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Measures of CF

Cystic fibrosis (CF) progression can be measured in a number of ways. Below are some of the most common tests that can help determine the impact and progression of CF.

Measuring Disease Impact

FEV1

One of the most common tests used to measure CF progression is a pulmonary function test, of which one component is FEV1, or forced expiratory volume in 1 second. This is done during the spirometry test. The FEV1 test is usually done after age 6.

But FEV1 does not always change at the beginnings of lung damage and disease progression. There are other tests that may find lung damage and disease progression earlier.

Computed tomographic (CT) scans

A CT scan is an x-ray technique that shows much greater detail by using multiple images of a body part, put together by a computer, to form a detailed image. Since it takes a photo of the lungs, damage may be visible early on.

Magnetic resonance imaging (MRI)

An MRI produces images of specific body parts, similar to x-rays and CT scans, but without the exposure to radiation. The use of MRI testing in people with CF continues to evolve, which leads to more accurate test results. It's important to keep in mind that MRI is today considered a research tool.

Lung clearance index (LCI)

LCI is a test that is sometimes used during clinical trials of CF medicines. It measures how much air is getting to all the different parts of the lungs when someone breathes. It is considered to be more sensitive than the FEV1 test, so in the early stages of lung disease it may catch early progression sooner.

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Other tests besides FEV1 can be used in order to detect early lung damage.

Because FEV1 doesn't always find progression when it begins, healthcare providers may also look to other tests to assess lung function.

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Other Measures of CF

It's a good idea to have a conversation with the care team about tests that can measure disease impact and progression.

Learn more about these tests and what they measure by clicking below or rolling over each part of the body.

Learn more about these tests and what they measure below.

Albumin-to-creatinine ratio (ACR) - Kidneys
  • Urine is tested for a type of protein called albumin
  • Determines if kidneys have a problem filtering blood, which could lead to kidney disease
Audiometry - Ears
  • Headphones are attached to an audiometer that sends controlled tones with different intensity to one ear at a time
  • Provides precise measurement of hearing
Bacterial culturing - Lungs
  • A throat or sputum culture or bronchoscopy is used to collect bacteria from the lungs
  • Identifies what kinds of bacteria are present and the best medicine to treat them
Blood sugar testing - Pancreas
  • A finger stick that uses a needle or a continuous glucose monitor tests levels in the blood
  • Helps people with CF keep their glucose levels in check and control CFRD
Body mass index (BMI) - Other parts of the body
  • Weight and height are measured to determine amount of body fat
  • Assesses nutritional status
C-reactive protein (CRP) - Liver
  • A blood sample is tested for levels of C-reactive protein
  • Checks inflammation throughout the body when CRP levels rise but is not specific; it cannot pinpoint an exact location or cause
Dual energy x-ray absorptiometry (DEXA) - Bones
  • A special kind of x-ray with low radiation takes a picture of the bones
  • Measures bone mass
  • Measures vitamin D levels
Fecal elastase-1 - Pancreas
  • A single stool sample is measured for the pancreatic digestive enzyme, elastase-1
  • Assesses how well the pancreas is working. If elastase-1 is low, it usually means the pancreas isn't working well
Glomerular filtration rate (GFR) - Kidneys
  • Blood is tested for a protein called creatinine and then a math formula is used to measure the level of kidney function and determine the extent of kidney damage
Immunoreactive trypsinogen (IRT) - Pancreas
  • A dried spot of blood is analyzed for IRT, usually in the first few days of life
  • Determines how well someone's pancreas works. IRT is found in higher amounts in babies with CF
Liver function test - Liver
  • A blood sample is tested for certain proteins and enzymes
  • Helps determine how well the liver is functioning
Palpation of the abdomen - Liver
  • A test done by a healthcare provider in which they press on the liver to determine size, tenderness, or masses
  • Helps healthcare providers identify signs of liver disease
Sinus endoscopy - Sinuses
  • A small camera is used to look in the sinuses
  • Assesses the extent of disease in the sinuses
Sweat chloride levels - Other parts of the body
  • Sweat is collected, weighed, and chloride concentration is measured
  • Sweat chloride is a measure of CFTR function
  • Helps to diagnose someone with CF
Bones
Dual energy x-ray absorptiometry (DEXA)
  • A special kind of x-ray with low radiation takes a picture of the bones
  • Measures bone mass
  • Measures vitamin D levels
Other parts of the body
Sweat chloride levels
  • Sweat is collected, weighed, and chloride concentration is measured
  • Sweat chloride is a measure of CFTR function
  • Helps to diagnose someone with CF
Body mass index (BMI)
  • Weight and height are measured to determine amount of body fat
  • Assesses nutritional status
Ears
Audiometry
  • Headphones are attached to an audiometer that sends controlled tones with different intensity to one ear at a time
  • Provides precise measurement of hearing
Kidneys
Albumin-to-creatinine ratio (ACR)
  • Urine is tested for a type of protein called albumin
  • Determines if kidneys have a problem filtering blood, which could lead to kidney disease
Glomerular filtration rate (GFR)
  • Blood is tested for a protein called creatinine and then a math formula is used to measure the level of kidney function and determine the extent of kidney damage
Liver
Liver function test
  • A blood sample is tested for certain proteins and enzymes
  • Helps determine how well the liver is functioning
Palpation of the abdomen
  • A test done by a healthcare provider in which they press on the liver to determine size, tenderness, or masses
  • Helps healthcare providers identify signs of liver disease
C-reactive protein (CRP)
  • A blood sample is tested for levels of C-reactive protein
  • Checks inflammation throughout the body when CRP levels rise but is not specific; it cannot pinpoint an exact location or cause
Lungs
Bacterial culturing
  • A throat or sputum culture or bronchoscopy is used to collect bacteria from the lungs
  • Identifies what kinds of bacteria are present and the best medicine to treat them
Pancreas
Immunoreactive trypsinogen (IRT)
  • A dried spot of blood is analyzed for IRT, usually in the first few days of life
  • Determines how well someone's pancreas works. IRT is found in higher amounts in babies with CF
Blood sugar testing
  • A finger stick that uses a needle or a continuous glucose monitor tests levels in the blood
  • Helps people with CF keep their glucose levels in check and control CFRD
Fecal elastase-1
  • A single stool sample is measured for the pancreatic digestive enzyme, elastase-1
  • Assesses how well the pancreas is working. If elastase-1 is low, it usually means the pancreas isn't working well
Sinuses
Sinus endoscopy
  • A small camera is used to look in the sinuses
  • Assesses the extent of disease in the sinuses
Spine Different parts Ears Kidneys Liver Lungs Pancreas Sinuses

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