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©2022 American Medical Writers Association. All rights reserved.  
ISSN 2163-5315

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Shakespeare’s Juliet asked, “What’s in a name? That which 

we call a rose / by any other name would smell as sweet.” 

(Romeo and Juliet Act II, Scene II, Line 46-47) But Juliet 

was a love-struck teenager. The Chinese philosopher 

Confucius gave advice that is more suitable for medical 

writers: “If names be not correct, language is not in accor-

dance with the truth of things. If language be not in accor-

dance with the truth of things, affairs cannot be conducted 

successfully.” (Analects Section 3, Part 13) A diagnosis is a 

kind of name—a name that must be used accurately. Real 

estate professionals tell us that the value of a property is 

determined by 3 factors: location, location, and location. 

Likewise, the care that a patient receives will hinge on diag-

nosis, diagnosis, diagnosis. As medical writers, we need to 

understand what a diagnosis is, and what the process of 

diagnosis entails.

 When I am sick, I want my clinician (physician, nurse 

practitioner, or physician assistant) to give me 4 vital pieces 

of information:

• What is wrong with me? (diagnosis)

• Why did this happen? (etiology)

• What can be done about it? (therapeutics)

• What will happen to me because of all this? (prognosis)

 Sometimes, the answer to the first question will prac-

tically dictate the answers to the rest of the questions. If I 

receive a diagnosis of influenza, it means that my clinician 

thinks that my illness resulted from infection with an influ-

enza virus. This diagnosis will affect how my illness will be 

treated and the predictions that will be made about what 

will happen to me next.

WHAT IS A DIAGNOSIS?
The word diagnosis came from ancient Greek. Dia- came 

from a root that meant “through, in different directions, or 

between,” but could also mean “thoroughly,” and gnosis 

meant knowledge. So, the word diagnosis implied a form of 

knowledge that was chosen from among a set of possibil-

ities. Likewise, pro- meant “before,” so a prognosis meant 

foreknowledge—a prediction. Many things can go wrong 

with the human body. A diagnosis implies that the clinician 

knows something about what has gone wrong in a particular 

case. A prognosis is the clinician’s educated guess of what 

will happen in the future.

 Diagnosis is a noun, but it has been transformed into the 

verb to diagnose. Thus, diagnosis can be viewed as a pro-

cess, not just as the label that is applied to the patient’s ill-

ness at the completion of the process. Differential diagnosis 

can mean the process of choosing from among 2 or more 

conditions that produce a similar clinical picture. However, 

a differential diagnosis can also mean the list of possible 

explanations for a patient’s condition. Each item on the list 

is a diagnostic differential.

 The ancient Greek philosopher Plato suggested that 

knowledge is a justified true belief.1 A diagnosis is a belief 

that is (one hopes) justifiable. Ideally, there would be some 

consensus within the scientific community and the med-

ical profession about how each diagnosis can or should 

be justified. Some diagnoses can be justified by some sort 

of pathognomonic sign or symptom (ie, something that is 

distinctively characteristic of that condition). Others are 

justified by the result of imaging or a laboratory test. The 

justification could be a formal case definition—a set of cri-

teria that must be met. Yet even if a diagnosis seems to meet 

the appropriate criteria, it could still be wrong.

 Medical students are taught heuristics for diagnosis. A 

heuristic is an approach to problem-solving. The word heu-

ristic came from the Greek verb heuriskein, which means 

to discover. One approach is to consider the most common 

conditions first—yet rare diseases do occur, albeit rarely. 

Another approach is to try to find a single diagnosis that 

explains every aspect of the patient’s condition, because 

the simplest explanation is most likely to be correct. This 

is in line with the principle called Occam’s Razor: “entities 

should not be multiplied beyond necessity.” Yet Occam’s 

Razor must be balanced against Hickam’s Dictum: “a 

patient can have as many diseases as he damn well pleases.”

 Clinicians can make errors in diagnosis for countless rea-

sons. However, those errors all fall into 2 basic categories:

• A misdiagnosis means that the patient was given a diag-

nosis of a condition that he or she did not really have. 

A misdiagnosis is easy to make when several different 

Laurie Endicott Thomas, MA, ELS  /  Madison, NJ

What’s in a Name? (Diagnosis)

IN THE SERVICE OF GOOD WRITING

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AMWAJournal.org     26What’s in a Name? (Diagnosis)

diseases produce similar signs and symptoms. A 

misdiagnosis can also result from a false-positive 

result from a diagnostic test.

