Sarcoidosis And The Lungs: How Sarcoidosis Affects Lung Function

Imagine getting easily fatigued and out of breath, only to find out after a difficult process, that an obscure disease called sarcoidosis is slowly reducing your lung function. This tragic condition may not be well-known, but its effects on the lungs can be severe, especially for certain groups. 

This article aims to raise awareness of how sarcoidosis impacts lung function, which is important given the lack of widespread knowledge about this condition, making it harder to diagnose.

Sarcoidosis symptoms can resemble other diseases, making it difficult to diagnose and treat. However, some experience spontaneous resolution without treatment as the disease resolves itself. 

Read on to raise your awareness about how sarcoidosis affects lung function. Your understanding can play a vital role in supporting those impacted!

Introduction

Definition of sarcoidosis

Sarcoidosis is a complex condition that causes inflammation in various parts of the body. It results in the formation of tiny clusters of inflammatory cells called granulomas all over the body, These granulomas are characteristic of the condition. They can negatively affect the function of the different organs.¹

While the exact cause of sarcoidosis is unknown, it is believed that genetic and environmental factors have a role to play.²

Importance of understanding sarcoidosis in the lungs

The lungs are one of the most commonly affected organs in sarcoidosis patients,¹ making it crucial to understand how this condition impacts respiratory function. When granulomas form in the lungs, they can cause a variety of symptoms such as shortness of breath, persistent coughing, and in severe cases, injury and scarring of the lung tissue (pulmonary fibrosis), which can be life-threatening.³

The ability to recognise sarcoidosis in the lungs is an essential first step for improving the overall well-being and quality of life of those affected.

Common organs affected by sarcoidois

While sarcoidosis can develop in any organ in the body, it most frequently affects the lungs and lymph nodes.¹ Other commonly involved areas include the skin, eyes, liver, and spleen.⁴ The involvement of multiple organs can lead to a range of symptoms, making sarcoidosis difficult to recognise. 

The distribution of sarcoidosis

Sarcoidosis is found worldwide, with varying incidence across different regions.¹ It is most common among individuals aged 30 to 55 years but can affect people of any age.¹ In the United Kingdom, the incidence of sarcoidosis is estimated to be around 5 per 100,000 people every year.⁵ 

How Sarcoidosis causes disease in the lungs

Formation of granulomas

The peculiar feature of sarcoidosis is the formation of non-caseating granulomas, which are compact clusters of inflammatory cells. These granulomas are made up of the immune cells that normally protect against foreign bodies.

Granulomas can either be: caseating or non-caseating.

The difference is that in caseating granulomas, there is a centre made up of dead (also known as necrotic) cells, while in non-caseating granulomas, the centre is not made up of dead cells. 

The exact trigger that initiates the formation of granulomas in sarcoidosis is unknown, but it is believed to require a combination of an exaggerated immune response to environmental or infectious stimuli, and a genetically predisposed individual.²

Immune system involvement

Although we do not know what exactly triggers the formation of these granulomas, we know that sarcoidosis is characterised by an abnormal response of the immune system to a foreign body (or antigen).²

The immune response in sarcoidosis is dysregulated, with an imbalance between factors that promote inflammation and those that do not. This favours the former and leads to persistent inflammation and granuloma formation.²

Stages of Lung Involvement

Sarcoidosis can involve the lungs in different stages, depending on the extent and distribution of the granulomas. The stages are classified based on radiographic findings:

1. Stage 1 (Bilateral Hilar Lymphadenopathy): In this stage, granulomas form in the lymph nodes, causing the nodes’ enlargement and swelling. This is known as bilateral hilar lymphadenopathy⁶
2. Stage 2 (Bilateral Hilar Lymphadenopathy and Pulmonary Infiltrates): In addition to hilar lymphadenopathy, granulomas also develop in the lung tissue, leading to formations known as pulmonary infiltrates visible on chest imaging⁶
3. Stage 3 (Pulmonary Infiltrates without Hilar Lymphadenopathy): This stage is characterised by the presence of sarcoidosis in the lungs without lymph node involvement⁶
4. Stage 4 (Pulmonary Fibrosis): In this advanced stage, inflammation and granuloma formation can lead to permanent scarring and fibrous tissue formation, causing significant impairment of lung function⁶

Symptoms of pulmonary(lung) sarcoidosis

Respiratory symptoms

Persistent cough 

Many patients with pulmonary sarcoidosis experience a dry, persistent cough that is made worse by physical activity or exposure to certain allergens.¹

Shortness of breath 

As the disease progresses, granulomas can occupy space otherwise needed for proper breathing, resulting in shortness of breath or dyspnea, especially during exertion.¹

Chest pain

Some patients may experience chest pain or discomfort, which may be due to the inflammation of the lungs or the surrounding structures.¹

Systemic symptoms

Fatigue

Overwhelming fatigue and a general feeling of tiredness are common complaints in patients with sarcoidosis, even in those with minimal lung involvement.⁴

Fever

Sarcoidosis can be associated with low-grade fever or episodes of high fever, depending on the extent of inflammation.^[7]

Weight loss      

Unexplained weight loss can occur in individuals with sarcoidosis, possibly due to the increased metabolic demand associated with the inflammatory process.⁷

Diagnosis of lung sarcoidosis

Medical history and physical examination

The diagnostic process for pulmonary sarcoidosis begins with a thorough medical history. Things that the healthcare provider will ask about include the patient's symptoms, potential exposures, and any family history of sarcoidosis or other lung diseases, among other things.  

