Answer
In a male at sea level or near it (586 ft in Chicago) the normal erythrocyte parameters are as follows;
Hematocrit (Hct) 42-54%
Hemoglobin (Hgb) 14-18 gm/dl
Reticulocytes 1-2 %of RBCs
In Tyler's case the data from his blood test are as follows:
Hematocrit 65%
Reticulocyte 5%
Polycythemia positive
In medical and biomedical sciences, a male hematocrit of more that 56% is an indication of the
existence of polycythemia. Tyler is clearly polycythemic, relatively or absolutely. If a person at any altitude with a normal hematocrit become chronically dehydrated , his hematocrit will rise ; that does not mean he his producing more erythrocytes than usual. In this case however , the high percentage of immature erythrocytes-reticulocytes- indicates that the polycythemia is most likely due to increased proliferative activity of the red bone marrow, under the stimulus of increased amount of erythropoietin secreted by the kidneys.
Polycythemia or erythrocytosis, can be due to several kinds of tumors,to dehydration, or to acute mountain sickness(AMS)-- there is also idiopathic polycythemia. In the present circumstances the answer that seems to link all of Tyler's blood test results together is an attempt of his body to acclimate to the low partial gas pressures of a high altitude site where has been located for at least several months.
Work Step by Step
Normal values of blood parameters are as follows:
Normal hematocrit for males 42-54% RBC
[Hemoglobin] 12-18 gm/dl
Reticulocyte 1-2% of RBCs
Polycythemia ( erythrocytosis) Hct. >55% RBCs
Tyler's blood tests shows that he has a hematocrit of 65%, and an reticulocyte count of 5%
The increased hematocrit could be due to dehydration without any significant in crease of bone marrow activity in the production of new reticulocytes and mature erythrocytes. This would be called relative polycythemia. But the increase in the percentage of immature erythrocytes (reticulocytes) by at least three-fold, indicates that the red bone marrow is producing many more erythrocytes than normal. The usual stimulus for increased red bone marrow activity is erythropoietin. Since the normal stimulus for increased kidney output of erythropoietin is hypoxia, and the usual conditions that expose the body to the low gas pressures that generate hypoxia is high altitude, it follows that Tyler has been at high altitude for some time, and that his test result reflect his acclimation or adaptation to a high altitude environment.
