Cystic Fibrosis

Cystic fibrosis is an incurable genetic disease. It evolves with obstruction of the ducts of the glands that make thick mucus.
Cystic Fibrosis
Leonardo Biolatto

Written and verified by el médico Leonardo Biolatto.

Last update: 28 May, 2023

Cystic fibrosis is a genetic condition. In other words, it’s a disease that occurs due to an alteration in the genes and is expressed with changes in the conformation of the mucus of some body organs.

The problem is that the mucus thickens and clogs the ducts where it should flow elastically. This is the case of the bronchi in the lungs or the intestine that must receive the flows of other digestive organs, such as the pancreas and the liver.

In basic terms, the respiratory and digestive systems are the most affected. This determines the severity, as both participate in vital functions essential to life, such as breathing and eating.

What mechanism is involved in the pathogenesis of cystic fibrosis?

Pathogenesis is the way in which a disease develops. In other words, the way in which normal physiology is altered, leading to a disorder that doesn’t respond to normality. In the case of cystic fibrosis, this is explained by the involvement of the cells that produce fluids.

Here, sweat and mucus are involved. So are the fluids that carry enzymes from the pancreas and liver to the small intestine for digestion. Although the problem with perspiration would appear to be the least problematic, this isn’t the case. By not sweating properly, the risk of dry skin and dehydration is high, with the consequence of infections and electrolyte imbalances.

All of these secretions are thickened by the underlying genetic alteration. Fluidity is lost and the ducts become clogged because the liquid that must circulate through them, coming out from the glands, doesn’t lubricate, but quite the opposite.

In short, it’s not misleading to think of the disease as a disorder of glandular lubrication. In the medium term, each altered fluid leads to complications that explain the symptoms. Obstructed bronchial tubes favor pneumonia, the digestive system loses functionality, and sweat doesn’t serve to eliminate waste toxins.

An adult with cystic fibrosis.
Adults can be diagnosed with the disease already advanced, although it’s not as common.

The symptoms of cystic fibrosis

Cystic fibrosis has severe symptoms. In general, it’s rare for a patient to present with mild signs or signs that don’t cause significant alterations in their daily life. In addition, since it begins at birth, from minute zero, there are problems and complications that require medical attention.

Although there are registered cases of children who began with the symptoms later and not from birth, these cases are very rare. Adult or adolescent onsets have also been reported.

The truth is that the passing of time results in a worsening of the clinical picture. The longer it takes to reach a diagnosis, the less chance of effective treatment is. Even so, the therapeutic approaches aren’t curative but rather regulate the quality of life to improve it, within what’s possible.

The mildest symptom of cystic fibrosis is increased salinity of sweat. This is explained by the hydroelectrolytic imbalance of the sweat glands that produce thick perspiration, which is unable to eliminate sodium, so they retain it. It can be detected by the patient themself if they’re old enough to express themself, when sweat comes into contact with their tongue.

Lung symptoms

In the lungs, the issue with this disease is more complicated. The thick secretions of the bronchi obstruct them and the respiratory dynamics are hindered. The lung tissue must apply more force to complete inspiration and, above all, expiration.

Wheezing accounts for the forced passage of air. These are high-pitched, whistling sounds when you breathe. At the same time, air capacity is reduced and the patient is unable to sustain long-term exercises, giving up with dyspnea in a short time.

Respiratory infections are increasing. The risk of pneumonia or bronchitis is high because part of the function of mucus is to eliminate pathogens. By not being able to carry out this basic task, agents that cause disease are retained.

Digestive symptoms

As we’ve said, the digestive system is also majorly affected by this disease. Cystic fibrosis can express itself, in the first instance, with a malabsorption syndrome. This is a condition in which the body is unable to enter nutrients into the blood by altering the mucosa of the jejunum and ileum.

The explanation lies in the pancreatic and hepatic channels that are obstructed due to the thickness of the secretions. Then, the enzymes that should help with digestion don’t reach the right place and the food continues its course without being absorbed.

The usual symptoms are constipation, nausea, and bloating. All this leads the patient with cystic fibrosis to eat less, with less appetite and associated consequences. There’s weight loss due to poor nutrition and even anemia.

The genetics of  cystic fibrosis

At the beginning of this article, we said that cystic fibrosis is a genetic disease. This is because its etiology lies in changes in the genes, specifically in what is known as the CFTR. This is the acronym for the “cystic fibrosis transmembrane conductance regulator”.

In other words, this gene in question is the one that allows the expression of a protein that’s located in cells as a chlorine channel. Through its transport function, it’s a regulator of the balance of electrolytes and water that enter and leave the metabolism. The glands use the protein to make secretions that are normal.

If there’s an alteration in the CFTR gene, a defective protein is produced, and the exchange of chlorine and cellular water is inefficient. Consequently, the mucus thickens because it doesn’t have enough liquid to lubricate. Similarly, the sodium within the fluids increases, which explains the salinity of the sweat.

Not all CFTR genetic alterations are the same. This determines the severity of the clinical picture, based on the different mutations. In one way or another, the transmission is by inheritance; parents pass it on to their children.

A doctor looking at a chest x-rat.
Pulmonary complementary methods help in the diagnosis of bacterial superinfections.

How is the disease diagnosed?

Cystic fibrosis can be diagnosed at birth with a test that, in many countries, is free and compulsory in maternity wards. In general, the analysis is included in a complete scan that’s usually combined with that of congenital hypothyroidism.

