Medical test

Short description: Medical procedure

For sociological tests, see Laboratory studies. For laboratory test, see Blood test.

"Medical investigation" redirects here. For the television series, see Medical Investigation.

Medical test

X-ray of a hand. X-rays are a common medical test.

MeSH| D019937

[edit on Wikidata]

A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, diagnostic imaging, genetic testing, chemical and cellular analysis, relating to clinical chemistry and molecular diagnostics, are typically performed in a medical setting.

## Contents

* 1 Types of tests
* 1.1 By purpose
* 1.1.1 Diagnostic
* 1.1.2 Screening
* 1.1.3 Monitoring
* 1.2 By method
* 1.3 By sample location
* 2 Accuracy and precision
* 3 Detection and quantification
* 3.1 Positive or negative
* 3.2 Continuous values
* 4 Interpretation
* 5 Risks
* 6 Indications
* 7 Patient expectations
* 8 Standard for the reporting and assessment
* 9 List of medical tests
* 10 See also
* 11 References
* 12 Further reading

## Types of tests

### By purpose

Medical tests can be classified by their purposes, including diagnosis, screening or monitoring.

#### Diagnostic

Lung scintigraphy evaluating lung cancer

A diagnostic test is a procedure performed to confirm or determine the presence of disease in an individual suspected of having a disease, usually following the report of symptoms, or based on other medical test results.[1][2] This includes posthumous diagnosis. Examples of such tests are:

* Using nuclear medicine to examine a patient suspected of having a lymphoma.
* Measuring the blood sugar in a person suspected of having diabetes mellitus after periods of increased urination.
* Taking a complete blood count of an individual experiencing a high fever to check for a bacterial infection.[1]
* Monitoring electrocardiogram readings on a patient with chest pain to diagnose or determine any heart irregularities.[3]

#### Screening

Screening refers to a medical test or series of tests used to detect or predict the presence of disease in at-risk individuals within a defined group such as a population, family, or workforce.[4][5] Screenings may be performed to monitor disease prevalence, manage epidemiology, aid in prevention, or strictly for statistical purposes.[6]

Examples of screenings include measuring the level of TSH in the blood of a newborn infant as part of newborn screening for congenital hypothyroidism,[7] checking for Lung cancer in non-smoking individuals who are exposed to second-hand smoke in an unregulated working environment, and Pap smear screening for prevention or early detection of cervical cancer.

#### Monitoring

Some medical tests are used to monitor the progress of, or response to medical treatment.

### By method

Most test methods can be classified into one of the following broad groups:

* Patient observations, which may be photographed or recorded
* Questions asked when taking an individual's medical history
* Tests performed in a physical examination
* Radiologic tests, in which, for example, x-rays are used to form an image of a body target. These tests often involve administration of a contrast agent.
* In vivo diagnostics which test in the body, such as:
* Manometry[8]
* Administering a diagnostic agent and measuring the body's response, as in the gluten challenge test, contraction stress test, bronchial challenge test, oral food challenge, or the ACTH stimulation test.
* In vitro diagnostics which test a sample of tissue or bodily fluids,[9][10] such as:
* Liquid biopsy
* Microbiological culturing, which determines the presence or absence of microbes in a sample from the body, and usually targeted at detecting pathogenic bacteria.
* Genetic testing
* Blood sugar level[11]
* Liver function testing[12]
* Calcium testing[12]
* Testing for electrolytes in the blood, such as sodium, potassium, creatinine, and urea[13]

### By sample location

In vitro tests can be classified according to the location of the sample being tested, including:

* Blood tests
* Urine tests, including naked eye exam of the urine
* Stool tests, including naked eye exam of the feces
* Sputum (phlegm), including naked eye exam of the sputum

## Accuracy and precision

Main article: Accuracy and precision

* Accuracy of a laboratory test is its correspondence with the true value. Accuracy is maximized by calibrating laboratory equipment with reference material and by participating in external quality control programs.
* Precision of a test is its reproducibility when it is repeated on the same sample. An imprecise test yields widely varying results on repeated measurement. Precision is monitored in laboratory by using control material.

