A type of blood pressure that affects the arteries in the lungs is known as pulmonary arterial hypertension. If you are wondering what the causes of PAH are, then it should be noted that the exact cause of the condition is unknown. However, there are certainly significant factors that are thought to cause PAH. These are mentioned below. 

1. Injury
At the top of the list of the causes of PAH is damage or injury to the cells that line the small blood vessels in the lungs. This can occur due to unknown reasons. The injury or damage could cause the smooth muscle cells to contract, resulting in the constricting of arteries.

2. Genetics
Researchers believe that 15-20% of patients with PAH have inherited the condition. Changes or mutations in the BMPR2 gene can result in the development of PAH. However, with ongoing studies and research, other gene mutations and pathways have also been identified as factors that contribute to the development of PAH.

3. Certain medications
Studies have found an increased risk of developing PAH if you use appetite-suppressing medications such as dexfenfluramine and fenfluramine for more than three months. Although these medications have been taken off the market by the Food and Drug Administration (FDA), other diet pills and medication are available that can also be factors for PAH. In addition to diet pills, other medications that can cause PAH are methamphetamines and dasatinib.

4. Health conditions
If you are trying to list the causes of PAH, then you can make a note of certain medical or health conditions such as liver disease (cirrhosis) and connective tissue disease that includes scleroderma and congenital heart disease. Scleroderma is a chronic autoimmune disease that affects the skin. PAH is a severe complication of this health condition. In some rare cases, people with HIV can also develop PAH.

5. Lung conditions
The most common when considering the causes of PAH are are lung conditions such as chronic obstructive pulmonary disease, better known as COPD, obstructive sleep apnea, and interstitial lung disease or pulmonary fibrosis. These conditions reduce the amount of oxygen in the lungs. This can result in the arteries getting narrow and an increase in blood pressure in the lungs.

6. Blood clots
Although a rare condition, this can also be listed when answering what are the causes of PAH. A pulmonary embolism would block or obstruct blood flow in the arteries, increasing blood pressure in the lungs. To dissolve these clots, you can ask your doctor for anticoagulants. However, when the clots do not dissolve, they form scar tissue that blocks blood flow.

Being aware of the causes of PAH can help you notice symptoms and seek treatment for this condition at the earliest.