | 20[15] | mmol / 24 h | An abnormally high level is called hypercalciuria and an abnormally low rate is called hypocalciuria. | 14637-3 |
100[15] | 250[15] | mg / 24 hours | 6874-2 | ||
Phosphate (P) – per day | n/a[14] | 38[14] | mmol / 24 h | Phosphaturia is the hyperexcretion of phosphate in the urine. This condition is divided into primary and secondary types. Primary hyperphosphaturia is characterized by direct excess excretion of phosphate by the kidneys, as from primary kidney 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 kidney failure and oliguria, with a value below 1% indicating a prerenal disease and a value above 3%[16] indicating acute tubular necrosis or other kidney damage.
Proteins and enzymes
Target | Lower limit | Upper limit | Unit | Comments |
---|---|---|---|---|
Protein | 0 | trace amounts[13] / 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 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[17] | U/l | This hormone appears in the urine of pregnant women. It also appears in cases of testicular cancer in men. Home pregnancy tests commonly detect this substance. |
Blood cells
Target | Lower limit | Upper limit | Unit | Comments |
---|---|---|---|---|
Red blood cells (RBCs) / erythrocytes | 0[13][18] | 2[13] – 3[18] | per High Power Field (HPF) | May be present as intact RBCs, which indicate bleeding. Even a trace amount of blood is enough to give the entire urine sample a red/pink hue, with difficulty in judging 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 artifact 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 dysmorphic features appear. The dysmorphic RBCs in urine most characteristic of glomerular origin are called "G1 cells", 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[13] | ||
White blood cells (WBCs) / leukocytes / (pus cells) | 0[13] | 2[13] / negative[13] | ||
– | 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[13] | 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. |
Other molecules
Target | Lower limit | Upper limit | Unit | Comments |
---|---|---|---|---|
Glucose | n/a | 0 / negative[13] | 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[13] | 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[13] | 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. | |
Urobilinogen | 0.2[13] | 1.0[13] | Ehrlich units or mg/dL | |
Creatinine | 4.8[14] | 19[14] | mmol / 24 h | |
Urea | 12 | 20 | g / 24 h | |
Uric acid | 250 | 750 | mg / 24 h | |
Free catecholamines, dopamine – per day | 90[19] | 420[19] | μg / 24 hours | |
Free cortisol | 28[20] or 30[21] | 280[20] or 490[21] | 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[22]) strongly indicates absence of Cushing's syndrome.[21] |
10[23] or 11[22] | 100[23] or 176[22] | µg/24 h | ||
Phenylalanine | 30.0 | mg/L[24] | In neonatal screening, a value above the upper limit defines phenylketonuria.[24] |
Other urine parameters
Test | Lower limit | Upper limit | Unit | Comments | |
---|---|---|---|---|---|
Urine specific gravity | 1.003[25][13] | 1.030[25][13] | 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[14] | n/a[14] | mOsm/kg | Urine osmolality testing can be used in conjunction with Plasma osmolality tests to confirm diagnosis of SIADH[26] | |
pH | 5[13] | 7[13] | (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 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. |
Drugs
Urine may be tested to determine whether an individual has engaged in recreational drug use. In this case, the urinalysis would be designed to detect whatever marker indicates drug use.
Historia
Helen Murray Free and her husband, Alfred Free, pioneered dry reagent urinalysis, resulting in the 1956 development of Clinistix (also known as Clinistrip), the first dip-and-read test for glucose in urine for patients with diabetes.[27] This breakthrough led to additional dip-and-read tests for proteins and other substances.[28] The invention was named a National Historic Chemical Landmark by the American Chemical Society in May 2010.[29]
Ver también
- Uroscopy, the ancient form of this analysis
- Urinary casts
- Proteinuria
- Urine test strip
- Urine collection device
- Pregnancy test, measures hCG levels in urine
Referencias
- ^ Roxe, DM (1990), "A5417", Urinalysis (3rd ed.), Boston: Butterworths, PMID 21250145
- ^ Harper, Douglas. "Urinalysis". Online Etymology Dictionary. Archived from the original on 21 August 2012. Retrieved 26 September 2011.
- ^ a b c McPherson, RA; Pincus, MR (2017). Henry's Clinical Diagnosis and Management by Laboratory Methods (23 ed.). Elsevier Health Sciences. ISBN 978-0-323-41315-2.