## Detection and quantification

### Positive or negative

The classification of tests into either positive or negative results in a binary classification, allowing for the application of bayesian probability and the calculation of diagnostic test accuracy measures, such as sensitivity, specificity, likelihood ratios, and the diagnostic odds ratio.[14][15] These metrics are commonly used in systematic review of diagnostic test accuracy and meta-analyses of diagnostic accuracy studies.[16]

### Continuous values

Tests whose results are of continuous values, such as most blood values, can be interpreted as they are, or they can be converted to a binary ones by defining a cutoff value, with test results being designated as positive or negative depending on whether the resultant value is higher or lower than the cutoff.

## Interpretation

In the finding of a pathognomonic sign or symptom it is almost certain that the target condition is present, and in the absence of finding a sine qua non sign or symptom it is almost certain that the target condition is absent. In reality, however, the subjective probability of the presence of a condition is never exactly 100% or 0%, so tests are rather aimed at estimating a post-test probability of a condition or other entity.

Most diagnostic tests basically use a reference group to establish performance data such as predictive values, likelihood ratios and relative risks, which are then used to interpret the post-test probability for an individual.

In monitoring tests of an individual, the test results from previous tests on that individual may be used as a reference to interpret subsequent tests.

## Risks

Some medical testing procedures have associated health risks, and even require general anesthesia, such as the mediastinoscopy.[17] Other tests, such as the blood test or pap smear have little to no direct risks.[18] Medical tests may also have indirect risks, such as the stress of testing, and riskier tests may be required as follow-up for a (potentially) false positive test result. Consult the health care provider (including physicians, physician assistants, and nurse practitioners) prescribing any test for further information.

## Indications

Each test has its own indications and contraindications. An indication is a valid medical reason to perform the test. A contraindication is a valid medical reason not to perform the test. For example, a basic cholesterol test may be indicated (medically appropriate) for a middle-aged person. However, if the same test was performed on that person very recently, then the existence of the previous test is a contraindication for the test (a medically valid reason to not perform it).

Information bias is the cognitive bias that causes healthcare providers to order tests that produce information that they do not realistically expect or intend to use for the purpose of making a medical decision. Medical tests are indicated when the information they produce will be used. For example, a screening mammogram is not indicated (not medically appropriate) for a woman who is dying, because even if breast cancer is found, she will die before any cancer treatment could begin.

In a simplified fashion, how much a test is indicated for an individual depends largely on its net benefit for that individual. Tests are chosen when the expected benefit is greater than the expected harm. The net benefit may roughly be estimated by:[19]

bn=Δp×ri×(bi−hi)−ht

, where:

* bn is the net benefit of performing a test
* Λp is the absolute difference between pre- and posttest probability of conditions (such as diseases) that the test is expected to achieve. A major factor for such an absolute difference is the power of the test itself, such as can be described in terms of, for example, sensitivity and specificity or likelihood ratio. Another factor is the pre-test probability, with a lower pre-test probability resulting in a lower absolute difference, with the consequence that even very powerful tests achieve a low absolute difference for very unlikely conditions in an individual (such as rare diseases in the absence of any other indicating sign), but on the other hand, that even tests with low power can make a great difference for highly suspected conditions. The probabilities in this sense may also need to be considered in context of conditions that are not primary targets of the test, such as profile-relative probabilities in a differential diagnostic procedure.
* ri is the rate of how much probability differences are expected to result in changes in interventions (such as a change from "no treatment" to "administration of low-dose medical treatment"). For example, if the only expected effect of a medical test is to make one disease more likely compared to another, but the two diseases have the same treatment (or neither can be treated), then, this factor is very low and the test is probably without value for the individual in this aspect.
* bi is the benefit of changes in interventions for the individual
* hi is the harm of changes in interventions for the individual, such as side effects of medical treatment
* ht is the harm caused by the test itself.

