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The diagnosis of LAM can be difficult because many of the early symptoms are similar to other lung diseases. 
Often the person with LAM first goes to the doctor complaining of chest pain and shortness of breath that was caused by a pneumothorax.
Some people first talk to their family doctor because they are experiencing shortness of breath upon exertion or a collapsed lung. A family doctor may refer their patient to a lung specialist, known as a respirologist. 
There are a number of tests a doctor can do to confirm or rule out LAM.

Chest X-ray

This is a simple procedure that provides a picture of the lungs and other tissue in the chest. The chest X-ray is used to diagnose a pneumothorax or the presence of fluid in the chest cavity (pleural effusion). Smooth muscle cysts, consistent with LAM, do not usually appear on an X-ray.

Pulmonary Function Tests

The patient breathes through a mouthpiece into a machine (spirometer) that measures the volume of air in the lungs, the movement of air into and out of the lungs, and the movement of oxygen from the lungs into the blood.

Blood Tests

The patient's blood is analyzed to determine whether the lungs are providing an adequate supply of oxygen to the blood.

Computed Tomography (CT)

Computed tomography (CT) is the most definitive imaging test for diagnosing LAM.
The patient lies inside a long, cylindrical structure, and X-ray beams pass through the body from different angles, producing multiple images. A computer combines all of these images and provides a 3-dimensional picture of the inside of the lungs and chest. This is called a CT scan.
On a CT scan, the presence of thin-walled cysts spread relatively uniformly throughout the lungs usually means LAM.
A CT scan should also be done of the abdominal area, as there is a benign kidney tumor called angiomyolipoma that is associated with LAM.

Lung Biopsy

A lung biopsy might be used to diagnose LAM. In this procedure, a few small pieces of lung tissue are removed through an incision made in the chest wall between the ribs.