• A missed diagnosis (also known as a failure to  

diagnose) means that the clinician failed to pro-

vide the correct diagnosis. This problem can be 

due to a false-negative result from a diagnostic 

test. It can also result from a failure of imagina-

tion called premature closure of the differential: a 

failure to include the correct diagnosis among the 

differentials being considered.2

These individual errors can add up to a systematic 

under- or overdiagnosis of a disorder.

• Underdiagnosis means that the condition is being  

missed in a significant proportion of cases.  

Under-diagnosis is common when the popula-

tion has poor access to medical care, when there 

is poor awareness of the condition among the 

population and/or the clinicians, or when the 

correct diagnosis is hard to make.

• Overdiagnosis means that too many patients are 

being given the diagnosis. The diagnosis is being 

given to patients who do not have the condition 

at all and/or it is being given to patients whose 

cases are too mild to warrant medical attention. 

Overdiagnosis can be a result of disease mon-

gering, which is the practice of inappropriately 

widening the diagnostic criteria for a medical 

condition and aggressively promoting public 

awareness, to expand the market for diagnostics 

and treatments.

For the individual patient, an error in diagnosis can 

lead to bad treatment decisions and bad outcomes. 

On a societal level, these individual errors may result 

in poor public health and large-scale misallocation of 

resources.

DIAGNOSES ARE LABELS
A diagnosis is a label that is applied to a patient’s ill-

ness. This labeling allows clinicians and scientists to 

sort cases of illness into categories and to sort patients 

into groups, which makes it possible to do clini-

cal studies. Some diagnostic labels imply the kind of 

knowledge that the clinician believes that he or she has 

about the patient’s condition. Others refer to the pro-

cess through which the clinician’s belief was justified 

(see Types of Diagnosis).

Types of Diagnoses
admitting diagnosis—the diagnosis reported by the clinician who decided that  
the patient needs to be hospitalized. The admitting diagnosis may be tentative 
because the patient has yet to undergo examinations and testing. The admitting 
diagnosis is recorded for administrative purposes.

biologic diagnosis—a diagnosis based on a test performed on a laboratory  
animal (eg, inoculation of a cell culture, egg, or laboratory animal with a 
patient’s specimen to isolate a virus).

clinical diagnosis—a diagnosis based on the patient’s symptoms and clinical  
signs at examination, as well as the patient’s history. Symptoms are phenomena 
(eg, pain) that are subjective (ie, only the patient can observe them). Clinical 
signs are phenomena (eg, swelling, heat, or redness) that are objective (ie, the 
examining clinician can observe them). The term clinical diagnosis can also 
mean a diagnosis that was based on all the information (including laboratory 
and imaging results) available during the patient’s lifetime, as compared with 
the autopsy findings.

cytologic diagnosis—diagnosis based on examination of exfoliated (shed) cells.

definitive diagnosis—a final diagnosis based on the results of confirmatory 
testing.

diagnosis of exclusion—a diagnosis made by eliminating all of the other  
known differentials.

diagnosis ex juvantibus—a diagnosis based on the result of treatment, such as 
antibiotic therapy.

direct diagnosis—a diagnosis made by observing structural lesions or 
pathognomonic signs or symptoms. Pathognomonic means distinctly  
characteristic of a particular disease.

discharge diagnosis—the diagnosis recorded when the patient leaves the 
hospital.

etiologic diagnosis—a diagnosis that implies the underlying cause of an illness  
(eg, a diagnosis of measles means that the clinician believes that the patient has 
a measles virus infection), or the process of identifying the underlying cause 
of the illness (eg, isolation of a particular strain of bacteria in the case of an 
infection).

faux diagnosis—a false diagnosis that is made for some administrative 
purpose.

laboratory diagnosis—a diagnosis based on the results of tests or  
examinations performed in a laboratory on specimens (eg, of tissue or bodily 
fluids) taken from the patient.

niveau diagnosis—localization of the exact level (niveau in French) of a  
lesion, such as in the spinal cord.

pathologic diagnosis—a diagnosis based on the observed presence of 
structural lesions. The clinicopathologic method meant comparing the  
records of the patient’s condition during lifetime with the autopsy findings.

physical diagnosis—a diagnosis based on looking at (inspection), feeling 
(palpation), tapping on (percussion), and listening to (auscultation) the 
patient’s body.

presumptive diagnosis—a diagnosis based on the known probability of a 
known condition, such as the antemortem diagnosis of a disorder that can  
be confirmed only at autopsy. (Compare with definitive diagnosis.)