What’s tracked is the presence of trypsinogen in neonates. This proenzyme, that is, the protein that will later become the active form of the enzyme, must be present within already established normal values. When trypsinogen is elevated in the blood from birth, then the suspicion is more evident and requires other complementary methods to confirm.

The next step after suspicion is to confirm with a sweat test. In fact, this test is almost always the one of choice, as it has a high sensitivity and specificity for cystic fibrosis. What it measures is the salinity of sweat.

Another series of complementary methods can be performed in patients in whom a pulmonary complication is suspected, which is quite frequent. In those cases, when a fever and a different cough than usual appear, doctors should order X-rays and sputum tests.

Cystic fibrosis treatment

There’s no cure for cystic fibrosis. This disease is chronic and there’s no way to reverse it. The aim is to control complications, reduce symptoms that affect the quality of life, and prolong well-being as long as possible. The prognosis is almost never ideal.

As for the drugs that are prescribed, the range is wide. It must be considered that, sometimes, it’s necessary to treat infectious complications with antibiotics and, other times, reducing inflammation of the tissues to improve the flow of fluids is required. Among the most used, we have the following:

  • Non-steroidal anti-inflammatory drugs: The idea of using these drugs is to reduce the inflammation present in the bronchi, for example, to improve respiratory dynamics. They’re also good analgesics when associated with discomfort.
  • Bronchodilators: One option to counteract thick mucus in the lungs is to dilate the bronchial tubes with medications, similar to those used for asthma and COPD. Inhalers such as salbutamol are an option, as is its use via nebulizers.
  • Antibiotics: Antibiotics are used when there are super-aggregated infections, especially in the lungs. Before prescribing them, professionals must confirm the bacteria involved, so a sputum culture of the secretions and an antibiogram are required.

Interventional approaches

As complex as it is, cystic fibrosis requires interventions that invade the patient’s body. Oral medications are far from being enough. Complications require procedures such as catheter placement. A nasogastric tube is usually the alternative to ensure adequate nutrition.

As a support therapy for bronchial obstruction, respiratory kinesiotherapy comes to the aid. There are complicated patients in whom several sessions a day are needed to favor the exit of mucus through the nose or mouth. If this fails, the next step is catheter aspiration.

A person preparing a nebulizer.
Cystic fibrosis medications can be taken by mouth or inhaled.

A disease that can’t be prevented or cured

Cystic fibrosis can’t be prevented, nor can it be cured. It’s a disease that evolves seriously, putting the lives of patients at serious risk. It usually begins in childhood. This makes it more dramatic, as it implies a commitment from the whole family and caregivers to ensure the well-being of the child.

More and more is known about the disease, but the genetic aspect can’t be prevented at present. The closest thing we have is a timely diagnosis at birth with mandatory screening to implement quick measures to alleviate evolution.

  • Castaños, C., and Fernando Rentería. “Consenso nacional de fibrosis quística.” Arch Argent Pediatr 106.5 (2008): 34-35.
  • Palma, Alejandra Graciela, Basilio Aristides Kotsias, and Gabriela Inés Marino. “Funciones de los canales iónicos CFTR y ENAC en la fibrosis quística.” (2014).
  • de Gracia, Javier, et al. “Fibrosis quística del adulto: estudio de 111 pacientes.” Medicina Clínica 119.16 (2002): 605-609.
  • Aspiazu-Hinostroza, Karla Alexandra, et al. “Revisión Bibliográfica sobre la Fibrosis Quística.” CEUS 1.1 (2019): 19-24.
  • Maté, JM Borro, et al. “El trasplante pulmonar en la fibrosis quística.” An Esp Pediatr 45 (1996): 505-510.
  • Borges, Maribel Suárez, et al. “Evaluación nutricional de pacientes con fibrosis quística.” MediSan 17.04 (2013): 661-668.
  • Lay-Son, Guillermo, and Gabriela Repetto. “Genética y fibrosis quística: desde el gen CFTR a los factores modificadores.” Neumología pediátrica 5 (2010): 4-9.
  • Moscoso, G. “Actualización en kinesiología respiratoria en pacientes con fibrosis quística.” NEUMOLOGIA PEDIÁTRICA (2017).
  • Quintana-Gallego, Esther, Isabel Delgado-Pecellín, and Carmen Calero Acuña. “Tratamientos reparadores de la proteína CFTR en la fibrosis quística.” Archivos de bronconeumología 50.4 (2014): 146-150.
  • Sánchez, Ignacio, et al. “Comparación entre dos métodos de determinación del test del sudor en el diagnóstico de la fibrosis quística.” Revista chilena de pediatría 70.4 (1999): 281-287.
  • García, Miguel Ángel Martínez, Juan José Soler Cataluña, and Pablo Catalán Serra. “Antibióticos inhalados en el tratamiento de las bronquiectasias no debidas a fibrosis quística.” Archivos de Bronconeumología 47 (2011): 19-23.
  • Fuster, Gabriel Olveira, and María Laínez López. “Importancia del soporte nutricional en adultos con fibrosis quística.” Endocrinología y Nutrición 53.5 (2006): 326-334.

Este texto se ofrece únicamente con propósitos informativos y no reemplaza la consulta con un profesional. Ante dudas, consulta a tu especialista.