Understanding Raised Haemoglobin in Dehydration
The patient presents with symptoms of significant fluid loss: severe diarrhoea and vomiting. This leads to dehydration and hypotension (low blood pressure).
Physiological Impact of Dehydration
Dehydration causes a decrease in the plasma volume within the blood. Haemoglobin concentration is measured as the amount of haemoglobin per unit of blood volume.
- When the plasma volume decreases, the concentration of red blood cells, including haemoglobin, increases relative to the total blood volume.
- This makes the measured haemoglobin level appear higher than the patient's actual red blood cell mass.
Identifying Relative Polycythaemia
A haemoglobin level of $19$ gm% in this context is most likely due to haemoconcentration caused by dehydration.
- Relative polycythaemia is characterized by an increase in haemoglobin concentration due solely to a decrease in plasma volume, without an actual increase in red blood cell production.
- The patient's clinical presentation (hypotension, dehydration) strongly supports this diagnosis.
Differentiating Other Conditions
- Secondary polycythaemia involves increased red blood cell production due to factors like hypoxia or tumours, which is less likely given the acute symptoms.
- Polycythaemia vera is a bone marrow disorder causing overproduction of red blood cells, typically presenting more chronically.
- Essential thrombocythaemia involves increased platelet production, not primarily haemoglobin.
Therefore, the most likely reason for the raised haemoglobin is relative polycythaemia resulting from dehydration.
Important Questions from General Clinical Conditions
- The height of the Jugular Venous Pulse is determined by :
- The SA node is situated at the junction of:
- Reverse splitting of second heart sound is most commonly seen in :
- A 70-year-old man with dyspnoea on exertion has been found to have a single second heart sound and a loud diamond-shaped, rough quality systolic murmur best heard at the right $2^{nd}$ intercostal space, radiating to the right carotid artery. Which one of the following is the likely diagnosis ?
Consider the following statements with regard to pulmonary embolism :
1. Unexplained breathlessness is the most common symptom.
2. When congestive heart failure or pneumonia fail to improve despite standard medical treatment, occult pulmonary embolism should be considered.
3. Patients with high clinical likelihood of venous thromboembolism should first undergo D-dimer testing alone without obligatory imaging tests.
Which of the statements given above are correct?
