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{{Cystic fibrosis}}
{{Cystic fibrosis}}


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{{CMG}}; {{AE}} {{SHH}}


==Overview==
==Overview==
Other diagnostic studies in patients with cystic fibrosis include [[Sweat test|sweat chloride test]] (measures the [[chloride]] content of the sweat) and nasal potential differences (performed by running different solutions through the nose) which used to detect changes in [[Cystic fibrosis transmembrane conductance regulator|CFTR]] function. A sweat [[chloride]] value of more than 59 mmol/L is diagnostic for cystic fibrosis and less than 30 mmol/L indicates that cystic fibrosis is unlikely. Also [[Spirometry|Pulmonary function test (PFT)]] is important in monitoring [[lung]] function in patients with cystic fibrosis. However, it is only an indirect measure of [[lung]] structure and is [[Sensitivity (tests)|insensitive]] to local or early damage.


==Other Diagnostic Studies==
== Other Diagnostic Studies ==
[[Spirometry|Pulmonary function tests]] measure how well the lungs are functioning, and are used to measure the need for and response to antibiotic therapy. [[Dual energy X-ray absorptiometry|DEXA scans]] can [[Screening (medicine)|screen]] for osteoporosis and testing for [[fecal elastase]] can help diagnose insufficient digestive enzymes.  
Other diagnostic studies in patients with cystic fibrosis include:<ref name="pmid25083129">{{cite journal |vauthors=Pettit RS, Fellner C |title=CFTR Modulators for the Treatment of Cystic Fibrosis |journal=P T |volume=39 |issue=7 |pages=500–11 |date=July 2014 |pmid=25083129 |pmc=4103577 |doi= |url=}}</ref><ref name="pmid16773960">{{cite journal |vauthors=Shah U, Moatter T |title=Screening for cystic fibrosis: the importance of using the correct tools |journal=J Ayub Med Coll Abbottabad |volume=18 |issue=1 |pages=7–10 |date= 2006 |pmid=16773960 |doi= |url=}}</ref><ref name="pmid28129811">{{cite journal |vauthors=Farrell PM, White TB, Ren CL, Hempstead SE, Accurso F, Derichs N, Howenstine M, McColley SA, Rock M, Rosenfeld M, Sermet-Gaudelus I, Southern KW, Marshall BC, Sosnay PR |title=Diagnosis of Cystic Fibrosis: Consensus Guidelines from the Cystic Fibrosis Foundation |journal=J. Pediatr. |volume=181S |issue= |pages=S4–S15.e1 |date=February 2017 |pmid=28129811 |doi=10.1016/j.jpeds.2016.09.064 |url=}}</ref><ref name="pmid281298112">{{cite journal |vauthors=Farrell PM, White TB, Ren CL, Hempstead SE, Accurso F, Derichs N, Howenstine M, McColley SA, Rock M, Rosenfeld M, Sermet-Gaudelus I, Southern KW, Marshall BC, Sosnay PR |title=Diagnosis of Cystic Fibrosis: Consensus Guidelines from the Cystic Fibrosis Foundation |journal=J. Pediatr. |volume=181S |issue= |pages=S4–S15.e1 |date=February 2017 |pmid=28129811 |doi=10.1016/j.jpeds.2016.09.064 |url=}}</ref>


===Prenatal diagnosis===
=== '''Sweat chloride test''' ===
Couples who are pregnant or who are planning a pregnancy can themselves be tested for CFTR gene mutations to determine the likelihood that their child will be born with cystic fibrosis. Testing is typically performed first on one or both parents and, if the risk of CF is found to be high, testing on the [[fetus]] can then be performed. Cystic fibrosis testing is offered to many couples in the US.<ref>ACOG Committee Opinion #325: ''Update on Carrier Screening for Cystic Fibrosis.'' Obstet Gynecol 2005; 106:1465.</ref> The [[American College of Obstetricians and Gynecologists]] (ACOG) recommends testing for couples who have a personal or close family history.  Additionally, ACOG recommends that carrier testing be offered to all Caucasian couples and be made available to couples of other ethnic backgrounds.<ref>American College of Obstetricians and Gynecologists and American College of Medical Genetics. ''Preconception and prenatal carrier screening for cystic fibrosis. Clinical and laboratory guidelines.''American College of Obstetricians and Gynecologists, Washington, DC, October 2001.</ref>
* [[Sweat test|Sweat chloride test]] is an indicator of [[Cystic fibrosis transmembrane conductance regulator|CFTR]] function and measures the [[chloride]] content of the sweat in the patients with cystic fibrosis. This test is critical to distinguish cystic fibrosis from other causes of severe pulmonary and [[Pancreatic insufficiency|pancreatic insufficency]].  
* [[Sweat test|Sweat chloride test]] should performed as soon as possible (even in 48 hours after birth) when positive [[Screening (medicine)|screening]] results are reported.  


