194 SECTION 3 • MEDICAL PROBLEMS IN THE ATHLETE
plasma volume; however, plasma volume expansion
typically exceeds the increase in red cell mass causing
a slight reduction in Hgb and Hct in the resting state.
This condition, common in athletes, is not a true
anemia but rather a physiologic adaptation that pro-
motes increased cardiac output, enhanced oxygen
delivery to tissues, and protects against hyperviscosity
(Selby and Eichner, 1994; Eichner, 1992; 1997).- Plasma volume can decrease 5 to 20% with endurance
exercise (sweat losses and intravascular fluid shifts)
(Selby and Eichner, 1994). - Conditioned endurance athletes tend to have greater
reductions as a result of greater sweat losses. - Hgb values typically run 0.5 g/dL lower for athletes
regularly pursuing moderate intensity training and
1.0 g/dL lower for elite level athletes (Eichner, 1997). - Diagnosis may be confirmed by
- Testing the athlete after several days rest from
training as the hemodilution of conditioning
reverses within days of terminating endurance
level training (Selby and Eichner, 1994). - Inferred from laboratory testing yielding:
a. Normal RBC indices and red cell distribution
width (RDW) on complete blood count(CBC).
b. Normal reticulocyte count.
c. Normal serum ferritin level (normal ferritin
levels in athletes may be as low as 12 μg/L,
particularly with high intensity training)
(Cook, 1994).
- Testing the athlete after several days rest from
IRON DEFICIENCY ANEMIA
- Deficiency of iron in the body is the most common
cause of trueanemia in the athlete as in the nonathlete
(Eichner, 1992; 1997). It may arise from inadequate
dietary intake, excess losses through blood loss, or a
combination of the both.
a.Occurs more often in female athletes mostly
because of menstrual losses coupled with inade-
quate consumption of meat or other sources of iron
(Cook, 1994; Eichner, 1992).
b.Laboratory testing reveals a low Hgb and Hct with
low mean corpuscular volume (MCV) and mean
corpuscular hemoglobin(MCH).
c.RDW is increased, unless iron deficiency is
chronic.
d. Peripheral smear reveals hypochromic microcytic
cells with a low to normal reticulocyte count.
e. Serum ferritin levels are low (< 12 μg/L) and better
reflect total body iron content as serum iron levels
are inconsistent.
f. Total iron binding capacity(TIBC) tends to be ele-
vated.
g. Transferrin saturation (Serum iron ×100/TIBC)
tends to be low (particularly <16%) (Lee, 1999b;
1999c).- In evaluation of iron deficiency anemia, it is imperative
to determine the cause of the deficiency in order to best
effect therapy and avoid overlooking potentially serious
conditions. Iron replacement should continue until 6 to
12 months after anemia has resolved (Selby, 1991).
ANEMIA FROM BLOOD LOSS- Acute bleeding as well as significant hemolysis and
cumulative insidious blood loss may cause anemia.
Acute hemorrhage is typically obvious from history or
examination findings of gross blood, melena, or hypo-
volemia. Bleeding contained within tissues or body
cavity may be less obvious, particularly in the retroperi-
toneal space. Characteristics of rapid blood loss:
a. Hgb and Hct (both concentration values) are ini-
tiallynormal in the absence of any fluid adminis-
tration (Lee, 1999a; 1999b).
b.Platelet counts initiallydrop with hemorrhage but
become elevated within 1 h if no hemorrhage stops
(Lee, 1999a; 1999b).
c. Hgb and Hct values decline over the ensuing days
with plasma expansion from endogenous reservoirs
(Lee, 1999a; 1999b).
d. RBC indices are initially normal. After 3 to 5 days
MCV and RDW increase because of reticulocyte
response (Lee, 1999a; 1999b).
e. Bilirubin levels are normal unless bleeding is inter-
nal. Similar to hemolysis, internal bleeding causes
a rise in unconjugated bilirubin and lactate dehy-
drogenase (LDH), but without evidence of hemol-
ysis on peripheral smear (Lee, 1999a; 1999b). - If blood loss is slow and insidious as in gastrointesti-
nal(GI) bleeding or menstrual blood loss in women,
anemia may not manifest until iron stores are depleted.
This situation may be revealed by a reticulocytosis
with concomitant increase in RDW well before iron
stores are depleted and MCV becomes low. - Gastrointestinal blood loss:GI bleeding is a very
common and often serious cause of anemia. It may
arise from peptic ulcer disease, vascular anomalies,
inflammatory bowel diseases, ischemic syndromes,
infection, diverticuli, or tumors. Thus a stool occult
blood test is indicated in any anemia evaluation
(Little, 1999). Athletes often manifest GI bleeding in
marathons and similar endurance events. - Features of exercise associated GI Bleeding:
1.Occurs exclusively with prolonged endurance
events and is low grade (Selby and Eichner, 1994;
Cook, 1994; Selby, 1991).