Cystic fibrosis other diagnostic studies
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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 is an indicator of 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 insufficency.
- Sweat chloride test should performed as soon as possible (even in 48 hours after birth) when positive screening results are reported.
- 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)
- In patients with cystic fibrosis the absence of functional CFTR (alterations in chloride efflux and sodium transport) produces an abnormal electrical potential difference across epithelial surfaces.[5]
- NPD is performed by running different solutions through the nose. Voltage measurements from these solutions are used to detect changes in CFTR function.[6]
- Patients with CF may have one of following NPD findings:[5][7]
- 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 mucosa with amiloride, an inhibitor of epithelial sodium channels.
- Minimal change in NPD in response to perfusion with amiloride/low chloride/beta-agonist, as a measure of defective chloride transport via CFTR.
Pulmonary function tests (PFTs)
- 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.[8]
References
- ↑ Pettit RS, Fellner C (July 2014). "CFTR Modulators for the Treatment of Cystic Fibrosis". P T. 39 (7): 500–11. PMC 4103577. PMID 25083129.
- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ 5.0 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.
- ↑ Pettit RS, Fellner C (July 2014). "CFTR Modulators for the Treatment of Cystic Fibrosis". P T. 39 (7): 500–11. PMC 4103577. PMID 25083129.
- ↑ 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) - ↑ 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.