Because development of CF in the fetus requires each parent to pass on a mutated copy of the CFTR gene and because CF testing is expensive, testing is often performed on just one parent initially. If that parent is found to be a carrier of a CFTR gene mutation, the other parent is then tested to calculate the risk that their children will have CF. CF can result from more than a thousand different mutations and, as of 2006, it is not possible to test for each one. Testing analyzes the blood for the most common mutations such as ΔF508 &mdash; most commercially available tests look for 32 or fewer different mutations. If a family has a known uncommon mutation, specific screening for that mutation can be performed. Because not all known mutations are found on current tests, a negative screen does not guarantee that a child will not have CF.<ref>Elias, S, Annas, GJ, Simpson, JL. ''Carrier screening for cystic fibrosis: Implications for obstetric and gynecologic practice. Am J Obstet Gynecol 1991; 164:1077. PMID 2014829</ref> In addition, because the mutations tested are necessarily those most common in the highest risk groups, testing in lower risk ethnicities is less successful because the mutations commonly seen in these groups are less common in the general population.  These couples may therefore consider testing through labs that offer CF screens with a high number of mutations tested.
* [[Sweat test|Sweat chloride test]] results are considered as follow:
** '''More than 59 mmol/L:''' diagnostic for cystic fibrosis
** '''30-59 mmol/L:''' needs more evaluation with [[Cystic fibrosis transmembrane conductance regulator|CFTR]] [[Genetic testing|genetic analysis]]
** '''Less than 30 mmol/L:''' unlikely cystic fibrosis


Couples who are at high risk for having a child with CF will often opt to perform further testing before or during pregnancy. [[In vitro fertilization]] with [[preimplantation genetic diagnosis]] offers the possibility to examine the [[embryo]] prior to its placement into the uterus. The test, performed 3 days after [[fertilization]], looks for the presence of abnormal CF genes. If two mutated CFTR genes are identified, the embryo is not used for [[embryo transfer]] and an embryo with at least one normal gene is implanted.
{{familytree/start |summary=Sweat chloride test}}
{{familytree | | | | | | | | | A01 |A01=[[Sweat chloride test]]}}
{{familytree | | | |,|-|-|-|-|-|+|-|-|-|-|-|.| | | }}
{{familytree | | | B01 | | | | B02 | | | | B03 | | |B01=≥60 mmol/L|B02=30-59 mmol/L|B03=≤29 mmol/L}}
{{familytree | | | |!| | | | | |!| | | | | |!| }}
{{familytree | | | |!| | | | | C01 | | | | |!| | |C01=[[CFTR]] [[genetic analysis]]}}
{{familytree | | | |!| | | | | |!| | | | | |!| }}
{{familytree | | | |!| | | |,|-|^|-|.| | | |!| }}
{{familytree | | | |!|,|-| D01 | | D02 |-|.|!| | |D01=2 [[CFTR]] [[mutations]] causing CF|D02=No [[CFTR]] [[mutations]]}}
{{familytree | | | |!|!| | | | | | | | | |!|!| }}
{{familytree | | | |!|!| | | | | | | | | |!|!| }}
{{familytree | | | E01 | | | | | | | | | | E02 |E01=CF diagnosis|E02=CF unlikely}}
{{familytree/end}}