Some additional factors that influence a decision whether a medical test should be performed or not included: cost of the test, availability of additional tests, potential interference with subsequent test (such as an abdominal palpation potentially inducing intestinal activity whose sounds interfere with a subsequent abdominal auscultation), time taken for the test or other practical or administrative aspects. The possible benefits of a diagnostic test may also be weighed against the costs of unnecessary tests and resulting unnecessary follow-up and possibly even unnecessary treatment of incidental findings.[20]

In some cases, tests being performed are expected to have no benefit for the individual being tested. Instead, the results may be useful for the establishment of statistics in order to improve health care for other individuals. Patients may give informed consent to undergo medical tests that will benefit other people.

## Patient expectations

In addition to considerations of the nature of medical testing noted above, other realities can lead to misconceptions and unjustified expectations among patients. These include: Different labs have different normal reference ranges; slightly different values will result from repeating a test; "normal" is defined by a spectrum along a bell curve resulting from the testing of a population, not by "rational, science-based, physiological principles"; sometimes tests are used in the hope of turning something up to give the doctor a clue as to the nature of a given condition; and imaging tests are subject to fallible human interpretation and can show "incidentalomas", most of which "are benign, will never cause symptoms, and do not require further evaluation," although clinicians are developing guidelines for deciding when to pursue diagnoses of incidentalomas.[21]

## Standard for the reporting and assessment

The QUADAS-2 revision is available.[22]

## List of medical tests

## See also

* Blood culture
* Chemical test
* Gold standard (test)
* Medical sign
* Molecular diagnostics
* Nailbed assessment
* Test panel
* Point-of-care testing
* EU IVD Regulation

## References

1. ↑ 1.0 1.1 "The diagnostic value of absolute neutrophil count, band count and morphological changes of neutrophils in predicting bacterial infections". Med Princ Pract 16 (5): 344–347. 2007. doi:10.1159/000104806. PMID 17709921.
2. ↑ Harvard.edu
Guide to Diagnostic Tests from Harvard Health
3. ↑ "Harvard.edu". http://www.health.harvard.edu/a_to_z/electrocardiogram-ekg.
4. ↑ "The prevalence of screening: a report from the National Institute of Occupational Safety and the Health National Occupational Hazard Survey". Journal of Occupational Medicine 28 (10): 906–912. 1986. doi:10.1097/00043764-198610000-00003. PMID 3021937. https://zenodo.org/record/1234830. Retrieved 2019-09-16.
5. ↑ Osha.gov
US Dept. of Labor – Occupational Safety and Health Admin.
6. ↑ "Medical Screening and Biological Monitoring: A guide to the literature for physicians". Journal of Occupational and Environmental Medicine 37 (2): 170–184. 1995. doi:10.1097/00043764-199502000-00016. PMID 7655958. https://zenodo.org/record/1234834. Retrieved 2020-09-08.
7. ↑ "Congenital hypothyroidism and mental development". Comprehensive Therapy 20 (6): 342–346. 1994. PMID 8062543.
8. ↑ OSA | Design of a high-sensor count fibre optic manometry catheter for in-vivo colonic diagnostics
9. ↑ "Directive 98/79/CE on in vitro diagnostic medical devices". http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:1998:331:0001:0037:EN:PDF.
10. ↑ "In Vitro Diagnostic (IVD) tests". http://www.edma-ivd.be/index.php?id=6.
11. ↑ "Glucose Tests". 14 November 2019. http://www.labtestsonline.org.uk/understanding/analytes/glucose/tab/test.
12. ↑ 12.0 12.1 "Liver Function Tests". 10 January 2020. http://www.labtestsonline.org.uk/understanding/analytes/liver-panel/.
13. ↑ "Electrolytes and Anion Gap". 9 October 2019. http://www.labtestsonline.org.uk/understanding/analytes/lytes.
14. ↑ Altman DG, Bland JM. Diagnostic tests 1: sensitivity and specificity. BMJ. 1994;308(6943):1552.
15. ↑ Deeks JJ, Altman DG. Diagnostic tests 4: likelihood ratios. BMJ. 2004;329:168.
16. ↑ "Handbook for DTA Reviews". Cochrane. https://methods.cochrane.org/sdt/handbook-dta-reviews.
17. ↑ "Mediastinoscopy". Harvard.edu. October 2016. http://www.health.harvard.edu/diagnostic-tests/mediastinoscopy.htm.
18. ↑ Diagnostic Tests > Pap Smear, Harvard University, http://www.health.harvard.edu/diagnostic-tests/pap-smear.htm
19. ↑ Mikael Häggström, M.D.. "Clinical pathology". https://patholines.org/Clinical_pathology. Retrieved 2024-02-15.
20. ↑ "Rapid magnetic resonance imaging vs radiographs for patients with low back pain: a randomized controlled trial". JAMA 289 (21): 2810–8. 2003. doi:10.1001/jama.289.21.2810. PMID 12783911.
21. ↑ Hall, Harriet (2019). "Too Many Medical Tests". Skeptical Inquirer 43 (3): 25–27.
22. ↑ "QUADAS-2: a revised tool for the quality assessment of diagnostic accuracy studies". Annals of Internal Medicine 155 (8): 529–36. October 2011. doi:10.7326/0003-4819-155-8-201110180-00009. PMID 22007046.

