The CF medical abbreviation most often means cystic fibrosis, an inherited condition that makes mucus thick and sticky in the lungs, pancreas and other organs. On a problem list or a lung clinic note, that is almost always the meaning.
Two other readings are common enough to know. In eye exams, CF means count fingers, a way to record very low vision, and in written text cf. with a period is the Latin shorthand for compare. A slashed C/F is something else again. This page sorts out each meaning, shows how they look in real notes, and explains the basics of cystic fibrosis for families and students.
At a glance
Stands for
Cystic fibrosis (most common in charts)Other meanings
Count fingers (eye exams); cf. meaning compareLatin origin
cf. is short for confer, compareSpecialty
Pulmonology, gastroenterology, genetics, ophthalmologyKey test
Sweat chloride test, plus genetic testingDo not confuse with
C/F, which has its own meanings in notes
The main CF medical abbreviation: cystic fibrosis
Cystic fibrosis is caused by changes in both copies of a gene called CFTR, which controls how salt and water move in and out of cells. When the protein made from this gene does not work, the mucus lining the airways and ducts becomes thick. In the lungs it traps germs and leads to repeated infections and inflammation. In the pancreas it blocks the release of digestive enzymes, so food, especially fat, is poorly absorbed. Sweat becomes unusually salty.
CF is inherited in an autosomal recessive pattern. A child is affected when each parent passes on a changed copy, and parents who each carry one copy usually have no symptoms.
How cystic fibrosis is found and followed
In the US, every newborn is screened for CF through the heel prick blood test. A positive screen is followed by a sweat chloride test, which measures salt in sweat. A result of about 60 mmol/L or higher is consistent with CF, and genetic testing looks for CFTR changes. Each lab reports its own reference ranges.
Care is usually led by a specialty center. Notes track lung function with spirometry, the PFT results such as FEV1, sputum cultures, weight and growth. Treatments described in charts include airway clearance, inhaled medicines, enzyme capsules with meals, and CFTR modulator medicines that help the faulty protein work better for many people with certain gene changes.
Count fingers and other readings of CF
| Meaning | Setting | Sample |
|---|---|---|
| Cystic fibrosis | Problem lists, lung and GI clinics, genetics | CF with pancreatic insufficiency |
| Count fingers | Eye exams, visual acuity | VA OS: CF at 3 ft |
| cf. (compare) | Reports and written references | Findings stable, cf. prior CT |
Count fingers is used when a person cannot read the largest letter on the eye chart. The examiner holds up fingers at a set distance and records the farthest distance at which the patient counts them correctly. It sits on a scale with hand motion and light perception for even lower vision. You may see it next to OS, OD or OU.
C/F medical abbreviation when it is not cystic fibrosis
Many people search for the C/F medical abbreviation because they saw it in a note that clearly is not about cystic fibrosis. With a slash, C/F is a separate piece of shorthand, often meaning complains of or chills and fever depending on the writer, and it has its own page. Radiology and pathology reports also use cf. with a period to compare one finding with another.
Eye clinic line: "VA cc OD 20/40, OS CF 2 ft." This means that with glasses the right eye sees 20/40, and the left eye can only count fingers held about two feet away. Nothing here refers to a lung condition.
Reading a cystic fibrosis clinic note
Pulmonary follow-up: "14 yo with CF (F508del homozygous), pancreatic insufficient on enzymes with meals. FEV1 82% pred, down from 90%. Sputum cx: Pseudomonas. Plan: increase airway clearance, inhaled abx, recheck PFTs in 4 wks." F508del names the most common CFTR change, homozygous means two copies, pred means predicted, and cx means culture.
A falling FEV1 or a new germ in sputum often prompts a change in the plan, which is why both are written in nearly every visit note.
Questions families often ask the CF team
- Which CFTR changes does our child have, and do they affect treatment choices?
- How often will lung function and cultures be checked?
- What signs suggest a lung flare that needs a call?
- Should siblings or relatives consider carrier testing?
More condition abbreviations are organized in the diagnosis abbreviations hub.
These are general explanations of the letters CF. For anything about your own or your child's diagnosis, tests or treatment, the CF care center team is the right place to ask.
Frequently asked questions
Which meaning of CF is most common?
In medical charts CF usually stands for cystic fibrosis, an inherited condition affecting the lungs and digestion. In eye exams it means count fingers, and cf. in written reports means compare.
Why would an eye doctor write CF?
On a vision record CF is short for count fingers. The person could not read the eye chart, so the examiner recorded the distance at which they could count fingers held up in front of them.
Is CF the same as C/F?
No. C/F with a slash is different shorthand used in notes, often meaning complains of or chills and fever. CF without a slash in a diagnosis usually means cystic fibrosis.
How is cystic fibrosis diagnosed?
Newborn screening flags many cases. Diagnosis is confirmed with a sweat chloride test and genetic testing for changes in the CFTR gene.
What does cf. mean in a radiology report?
It is from the Latin confer and means compare. A line such as cf. prior study asks the reader to compare the current images with an earlier exam.