During pregnancy, testing can be performed on the [[placenta]] ([[chorionic villus sampling]]) or the fluid around the fetus ([[amniocentesis]]). However, [[chorionic villus sampling]] has a risk of fetal death of 1 in 100 and amniocentesis of 1 in 200,<ref>Tabor A, Philip J, Madsen M, Bang J, Obel EB, Norgaard-Pedersen B. ''Randomised controlled trial of genetic amniocentesis in 4606 low-risk women.'' Lancet. 1986 Jun 7;1(8493):1287–93. PMID 2423826</ref> so the benefits must be determined to outweigh these risks prior to going forward with testing. Alternatively, some couples choose to undergo [[third party reproduction]] with [[Egg donor|egg]] or [[sperm donation|sperm donors]].
=== '''Nasal Potential Difference (NPD)''' ===
*In patients with cystic fibrosis the absence of functional [[Cystic fibrosis transmembrane conductance regulator|CFTR]] (alterations in [[chloride]] efflux and [[sodium]] transport) produces an abnormal electrical [[potential difference]] across [[Epithelium|epithelial]] surfaces.<ref name="pmid19092437">{{cite journal |vauthors=Moskowitz SM, Chmiel JF, Sternen DL, Cheng E, Gibson RL, Marshall SG, Cutting GR |title=Clinical practice and genetic counseling for cystic fibrosis and CFTR-related disorders |journal=Genet. Med. |volume=10 |issue=12 |pages=851–68 |date=December 2008 |pmid=19092437 |pmc=2810953 |doi=10.1097/GIM.0b013e31818e55a2 |url=}}</ref>
*NPD is performed by running different solutions through the nose. Voltage measurements from these solutions are used to detect changes in [[Cystic fibrosis transmembrane conductance regulator|CFTR]] function.<ref name="pmid250831292">{{cite journal |vauthors=Pettit RS, Fellner C |title=CFTR Modulators for the Treatment of Cystic Fibrosis |journal=P T |volume=39 |issue=7 |pages=500–11 |date=July 2014 |pmid=25083129 |pmc=4103577 |doi= |url=}}</ref>
*Patients with CF may have one of following NPD findings:<ref name="pmid19092437">{{cite journal |vauthors=Moskowitz SM, Chmiel JF, Sternen DL, Cheng E, Gibson RL, Marshall SG, Cutting GR |title=Clinical practice and genetic counseling for cystic fibrosis and CFTR-related disorders |journal=Genet. Med. |volume=10 |issue=12 |pages=851–68 |date=December 2008 |pmid=19092437 |pmc=2810953 |doi=10.1097/GIM.0b013e31818e55a2 |url=}}</ref><ref name="pmid20301428">{{cite journal |vauthors=Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, Ong T, Marshall SG, Karczeski BA, Sternen DL, Cheng E, Cutting GR |title= |journal= |volume= |issue= |pages= |date= |pmid=20301428 |doi= |url=}}</ref>
** A raised (more negative) baseline NPD reflecting enhanced [[sodium]] absorption across a relatively [[chloride]]-impermeable membrane.
** A greater change in NPD during [[perfusion]] of the nasal [[Mucous membrane|mucosa]] with [[amiloride]], an inhibitor of [[Epithelium|epithelial]] [[Sodium channel|sodium channels]].
** Minimal change in NPD in response to [[perfusion]] with [[amiloride]]/low [[chloride]]/[[Beta2-adrenergic receptor agonist|beta-agonist]], as a measure of defective [[chloride]] transport via [[Cystic fibrosis transmembrane conductance regulator|CFTR]].
 
=== Pulmonary function tests (PFTs) ===
* [[Spirometry|Pulmonary function test (PFT)]] is important in monitoring [[lung]] function in patients with cystic fibrosis. However, it is only an indirect measure of lung structure and is [[Sensitivity (tests)|insensitive]] to local or early damage.<ref name="pmid16938643">{{cite journal |vauthors=Tiddens HA |title=Chest computed tomography scans should be considered as a routine investigation in cystic fibrosis |journal=Paediatr Respir Rev |volume=7 |issue=3 |pages=202–8 |date=September 2006 |pmid=16938643 |doi=10.1016/j.prrv.2006.04.002 |url=}}</ref>


