All are symptoms of acute mountain sickness except-
**Core Concept**
Acute mountain sickness (AMS) is a condition that occurs when the body cannot adapt to high altitudes, leading to a range of symptoms due to hypoxia. The pathophysiology involves impaired gas exchange, increased pulmonary artery pressure, and decreased oxygen delivery to tissues. Key symptoms include headache, fatigue, and shortness of breath.
**Why the Correct Answer is Right**
The symptoms of acute mountain sickness include headache, fatigue, shortness of breath, dizziness, and nausea. These symptoms occur due to the body's inability to adapt to the lower oxygen levels at high altitudes. The primary mechanism involves the accumulation of 2,3-bisphosphoglycerate (2,3-BPG) in red blood cells, which shifts the oxygen-hemoglobin dissociation curve to the right, impairing oxygen delivery to tissues.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is a common symptom of acute mountain sickness. Headache is a classic symptom of AMS, often described as a dull, throbbing pain.
* **Option B:** This option is incorrect because it is a symptom of acute mountain sickness. Fatigue is a common complaint in individuals with AMS, often accompanied by weakness and lethargy.
* **Option C:** This option is incorrect because it is a symptom of acute mountain sickness. Shortness of breath (dyspnea) is a hallmark symptom of AMS, often occurring even at rest.
**Clinical Pearl / High-Yield Fact**
Mnemonics can be helpful in remembering the symptoms of acute mountain sickness. The "Lake Louise Criteria" is a widely used mnemonic, which includes headache, fatigue, shortness of breath, dizziness, and nausea as key symptoms.
**Correct Answer:** D