Imaging studies

Chest X-ray

A chest X-ray is usually the preferred imaging study that is performed because it reveals the stage of the condition (discussed above) that the patient is currently experiencing.¹

CT scan

High-resolution computed tomography (HRCT) scan of the chest provides more detailed information about the presence, distribution, and characteristics of granulomas in the lungs and lymph nodes.^[1]

Impact of sarcoidosis on lung function

Impaired gas exchange

Granulomas in the lungs can interfere with normal gas exchange while breathing. This leads to a decreased amount of oxygen getting to the other organs in the body. This can cause respiratory failure.⁸

Reduced lung volume

Sarcoidosis can cause a restrictive lung disease pattern. This is characterised by an overall reduced lung volume which is caused by the accumulation of granulomas in the lung tissue. This makes the lungs unable to expand and fill with air.⁹

Airway obstruction

In some cases, sarcoidosis can cause airway obstruction when granulomas form in the bronchial walls or compress the airways. This leads to symptoms that make it difficult to differentiate from asthma or chronic obstructive pulmonary disease (COPD).¹⁰

Potential for pulmonary fibrosis

In advanced or chronic stages, persistent inflammation and granuloma formation can lead to pulmonary fibrosis, an irreversible scarring of lung tissue, further reducing lung function.³

Treatment and management

Medications

Healthcare providers decide whether treatment is necessary in each case because the symptoms can differ in severity, However, some of the most common treatments include:

Corticosteroids

Corticosteroids, such as prednisone, are some of the most common drugs of choice for pulmonary sarcoidosis. They suppress the inflammatory response and reduce the overall granuloma formation.¹²

Unfortunately, long-term use of these drugs can lead to side effects.¹³

Immunosuppressive agents

When corticosteroids are not effective or are associated with significant side effects, immunosuppressive agents may be used. They prevent the immune system from ‘overreacting’ and attacking healthy cells. A common example is methotrexate.¹²

Monitoring and follow-up

Regular monitoring of lung function, via imaging studies, and symptoms is an essential part of the follow-up process. This is done to evaluate the effectiveness of treatment and identify the progression or complications of the disease.

Lifestyle and supportive measures

Smoking cessation

Quitting smoking is crucial for individuals with pulmonary sarcoidosis, as smoking can increase the risk of complications.¹⁴

Physical activity

Regular and moderate physical activity can improve energy levels, reduce fatigue, and help manage other symptoms such as shortness of breath and muscle weakness.¹⁴

Mental health support

Sarcoidosis can take a toll on mental health, leading to feelings of anxiety or depression. Counselling, joining support groups, and seeking support from family and friends can help individuals cope with the challenges of living with this condition.¹⁴

Adequate sleep

Prioritising good quality sleep, aiming for 7 to 9 hours per day, is essential for overall well-being and managing fatigue associated with sarcoidosis.¹⁴

Long-term outlook and complications

Long-term outlook

In many cases, pulmonary sarcoidosis can be effectively managed with appropriate treatment, leading to a favourable long-term outlook. However, a handful of patients may experience persistent or recurrent symptoms, requiring ongoing monitoring and treatment.⁶

Potential complications

Despite treatment, some patients with pulmonary sarcoidosis may develop serious complications, including:

Respiratory failure

Severe lung involvement can lead to respiratory failure, requiring supplemental oxygen or even supported breathing in advanced cases.⁸

Pulmonary fibrosis

As sarcoidosis progresses, persistent inflammation and granuloma formation in the lungs can lead to the formation of scar tissue in the lungs. This is known as pulmonary fibrosis and it can significantly impair lung function.³

Summary

Sarcoidosis is a complex, multi-system inflammatory disorder characterised by the formation of granulomas in various organs, most commonly affecting the lungs. Lung involvement in sarcoidosis can lead to a range of respiratory complications, including impaired gas exchange, and scarring of the lungs.

Living with lung sarcoidosis can be an incredibly challenging journey. The impact it has on your ability to breathe and carry out daily activities can be overwhelming and disheartening at times. However, there is hope. Early diagnosis and starting the right treatment plan are key to gaining control over this condition and preventing further lung damage down the road.

If you've been experiencing persistent coughing, shortness of breath, fatigue, or other concerning symptoms, don't hesitate to speak up to your doctor.