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Hypersensitivity Pneumonitis (HP)

Hypersensitivity pneumonitis, or HP, is a disease in which the lungs become inflamed from breathing in foreign substances, such as molds, dusts, and chemicals.

PubMed Health Glossary
(Source: NIH - National Heart, Lung, and Blood Institute)

Hypersensitivity Pneumonitis (HP)

Hypersensitivity pneumonitis is a rare immune system disorder that affects the lungs.

It occurs in some people after they breathe in certain substances they encounter in the environment. These substances trigger their immune systems, causing short- or long-term inflammation, especially in a part of the lungs called the interstitium. This inflammation makes it harder for the lungs to function properly and may even permanently damage the lungs.

If diagnosed, some types of hypersensitivity pneumonitis are treatable by avoiding exposure to the environmental substances or with medicines such as corticosteroids that reduce inflammation.

If the condition goes untreated or is not well controlled over time, the chronic inflammation can cause irreversible scarring of the lungs that may severely impair their ability to function.
NIH - National Heart, Lung, and Blood Institute

What works? Research summarized

Evidence reviews

Diagnosis and Management of Suspected Idiopathic Pulmonary Fibrosis: Idiopathic Pulmonary Fibrosis [Internet]

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrotic interstitial lung disease (ILD) of unknown origin. It is a difficult disease to diagnose and often requires the collaborative expertise of a chest physician, radiologist and histopathologist to reach a consensus diagnosis. Most people with idiopathic pulmonary fibrosis experience symptoms of breathlessness, which may initially be only on exertion. Cough, with or without sputum is a common symptom. Over time, these symptoms are associated with a decline in lung function, reduced quality of life and ultimately death. Specific pharmacological therapies for IPF are limited but the last decade has seen more trials of new drugs which have had a variable impact on clinical practice. A number of difficulties arise when undertaking clinical trials in IPF in terms of defining precise, diagnostic inclusion criteria and clinically meaningful end-points. However, such trials are the only way by which promising new treatments will come to benefit patients. Furthermore, it is only by performing rigorous clinical trials, we have learned that drugs once widely used to treat IPF may in fact have been harmful. The limitations of current pharmacological therapies for IPF highlight the importance of other forms of treatment including lung transplantation and best supportive care such as oxygen therapy, pulmonary rehabilitation and palliation of symptoms. These are interventions which justifiably require scrutiny in the context of healthcare delivery by the modern NHS. Despite the significant burden of disease caused by IPF, there is currently no established framework within the NHS for its diagnosis and management thus creating an environment in which significant variations in clinical care may occur. In recognition of this, the Department of Health commissioned the National Institute of Health and Care Excellence (NICE) to produce a guideline aimed at improving the care of people with IPF.

Adalimumab, etanercept, infliximab, certolizumab pegol, golimumab, tocilizumab and abatacept for the treatment of rheumatoid arthritis not previously treated with disease-modifying antirheumatic drugs and after the failure of conventional disease-modifying antirheumatic drugs only: systematic review and economic evaluation

Study found that for the treatment of rheumatoid arthritis, biologic disease-modifying antirheumatic drugs had cost per quality-adjusted life-year values greater than the thresholds stated by the National Institute for Health and Care Excellence and could not be considered cost-effective.

Drug Class Review: HMG-CoA Reductase Inhibitors (Statins) and Fixed-dose Combination Products Containing a Statin: Final Report Update 5 [Internet]

In the United States, coronary heart disease and cardiovascular disease account for nearly 40% of all deaths each year. Coronary heart disease continues to be the leading cause of mortality and a significant cause of morbidity among North Americans. In 2006, coronary heart disease claimed 607 000 lives, translating into about 1 out of every 5 deaths in the United States. High levels of cholesterol, or hypercholesterolemia, are an important risk factor for coronary heart disease. The 3-hydroxy-3-methylglutaryl-coenzyme (HMG-CoA) reductase inhibitors, also known as statins, are the most effective class of drugs for lowering serum low-density lipoprotein cholesterol concentrations. They are first-line agents for patients who require drug therapy to reduce serum low-density lipoprotein cholesterol concentrations. The purpose of this review is to compare the benefits and harms of different statins in adults and children with hypercholesterolemia.

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Terms to know

Alveoli
Tiny air sacs at the end of the bronchioles (tiny branches of air tubes) in the lungs. The alveoli are where the lungs and the bloodstream exchange carbon dioxide and oxygen. Carbon dioxide in the blood passes into the lungs through the alveoli. Oxygen in the lungs passes through the alveoli into the blood.
Antigens
A foreign substance that triggers the production of antibodies when it is introduced into the body.
Bronchi
The large air passages that lead from the trachea (windpipe) to the lungs.
Inflammation
Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.
Interstitial
An interstitial space or interstice is an empty space or gap between spaces full of structure or matter.
Lungs
One of a pair of organs in the chest that supplies the body with oxygen, and removes carbon dioxide from the body.

More about Hypersensitivity Pneumonitis

Photo of an adult

Also called: Extrinsic allergic alveolitis, Allergic alveolitis, Allergic extrinsic alveolitis, Allergic interstitial pneumonitis, Allergic pneumonitis, Extrinsic allergic bronchiolo-alveolitis, Hypersensitivity pneumonia, EAA

Other terms to know: See all 6
Alveoli, Antigens, Bronchi

Related articles:
How the Lungs Work

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