Sickle Cell at Mile High Clark vs. Altitude in Broncos Playoff
Posted 1/4/2012 12:01 AM by Nicole Garneau |
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Science at Altitude:
Sports Authority Field at Mile High is exactly that -- at
a Mile High, 5280 feet above sea level. High altitude means two
things in terms of oxygen and decreased air pressure:
1. Less oxygen molecules
2. Less air pressure to help push air into our lungs when we
breathe
These two factors cause hypoxia (no or low oxygen getting
to the cells in your body). Why is oxygen so important? Oxygen is a
key factor in how our cells make energy. When cells
have oxygen and glucose (sugar) a reaction occurs that makes energy
(in the form of ATP, the body's energy currency) and has the
byproducts of water and carbon dioxide.
So without oxygen, our bodies can't make energy
efficiently and our cells, tissue and eventually organs can stop
working. This is what happened to Ryan Clark last time he played at
Mile High, except his situation is even more complicated, because
of having sickle cell. But let's look at what the body normally
does, and then we'll take a closer look at sickle cell at high
altitude.
For folks coming in from sea level, like the Pittsburg
Steelers for the 2011 playoff game against the Broncos, there are
two stages of adaptation the body must go through to ensure oxygen
levels stay topped off within the body:
1. Short term adaptation: The body immediately starts to
concentrate red blood cells (which contain hemoglobin, the molecule
that carries oxygen) by filtering out liquid from the blood. This
is why when you first come to high altitude you will have to go to
the bathroom more and part of the reason why dehydration can be
such an issue.
2. Long term adaptation: The kidneys immediately start
sending chemical signals (erythropoietin) to the bone marrow to get
them to make more red blood cells (and therefore more hemoglobin
molecule in the red blood cells to carry oxygen). Over a period of
time (anywhere from a few days to a couple weeks) a person will
have topped off their red blood cells.
In the case of Ryan Clark and folks with sickle cell, this
process is complicated. Your DNA is like a cookbook for your body.
Each recipe in the DNA cookbook is a gene, and tells your body how
to make one important thing your body needs. People with sickle
cell disease have a change to the recipe/gene that tells the body
how to make hemoglobin. Since hemoglobin is located in red blood
cells, the molecule affects the shape of these cells. Normal
hemoglobin allows red blood cells to be circular; with sickle cell
the shape of the red blood cells is more crescent-shaped. The
sickle cell crescent-shaped red blood cells can clog up blood flow,
restricting the ability for the blood to deliver oxygen to cells
around the body.
This is a genetic disease. Since you get one copy of each
gene from mom and one from dad, a person can have two mutated
copies, or sometimes might only get one mutated copy. With two
mutated copies of the gene/recipe, the disease is more grave then
having only one copy of the mutated gene because all the hemoglobin
the body makes is from the mutated recipe, so all red blood cells
are crescent-shaped, increasing the chances that blood flow will be
restricted. My understanding is that Ryan Clark has only one
mutated gene/recipe for making hemoglobin (he got one normal gene
from one parent and one mutated one from his other parent), and so
for the most part he is asymptomatic under normal
conditions.
At high altitude however, your body is concentrating red
blood cells. For folks with sickle cell, this means the body is
increasing the number of sickle cell red blood cells in the same
amount of liquid. This dramatically increases the chance that the
sickle cell crescent-shaped red blood cells will clog up the
arteries and therefore restrict blood flow, causing cell death, and
organ failure.
Your body is a complicated and fascinating thing, and the
more we understand about how genes/recipes work, and how the body
reads and makes things from recipes (gene expression) the more we
will understand both health and disease.
If you want to how your body adapts to high altitude and
will be in the Denver area, come visit Expedition Health at the
Denver Museum of Nature & Science, which takes you on a virtual
hike up Mount Evans, a Colorado fourteen thousand feet peak, and
shows you how your body changes in ways you can see, measure and
optimize.
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