Question:hard
A 29 year old anxious lady presents with progressive breathlessness and exercise intolerance for four months. Her FVC is 90% and FEV1/FVC is 86%. Oxygen saturation after exercise dropped from 92% to 86%. What is the likely diagnosis?
A 29 year old anxious lady presents with progressive breathlessness and exercise intolerance for four months. Her FVC is 90% and FEV1/FVC is 86%. Oxygen saturation after exercise dropped from 92% to 86%. What is the likely diagnosis?
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Normal spirometry but exertional desaturation in a young woman points to the lung vessels.
Updated On: Jun 24, 2026
- Primary alveolar hypoventilation
- Primary pulmonary hypertension
- Anxiety disorder
- Interstitial lung disease
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The Correct Option is B
Solution and Explanation
The clinical thread is a young woman who is slowly getting more breathless and tires on exertion, and who drops her oxygen when she exercises. The job is to find a cause that fits these features while her breathing tests look normal.
Her spirometry is the key filter. An FVC of 90 percent and an FEV1 over FVC ratio of 86 percent are both normal, so the airways are not obstructed and the lung volumes are not restricted. That immediately weakens any diagnosis that depends on abnormal mechanics.
Yet she desaturates from 92 down to 86 percent with activity. Exercise-induced desaturation in the face of clean spirometry points away from the airways and toward the pulmonary circulation or gas transfer. The classic disease that combines a young female patient, slowly worsening breathlessness, exertional desaturation, and normal lung volumes is idiopathic, or primary, pulmonary hypertension. So that option is the best answer.
The rest do not hold. Interstitial lung disease should restrict the lungs and lower the FVC, but the FVC is normal. Primary alveolar hypoventilation is a chronic CO2 retention syndrome that does not match this profile. Anxiety can mimic breathlessness but cannot drop the true arterial oxygen saturation, and her measured fall in SpO2 marks a real organic problem.
$$\boxed{\text{Primary pulmonary hypertension}}$$
Her spirometry is the key filter. An FVC of 90 percent and an FEV1 over FVC ratio of 86 percent are both normal, so the airways are not obstructed and the lung volumes are not restricted. That immediately weakens any diagnosis that depends on abnormal mechanics.
Yet she desaturates from 92 down to 86 percent with activity. Exercise-induced desaturation in the face of clean spirometry points away from the airways and toward the pulmonary circulation or gas transfer. The classic disease that combines a young female patient, slowly worsening breathlessness, exertional desaturation, and normal lung volumes is idiopathic, or primary, pulmonary hypertension. So that option is the best answer.
The rest do not hold. Interstitial lung disease should restrict the lungs and lower the FVC, but the FVC is normal. Primary alveolar hypoventilation is a chronic CO2 retention syndrome that does not match this profile. Anxiety can mimic breathlessness but cannot drop the true arterial oxygen saturation, and her measured fall in SpO2 marks a real organic problem.
$$\boxed{\text{Primary pulmonary hypertension}}$$
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