provocative diagnosis—a diagnosis based on a provocative test, such as 
exposure to an allergen to confirm an allergy.

radiologic diagnosis—a diagnosis based on the results of imaging, such as  
x-ray imaging, computed tomography, or magnetic resonance imaging.

serum diagnosis—a diagnosis based on testing of serum (the fluid left after a 
blood sample coagulates).

syndromic diagnosis—the recognition of a group of signs and symptoms that 
characterize a clinical condition that might not always result from the same 
cause. The word syndrome came from the Greek for “occurring together.” If 
research shows that a particular syndrome always results from a particular 
cause, the syndrome becomes a disease.

wastebasket diagnosis—a vague and possibly meaningless diagnosis given 
when a patient’s condition cannot be easily classified.

working diagnosis—the differential (or set of differentials) that is considered 
most likely to be the true diagnosis.

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AMWAJournal.org     27What’s in a Name? (Diagnosis)

Cause or Effect?
Diagnoses are labels that allow us to sort cases. However, 

diagnostic labels themselves can be sorted into categories, 

such as etiologic (ie, pertaining to cause) vs syndromic  

(ie, pertaining to the pattern of observable effects). Some 

diagnoses (eg, the classic exanthems) start off as a syn-

dromic diagnosis, only to become an etiologic diagnosis as 

its cause is revealed. An exanthem is an acute, sudden ill-

ness that involves a widespread rash along with other symp-

toms (eg, fever and headache). By the early 10th century, 

the Persian physician Abū Bakr Muhammad ibn Zakariyyā 

al-Rāzī (known in the West as Rhazes) knew that smallpox 

and measles were separate diseases. Yet the causes of those 

2 diseases remained unknown for another millennium. In 

the early 20th century, pediatricians assigned numbers to 

the most common childhood exanthems (Box: The Classic 

Exanthems).3 These disorders began as clinical syndromes. 

But in the 20th century, researchers found that each of these 

classic exanthems (except for fourth disease, which might 

not exist as a separate entity) was due to a different infec-

tious agent. Thus, 5 out of the 6 classic exanthems became 

diseases, and the diagnoses changed from syndromic to  

etiologic diagnoses.

Names and Numbers
Medical conditions often had 2 names: the popular name 

and the scientific name (eg, measles and rubeola). A med-

ical condition was often named after the person who first 

described it in the medical literature (eg, Cushing’s syn-

drome). Today, AMA style requires us to drop the ’s after  

the person’s name (Cushing syndrome). Sometimes, the 

name of a condition changes. For example, dementia  

praecox became schizophrenia, and manic-depression 

became bipolar disorder. Sometimes, the name is changed 

because the cause is discovered (eg, “De Vivo syndrome” 

became “glucose transporter type 1 deficiency syndrome”). 

In May 2015, the World Health Organization recommended 

that new diseases should not be named after persons or 

refer to geographical locations, animals, foods, cultural 

or occupational groups, or populations or industries and 

should not include terms that incite undue fear (eg, fatal).4 

If you are uncertain of the current name of a condition, 

you might look it up under the Medical Subject Headings 

thesaurus of the National Library of Medicine (https://

www.ncbi.nlm.nih.gov/mesh). Genetic disorders are cata-

logued in Online Medical Inheritance in Man (https://www.

omim.org/), a joint effort between the National Library of 

Medicine and Johns Hopkins University.

 To make it easier to record medical diagnoses and 

compile statistics on public health, the World Health 

Organization introduced the International Classification of 

Diseases and Related Health Problems. The 11th edition, 

which is currently being implemented, provides roughly 

55,000 unique alphanumeric codes for diseases, injuries, 

and causes of death. For example, the code for a distal frac-

ture of right radius with dorsal tilt and joint involvement 

after falling on the sidewalk would be NC32.50 & XK9K & 

XJ5GS / PA60 & XE53A.5 Similarly, the American Psychiatric 

Association’s Diagnostic and Statistical Manual, currently 

in its fifth revision (DSM-5), is used in the United States for 

coding mental disorders.