- ^ "Urinalysis". Lab Tests Online. 27 Jan 2021. Retrieved 15 Feb 2021.
- ^ a b c Turgeon, ML (2016). Linné & Ringsrud's Clinical Laboratory Science: Concepts, Procedures, and Clinical Applications (7 ed.). Elsevier Mosby. ISBN 978-0-323-22545-8.
- ^ Oyaert, Matthijs; Delanghe, Joris (2019). "Progress in Automated Urinalysis". Annals of Laboratory Medicine. 39 (1): 15–22. doi:10.3343/alm.2019.39.1.15. ISSN 2234-3806.
- ^ "Reference Ranges and What They Mean". Lab Tests Online (USA). Archived from the original on 28 August 2013. Retrieved 22 June 2013.
- ^ "Urine Drug Test". Archived from the original on 2018-12-07. Retrieved 2018-11-25. Sunday, 25 November 2018
- ^ a b c https://reference.medscape.com/slideshow/discolored-urine-6008332?src=wnl_critimg_171117_mscpref_v2&uac=20524DV&impID=1486503&faf=1#18 Archived 2018-04-30 at the Wayback Machine Medscape, 12 Causes of Discolored Urine.
- ^ Murphy, James (6 May 2009). "Movement Away From Phenolphthalein in Laxatives". JAMA. 301 (17): 1770. doi:10.1001/jama.2009.585. PMID 19417193.
- ^ "Urine color - Symptoms and causes". mayoclinic.org. Archived from the original on 14 September 2017. Retrieved 30 April 2018.
- ^ "Urine odor Causes". mayoclinic.org. Archived from the original on 9 January 2018. Retrieved 30 April 2018.
- ^ a b c d e f g h i j k l m n o p q r Normal Reference Range Table Archived December 25, 2011, at the Wayback Machine from The University of Texas Southwestern Medical Center at Dallas. Used in Interactive Case Study Companion to Pathologic basis of disease.
- ^ 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
- ^ a b c d medscape.com - Urine Calcium: Laboratory Measurement and Clinical Utility Archived 2011-09-06 at the Wayback Machine 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.
- ^ "MedlinePlus Medical Encyclopedia: Fractional excretion of sodium". Archived from the original on 2009-05-03. Retrieved 2009-05-02.
- ^ Ajubi NE, 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. S2CID 42575043.
- ^ a b "medical.history.interview: Lab Values". Archived from the original on 2012-12-12. Retrieved 2008-10-21.
- ^ a b "University of Colorado Laboratory Reference Ranges". Archived from the original on 2008-05-07. Retrieved 2008-10-21.
- ^ a b Converted from µg/24 h, using molar mass of 362.460 g/mol
- ^ 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. doi:10.1007/bf03343551. PMID 10342356. S2CID 1239611.
- ^ a b c Converted from nmol/24h, using molar mass of 362.460 g/mol
- ^ a b MedlinePlus - Cortisol – urine Archived 2016-05-29 at the Wayback Machine. Update Date: 11/23/2009. Updated by: Ari S. Eckman. Also reviewed by David Zieve.
- ^ a b Kim NH, Jeong JS, Kwon HJ, Lee YM, Yoon HR, Lee KR, Hong SP (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.
- ^ a b Simerville JA, Maxted WC, Pahira JJ (March 2005). "Urinalysis: a comprehensive review". American Family Physician. 71 (6): 1153–62. PMID 15791892. Archived from the original on 2005-06-02.
- ^ William C. Wilson; Christopher M. Grande; David B. Hoyt (2007-02-05). Trauma: Critical Care. CRC Press. pp. 179–. ISBN 978-1-4200-1684-0.
- ^ "Helen M. Free". American Chemical Society. Archived from the original on 13 November 2016. Retrieved 13 November 2016.
- ^ "The Development of Diagnostic Test Strips" (PDF). American Chemical Society. Archived (PDF) from the original on 7 February 2017. Retrieved 13 November 2016.
- ^ "Al and Helen Free and the development of diagnostic test strips". American Chemical Society. Archived from the original on 13 November 2016. Retrieved 13 November 2016.
enlaces externos
- Conoximent de las Orines, an early book about analyzing urine for medical purposes. Estimated date 1466.