## Further reading

* First WHO Model List of Essential In Vitro Diagnostics. Geneva: World Health Organization. 2019. WHO Technical Report Series, No. 1017. License: CC BY-NC-SA 3.0 IGO. ISBN 978-92-4-121026-3.

* v
* t
* e

Medical imaging (ICD-9-CM V3 87–88, ICD-10-PCS B, CPT 70010–79999)

X-ray/
Radiography|

| 2D|

| Medical:|

* Pneumoencephalography
* Dental radiography
* Sialography
* Myelography
* CXR
* Bronchography
* AXR
* KUB
* DXA/DXR
* Upper gastrointestinal series/Small-bowel follow-through/Lower gastrointestinal series
* Cholangiography/Cholecystography
* Mammography
* Pyelogram
* Cystography
* Arthrogram
* Hysterosalpingography
* Skeletal survey
* Angiography
* Angiocardiography
* Aortography
* Venography
* Lymphogram
* Orbital radiography

|

Industrial:|

* Radiographic testing

CT scan|

| Techniques:|

* General operation of CT
* Quantitative CT
* High-resolution CT
* X-ray microtomography
* Electron beam computed tomography
* Cone beam computed tomography

|

Targets|

* Coronary
* Calcium scan
* CT angiography
* Abdominal and pelvic CT
* Virtual colonoscopy
* CT angiography
* Coronary CT
* Pulmonary CT
* Head CT
* Thyroid CT
* Whole body imaging
* Full-body CT scan

Other|

* Fluoroscopy
* Dental panoramic radiography
* X-ray motion analysis

MRI|

* MRI of the brain
* MR neurography
* Cardiac MRI/Cardiac MRI perfusion
* MR angiography
* MR cholangiopancreatography
* Breast MRI
* Functional MRI
* Sequences
* Diffusion MRI
* Perfusion MRI
* Tractography
* Synthetic MRI

Ultrasound|

* Echocardiography
* Doppler ultrasonography
* Doppler echocardiography
* TTE
* TEE
* Transcranial Doppler
* Intravascular
* Gynecologic
* Obstetric
* Echoencephalography
* Abdominal ultrasonography
* Transrectal
* Breast ultrasound
* Transscrotal ultrasound
* Carotid ultrasonography
* Contrast-enhanced
* 3D ultrasound
* Endoscopic ultrasound
* Emergency ultrasound
* FAST
* Pre-hospital ultrasound
* Duplex

