This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Gaisbock's syndrome refers to: 
Select and explain. 
A. Spurious erythrocytosis, B. Spurious thrombocytosis, C. Reactive thrombocytosis, D. Reactive erythrocytosis
A: Spurious erythrocytosis
Answer: A: Spurious erythrocytosis 
Explanation: Relative Erythrocytosis Hemoconcentration secondary to dehydration, diuretics, ethanol abuse, androgens or tobacco abuse It is Known as stress or spurious erythrocytosis or Gaisbock's syndrome Please NOTE: Not all patients with polycythemia rubra vera exhibit JAK2 mutation. Ref: Harrison, E-18,P-900