==References==
==References==


{{reflist|2}}
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Latest revision as of 20:19, 29 March 2018

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Shaghayegh Habibi, M.D.[2]

Overview

Other diagnostic studies in patients with cystic fibrosis include sweat chloride test (measures the chloride content of the sweat) and nasal potential differences (performed by running different solutions through the nose) which used to detect changes in CFTR function. A sweat chloride value of more than 59 mmol/L is diagnostic for cystic fibrosis and less than 30 mmol/L indicates that cystic fibrosis is unlikely. Also Pulmonary function test (PFT) is important in monitoring lung function in patients with cystic fibrosis. However, it is only an indirect measure of lung structure and is insensitive to local or early damage.

Other Diagnostic Studies

Other diagnostic studies in patients with cystic fibrosis include:[1][2][3][4]

Sweat chloride test

  • Sweat chloride test results are considered as follow:
    • More than 59 mmol/L: diagnostic for cystic fibrosis
    • 30-59 mmol/L: needs more evaluation with CFTR genetic analysis
    • Less than 30 mmol/L: unlikely cystic fibrosis
 
 
 
 
 
 
 
 
Sweat chloride test
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
≥60 mmol/L
 
 
 
30-59 mmol/L
 
 
 
≤29 mmol/L
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CFTR genetic analysis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2 CFTR mutations causing CF
 
No CFTR mutations
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
CF diagnosis
 
 
 
 
 
 
 
 
 
CF unlikely

Nasal Potential Difference (NPD)

Pulmonary function tests (PFTs)

References

  1. ↑ Pettit RS, Fellner C (July 2014). "CFTR Modulators for the Treatment of Cystic Fibrosis". P T. 39 (7): 500–11. PMC 4103577. PMID 25083129.
  2. ↑ Shah U, Moatter T (2006). "Screening for cystic fibrosis: the importance of using the correct tools". J Ayub Med Coll Abbottabad. 18 (1): 7–10. PMID 16773960.
  3. ↑ Farrell PM, White TB, Ren CL, Hempstead SE, Accurso F, Derichs N, Howenstine M, McColley SA, Rock M, Rosenfeld M, Sermet-Gaudelus I, Southern KW, Marshall BC, Sosnay PR (February 2017). "Diagnosis of Cystic Fibrosis: Consensus Guidelines from the Cystic Fibrosis Foundation". J. Pediatr. 181S: S4–S15.e1. doi:10.1016/j.jpeds.2016.09.064. PMID 28129811.
  4. ↑ Farrell PM, White TB, Ren CL, Hempstead SE, Accurso F, Derichs N, Howenstine M, McColley SA, Rock M, Rosenfeld M, Sermet-Gaudelus I, Southern KW, Marshall BC, Sosnay PR (February 2017). "Diagnosis of Cystic Fibrosis: Consensus Guidelines from the Cystic Fibrosis Foundation". J. Pediatr. 181S: S4–S15.e1. doi:10.1016/j.jpeds.2016.09.064. PMID 28129811.
  5. ↑ 5.0 5.1 Moskowitz SM, Chmiel JF, Sternen DL, Cheng E, Gibson RL, Marshall SG, Cutting GR (December 2008). "Clinical practice and genetic counseling for cystic fibrosis and CFTR-related disorders". Genet. Med. 10 (12): 851–68. doi:10.1097/GIM.0b013e31818e55a2. PMC 2810953. PMID 19092437.
  6. ↑ Pettit RS, Fellner C (July 2014). "CFTR Modulators for the Treatment of Cystic Fibrosis". P T. 39 (7): 500–11. PMC 4103577. PMID 25083129.
  7. ↑ Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean L, Stephens K, Amemiya A, Ong T, Marshall SG, Karczeski BA, Sternen DL, Cheng E, Cutting GR. PMID 20301428. Vancouver style error: initials (help); Missing or empty |title= (help)
  8. ↑ Tiddens HA (September 2006). "Chest computed tomography scans should be considered as a routine investigation in cystic fibrosis". Paediatr Respir Rev. 7 (3): 202–8. doi:10.1016/j.prrv.2006.04.002. PMID 16938643.
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