Radionuclide|

| 2D / scintigraphy|

* Cholescintigraphy
* Scintimammography
* Ventilation/perfusion scan
* Radionuclide ventriculography
* Radionuclide angiography
* Radioisotope renography
* Sestamibi parathyroid scintigraphy
* Radioactive iodine uptake test
* Bone scintigraphy
* Immunoscintigraphy
* Dacryoscintigraphy
* DMSA scan
* Gastric emptying scan

Full body:|

* Octreotide scan
* Gallium 67 scan
* Indium-111 WBC scan

3D / ECT|

| SPECT (gamma ray):|

* Myocardial perfusion imaging

|

PET (positron):|

* Brain PET
* Cardiac PET
* PET mammography
* PET-CT
* PET-MRI

Optical/Laser|

* Optical tomography
* Optical coherence tomography
* Confocal microscopy
* Endomicroscopy
* Orthogonal polarization spectral imaging

Thermography|

* non-contact thermography
* contact thermography
* dynamic angiothermography

Target conditions|

* Acute stroke
* Pregnancy

* Category

Template:Urine tests

* v
* t
* e

Common for blood tests (CPT 82000–84999)

Electrolytes|

* Sodium
* Potassium
* Chloride
* Calcium
* Renal function
* Creatinine
* Urea
* BUN-to-creatinine ratio
* Plasma osmolality
* Serum osmolal gap

Acid-base|

* Anion gap
* Arterial blood gas
* Base excess
* Bicarbonate
* CO2 content

Iron tests|

* Ferritin
* Serum iron
* Transferrin saturation
* Total iron-binding capacity
* Transferrin
* Transferrin receptor

Hormones|

* ACTH stimulation test
* Thyroid function tests
* Thyroid-stimulating hormone

Metabolism|

* Blood lipids

Cardiovascular|

* Cardiac marker
* Troponin test
* CPK-MB test
* Lactate dehydrogenase
* Myoglobin
* Glycogen phosphorylase isoenzyme BB

Liver function tests|

* Proteins
* Human serum albumin
* Serum total protein
* ALP
* transaminases
* ALT
* AST
* AST/ALT ratio
* Bilirubin
* Unconjugated
* Conjugated

Pancreas|

* Amylase
* Lipase
* Pancreatic lipase

* v
* t
* e

Myeloid blood tests (CPT 85002–85999)

Clotting|

* CBC
* Platelet count
* Mean platelet volume
* vWF:
* Ristocetin-induced platelet aggregation

clotting factors:|

* Prothrombin time
* Partial thromboplastin time
* Thrombin time
* Activated clotting time

other/general:|

* coagulation
* Bleeding time
* animal enzyme
* Reptilase time
* Ecarin clotting time
* Dilute Russell's viper venom time
* Thromboelastography
* Thrombodynamics test

fibrinolysis:|

* Euglobulin lysis time
* D-dimer

Red blood cell indices|

| CBC|

* RBC count
* Hematocrit
* Hemoglobin

|

ratios:|

* Mean corpuscular hemoglobin
* Mean corpuscular hemoglobin concentration
* Mean corpuscular volume
* Red blood cell distribution width

Fetal hemoglobin:|

* Apt–Downey test
* Kleihauer–Betke test

Other|

* Reticulocyte index
* Haptoglobin
* Mentzer index

CFU-GM|

* Nitro blue tetrazolium chloride test
* Complete blood count
* White blood cell differential
* Absolute neutrophil count

Other|

* Blood film
* Leucoerythroblastic
* Blood viscosity
* Erythrocyte sedimentation rate

* v
* t
* e

Medical tests on Cerebrospinal fluid (CPT 82000-84999)

Albumin|

* CSF albumin
* CSF/serum albumin ratio

Glucose|

* CSF glucose
* CSF/serum glucose ratio

Other|

* Baricity

* v
* t
* e

Medical tests used in immunology and for inflammation (CPT 86000–86849)