Binaries, Scales, and Spectrum Diagnoses
Many common diagnoses involve some sort of binary. A 

binary is some variable that can have one of 2 values: on or 

off, yes or no, alive or dead, male or female, pregnant or not 

pregnant. Yet in practice, even a yes-or-no question has 3 

possible answers: yes, no, and no answer. Although a binary 

involves 2 categories that are separate conceptually, the 

boundary between the 2 categories may be fuzzy in prac-

tice. Thus, it can be hard to classify some individuals. For 

example, a child’s biological sex is a diagnosis that used to 

be made at birth but is now often made much earlier, during 

an ultrasound examination. Nearly every human being can 

easily be classified as either male or female on the basis of 

their phenotype (their anatomy) or their karyotype (pres-

ence or absence of a Y chromosome). Nevertheless, there 

are a few cases (about 1 in 5,500 live births)6 in which a new-

born’s external anatomy does not match the chromosomal 

sex or cannot be easily classified. These rare cases do not 

prove that sex is nonbinary. Rather, they just illustrate that 

the boundary between the 2 categories is slightly fuzzy.

 Even if the boundary between categories is a single clear 

criterion, some cases can be misclassified if the criterion is 

The Classic Exanthems
In the early 20th century, pediatricians numbered the most 
common childhood exanthems (diseases that caused a rash 
and other symptoms, such as fever)3:

• First disease was rubeola (measles)
• Second disease was scarlet fever
• Third disease was rubella (German measles)
• Fourth disease was Duke’s disease (unknown today)
• Fifth disease (erythema infectiosum or slapped cheek 

syndrome) is still called fifth disease
• Sixth disease was roseola infantam.

Measles, rubella, fifth disease, and roseola are caused by 
viral infections. Scarlet fever results from a bacterial infection 
(group A Streptococcus).

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https://www.ncbi.nlm.nih.gov/mesh
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AMWAJournal.org     28What’s in a Name? (Diagnosis)

hard to document. For example, a woman is either pregnant 

or not pregnant. By definition, a pregnancy begins when an 

embryo implants itself on the inner lining of the uterus. Yet 

the pregnancy cannot be detected by blood or urine tests 

until a few days after implantation.

 Many diagnoses depend on some sort of measurement 

(body weight, blood pressure measurements, IQ scores) 

that falls somewhere on a scale. This kind of diagnosis raises 

important questions: is the measurement accurate? Is the 

scale meaningful? Where should the lines between catego-

ries be drawn? Consider the diagnosis of obesity. Obesity 

means that the body contains too much fat. Yet body fat 

content (adiposity) is rarely measured directly. Instead, 

clinicians measure body weight (in kilograms) and divide 

it by the square of the height (in meters) to calculate the 

body mass index. Body mass index provides a useful rule 

of thumb. However, bodybuilders can have a body mass 

index in the obese range despite having very little body fat. 

Also, the body mass index tends to underestimate body fat 

in short people and overestimate it in tall people.7 Yet even 

if you developed a better metric than body mass index, you 

would still have to decide where to draw the lines between 

the categories of underweight, normal weight, overweight, 

and obese. Even if you draw those lines in reasonable 

places, someone whose weight falls close to the boundary 

between categories could switch from one to the other and 

back within the course of a single day.

 Sometimes, differences in magnitude can seem to pro-

duce differences in kind. If a patient receives a different 

diagnosis than another patient received, the difference in 

labeling seems to imply that the 2 patients have different 

kinds of problem. Yet the 2 patients might have the same 

underlying kind of problem but at different levels of severity. 

A spectrum disorder is a set of conditions that look different 

but are believed to represent the same underlying problem 

at different levels of severity,8 just as light at different wave-

lengths looks like different kinds of light.

Psychiatric Diagnoses and the Biopsychosocial Model
Psychiatric diagnoses pose a particularly thorny set of prob-

lems. In general, a mental illness can be any problem that 

involves one or more of the following: cognition (percep-

tions and thoughts), emotion (feelings), or action (behav-

ior). To be considered a mental disorder, a mental illness 

must cause distress or disability, must not be an expectable 

or culturally sanctioned response to a particular event, and 

must not be primarily a result of social deviance or conflict 

with society. Unfortunately, these concepts are broad and 

lack precise boundaries.

 Some mental disorders may have a purely biological 

cause. Others seem to result from a combination of biolog-

ical, psychological, and social causes. The biopsychosocial 

model accepts that all 3 kinds of causes can contribute and 

may be interrelated. Psychiatry is part of medicine because 

many mental disorders are believed to have at least some 

basis in biology. Yet once a particular condition is shown to 

have a clear biological basis (eg, psychosis due to anti-N-

methyl-D-aspartate receptor encephalitis), that condition 

tends to get reclassified as a neurologic disease as opposed 

to a mental disorder. As a result, psychiatry is left with a set 

of conditions whose etiology is unknown or is so compli-

cated that it might never be untangled. For this reason, psy-

chiatric diagnoses are generally syndromic (ie, based on a 

pattern of signs and symptoms) as opposed to etiologic  

(ie, a statement of cause). Thus, psychiatrists use diagnostic 

testing to rule out medical diagnoses, as opposed to con-

firming psychiatric diagnoses.

