As
previous blogs have demonstrated there are a variety of conditions that can be of
concern and potentially fatal if not treated quickly by trained
professionals. Some of the topics discussed include sudden cardiac arrest, infectious
mononucleosis, exertional heat illness, an asthma attack, and diabetic emergencies among others. The topic I am going to
discuss today is another one of those topics, sickle cell trait (SCT).
Understanding SCT is particularly important for certain segments of the
population as it is more common in certain ethnic groups. Additionally, exertional sickling and sickling collapse, an emergency condition that can result during intense exercise may sometimes be mistaken for exertional heat
illness (EHI). My goal today is to define SCT, differentiating it from sickle cell
disease (SCD), provide you key identifiers that differentiates SCT from EHI (most
often heat cramps) and provide a brief introduction to the mandated NCAA
testing policy.
SICKLE CELL TRAIT (SCT) BASICS
SCT
is present in those people who inherit one sickle cell gene and one normal gene
(CDC). SCT
can be diagnosed with a simple blood test; infants in the United States are
tested at birth. SCT
is different from sickle cell disease (SCD) because SCD
requires the inheritance of two abnormal genes, one from each parent. This gene results in the mutation of
hemoglobin cells, causing them to take on a crescent or sickle shape (see image below) and making
it more difficult for these cells to transport oxygen.
SCT affects 1 in 12 African Americans, but
the condition can also be prevalent in those with ancestry from South American, the Caribbean, Central American and Mediterranean countries
including Saudi Arabia, India, Turkey, Greece and Italy. As parents, it may be
important that you ask for the results of this test for your new infant. Despite the required
testing most people do not know their sickle cell trait status unless they have
sickle cell disease. People are typically asymptomatic, but there can be potential for complications when the following conditions/situations are present:
- Increased pressure in the atmosphere (ex. when scuba diving)
- Low oxygen levels in the air (ex. very intense training, exertion at altitude)
- Dehydration
- High altitudes
SCT AND ATHLETES
As of this time, there is no recommendation that athletes with SCT should be withheld from participating in sports, however, some
research has shown that athletes can be particularly at risk of complications
from SCT when completing intense training. The possibility of complications can be
enhanced by training in extreme temperatures or at high altitudes (as previously mentioned). The key to SCT is prevention is to set your
own pace, rest often between drills/activities, stay hydrated
before/during/after activity and keep the body as cool as possible when
exercising in hot conditions according to the CDC fact sheet.
For
an individual who has SCT and completing intense exercise the biggest
concern is a condition called exertional sickling (and the resulting sickling collapse). In exertional sickling the intense exercise
causes normal the sickle shaped blood cells to “logjam” the blood vessels,
slowing oxygen transport to the muscles. Muscle tissue begins to breakdown after a prolonged period of a lack of oxygen resulting in a condition referred to as rhabdomyolysis. This condition is a
medical emergency and can lead to death if not treated immediately. The biggest key to proper treatment is
immediate recognition of the condition and proper treatment.
Exertional sickling/sickling collapse can sometimes be confused with exertional heat
illness, particularly heat cramps.
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EXERTIONAL
SICKLING
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EXERTIONAL
HEAT ILLNESS
|
|
Typically
happens within first 30 minutes on the field
|
Typically
happens after prolonged exercise for more than 30 minutes
|
|
Core
temperature is not elevated
|
Core
temperature is typically >1040F
|
|
Pain
is strong and generalized
|
Heat
cramps: muscle twinges and focused
pain
|
|
Typically
slump to ground with weak muscles; sufferers will lie fairly still and muscles
will look and feel normal to the observer
|
Heat
cramps: suffers “hobble” and muscle
are locked up and hard to touch, suffers will yell out/writhe in pain
|
If
you or your athletic trainer suspect exertional sickling the athlete should be
removed from activity immediately.
Oxygen can be administered if available (and someone is trained in its use) and the EAP should be
activated. A sickling collapse is a medical emergency.
RYAN CLARK, PROFESSIONAL ATHLETE WITH POSITIVE SCT STATUS
Want
to know more about an athlete who’s competing in the NFL with sickle cell
trait? Check out Ryan
Clark, Pittsburgh Steelers. He has been able to have an NFL career despite being held out of recent games in Denver, Colorado given is SCT status. Remember, exertion at high altitudes has the potential to result in exertional sickling/sickling collapse. He has now started a foundation to search for a cure for the condition.
NCAA MANDATED SICKLE CELL TRAIT TESTING POLICY
The
National Collegiate Athletic Association (NCAA) has mandated sickle cell
testing for athletes. This requirement
is considered controversial by some based on the available (or lack thereof)
research, but my goal is not to debate the merits of the requirement, but to
help you understand it. If you’d like to
learn more about why some people believe the mandated testing policy is
unnecessary check out this
article. Testing has
been mandated for Division I athletes since 2010 and Division II since
2011. Legislation just passed that will
mandate testing at the Division III level starting this year (2013). For those of you who are concerned and do not wish to have your child tested as part of their initial college pre-participation
examination there is a waiver you can sign to opt out of the testing. Additionally, SCT positive athletes are not
restricted from participating in athletics, it simply allows the medical staff
to be more aware of the possibility of a exertional sickling and sickling
collapse. Testing is expected prior
to the start of the freshman year, or for any transfer whose status is not
known. Remember, if you have the SCT
status of your child documented at birth, additional testing prior to the entry
into college may not be necessary. Find out more information and resources from the NCAA here or contact the sports medicine staff at the college/university your child will be attending.
RESOURCES
The documents listed here are mostly statements from various professional organizations regarding SCT trait status in athletes. Some of the statements discuss recommendations for the safe sports participation and treatment in the instance of exertional sickling/sickling collapse. Others discuss the need (or suggest there is no need) for SCT screening of athletes. As always you are encouraged to take a look.
Submitted by Heather L. Clemons, MS, MBA, ATC