Immunology|

| Immunoprecipitation|

* Chromatin immunoprecipitation
* Immunodiffusion
* Ouchterlony double immunodiffusion
* Radial immunodiffusion
* Immunoelectrophoresis
* Counterimmunoelectrophoresis

|

Immunoassay|

* ELISA
* ELISpot
* Enzyme Multiplied Immunoassay Technique
* RAST test
* Radioimmunoassay
* Radiobinding assay
* Immunofluorescence

Agglutination|

* [[Medicine:HemagglutiHemagglutination]]/Hemagglutinin
* Coombs test
* Latex fixation test

Other|

* Diagnostic immunology
* Nephelometry
* Complement fixation test
* Immunocytochemistry
* Immunohistochemistry
* Direct fluorescent antibody
* Epitope mapping
* Skin allergy test
* Patch test
* see also...

Inflammation|

* C-reactive protein
* Procalcitonin

* Total complement activity
* MELISA

* Complete blood count
* lymphocyte count

* v
* t
* e

Transfusion medicine

General concepts|

* Apheresis (plasmapheresis, plateletpheresis, leukapheresis)
* Blood transfusion
* Blood typing
* Coombs test (direct and indirect)
* Cross-matching
* Exchange transfusion
* International Society of Blood Transfusion
* Intraoperative blood salvage
* ISBT 128
* Transfusion reactions

Blood group systems /
blood types|

* ABO
* Secretor status
* Chido-Rodgers
* Colton
* Cromer
* Diego
* Dombrock
* Duffy
* Er
* FORS
* Gerbich
* GIL
* GLOB
* Hh
* Ii
* Indian
* JR
* JMH
* Kell (Xk)
* Kidd
* Knops
* Lan
* Lewis
* Lutheran
* LW
* MNS
* OK
* P
* Raph
* Rh and RHAG
* Scianna
* T-Tn
* Vel
* Xg
* Yt
* Other

Blood products /
blood donation|

* Whole blood
* Platelets
* Red blood cells
* Plasma / Fresh frozen plasma / PF24 (Cryoprecipitate \+ Cryosupernatant)
* Blood substitutes

Template:Infectious blood tests

* v
* t
* e

Pathology

Principles of pathology|

* Disease
* Infection
* Neoplasia
* Cause
* Pathogenesis
* Hemodynamics
* Ischemia
* Inflammation
* Cell damage
* Wound healing

Cellular adaptation

Atrophy
Hypertrophy
Hyperplasia
Dysplasia
Metaplasia

Squamous
Glandular

Cell death

Necrosis

Coagulative necrosis
Liquefactive necrosis
Gangrenous necrosis
Caseous necrosis
Fat necrosis
Fibrinoid necrosis
Myocytolysis
Programmed cell death

Apoptosis
Pyknosis
Karyorrhexis
Karyolysis

Accumulations
pigment

Hemosiderin
Lipochrome/Lipofuscin
Melanin
Steatosis

Anatomical pathology|

* Surgical pathology
* Cytopathology
* Autopsy
* Molecular pathology
* Forensic pathology
* Oral and maxillofacial pathology

* Gross examination
* Histopathology
* Immunohistochemistry
* Electron microscopy
* Immunofluorescence
* Fluorescence in situ hybridization

Clinical pathology|

* Clinical chemistry
* Hematopathology
* Transfusion medicine
* Medical microbiology
* Diagnostic immunology
* Immunopathology

* Enzyme assay
* Mass spectrometry
* Chromatography
* Flow cytometry
* Blood bank
* Microbiological culture
* Serology

* v
* t
* e

Medical test: Electrodiagnosis

Heart|

* Electrocardiography
* Vectorcardiography
* Magnetocardiography

Central nervous system|

* Electroencephalography (Intracranial EEG, stereoelectroencephalography)
* Magnetoencephalography

Peripheral nervous system|

* Electromyography (Facial electromyography)
* Nerve conduction study

Ears|

* Electrocochleography

Eyes|

* Electronystagmography
* Electrooculography
* Electroretinography

Digestive system|

* Electrogastrogram
* Magnetogastrography

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Medical test. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Medicine:Medical_test&oldid=4171466"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template