 When trying to figure out the cause of a mental disor-

der, some psychiatrists prefer to err on the side of biology 

whereas others prefer to err on the side of psychosocial 

causes. Medical writers should be alert for either kind of 

bias. In particular, medical writers should be skeptical 

whenever a diagnostic label suggests that a patient’s phys-

ical symptoms are psychological in origin.9 Conversely, 

medical writers should also be skeptical of the use of medi-

cal-sounding diagnoses for social or educational problems. 

In 1851, Samuel A. Cartwright argued that slaves who tried 

to escape from slavery were exhibiting a mental illness that 

he called drapetomania.10 Today, children who have trou-

ble with the “3 R’s” (reading, writing, and arithmetic) are 

routinely given the diagnoses of dyslexia, dysgraphia, and 

Key Points
When writing about any diagnosis, think carefully about what 
that diagnostic label means.

• Is the diagnostician asserting something about the cause 
of the patient’s condition? Or does the diagnosis simply 
mean that the signs and symptoms follow a familiar 
pattern?

• How is that diagnosis justified? Is it supported by 
physical examination findings, radiologic findings, or the 
results of laboratory testing?

• How meaningful are the criteria for making the 
diagnosis, and how reliably are they being applied?

• How severe must a case of a condition be to qualify 
for the diagnosis? How were the boundaries between 
normal and abnormal values determined?

• Is the diagnostic label saying something true about 
the patient? Or is it sending a misleading message that 
undermines the patient’s interests?

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AMWAJournal.org     29What’s in a Name? (Diagnosis)

dyscalculia. This use of these medical terms implies that the 

cause of the problem is in the child’s brain, when the cause 

of the child’s poor academic performance could very well 

be in the child’s schooling (eg, bad methods for teaching 

reading and math and a refusal to teach penmanship). If we 

are using a medical label for a problem whose cause is ped-

agogical, not medical, then (to paraphrase Confucius) our 

language is not in accordance with the truth of things, and 

our affairs cannot be conducted successfully. 

Author declaration and disclosures: The author notes no 

commercial associations that may pose a conflict of interest 

in relation to this article.

Author contact: lthomas521@verizon.net

References
1. Plato. Meno. Jowett B, trans. Accessed April 21, 2022. http://

classics.mit.edu/Plato/meno.html 

2. Kumar B, Kanna B, Kumar S. The pitfalls of premature closure: 
clinical decision-making in a case of aortic dissection. Case Rep. 
2011. https://doi.org/10.1136/bcr.08.2011.4594

3. Shapiro L. The numbered diseases: first through sixth. JAMA. 
1965;194(6):680.

4. World Health Organization. World Health Organization best 
practices for the naming of new human infectious diseases. World 
Health Organization website. Published May 15, 2015. Accessed 
April 21, 2022.  https://www.who.int/publications/i/item/WHO-
HSE-FOS-15.1

5. Harrison JE, Weber S, Jakob R, Chute CG. ICD-11: an international 
classification of diseases for the twenty-first century. BMC Med 
Inform Decis Mak. 2021;21(Suppl 6):206. 

6. Kim KS, Kim J. Disorders of sex development. Korean J Urol. 
2012;53(1):1-8.

7. Nuttall FQ. Body mass index: obesity, BMI, and health: a critical 
review. Nutr Today. 2015;50(3):117-128.

8. Hodges H, Fealko C, Soares N. Autism spectrum disorder: 
definition, epidemiology, causes, and clinical evaluation. Transl
Pediatr. 2020;9(Suppl 1):S55-S65.

9. Thomas LE. Are your patient’s medically unexplained symptoms 
really “all in her head”? Med Hypotheses. 2012:78(4):542-547.

10. Cartwright SA. Report on the diseases and physical peculiarities of 
the Negro race. N Orleans Med Surg J. 1851;691-715.

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http://www.amwajournal.org
http://classics.mit.edu/Plato/meno.html
http://classics.mit.edu/Plato/meno.html
https://doi.org/10.1136/bcr.08.2011.4594
https://www.who.int/publications/i/item/WHO-HSE-FOS-15.1
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