Sports Medicine: Just the Facts

196 SECTION 3 • MEDICAL PROBLEMS IN THE ATHLETE

ETIOLOGIES OF ERYTHROCYTOSIS

• Pseudoerythrocytosis:Phlebotomy when patient in a
  dehydrated state.


• Polycythemia vera: A myeloproliferative disorder
  involving trilineage marrow hyperplasia. RBC mass
  increase associated with leukocytosis and thrombocy-
  tosis. Erythropoeitin levels are low with markedly ele-
  vated Hct. These patients require regular phlebotomy
  to prevent a hyperviscosity state (Levine, 1999).


• Secondary erythrocytosis:results from intrinsic ele-
  vated erythropoietin or excess erythrocyte production
  (Means, 1999).
  
  
  1. Hypoxic stress
  
  
  2. Endogenous conditions of excessive erythropoietin
     production
  
  
  3. Endogenous conditions of isolated excess erythro-
     cyte production
  
  
  
  


• Blood doping
  
  
  1. Transfusion (Simon, 1994)
     2.Exogenous erythropoietin (e.g., rEPO)-character-
     ized by elevated RBC and erythropoietin levels with
     normal WBC and platelet counts (Means, 1999;
     Simon, 1994).
  
  
  
  

WBC LINE ABNORMALITIES

• Strenuous or prolonged vigorous exercise may pro-
  duce acute profound perturbations of WBC popula-
  tions. This effect, however, resolves with rest and is
  not typically associated with persistent abnormalities
  of white cell lines. Various drugs may either elevate or
  depress WBC production, as may infection. Persistent
  leukopenia may be indicative of human immunodefi-
  ciency virus infection or marrow disorders. Some
  populations (e.g., Black males) may manifest a mild
  neutropenia that is nonpathologic (Jandl, 1996).


• If blood work indicates a pathologic alteration of the
  WBC population, examination should include a thorough
  assessment of lymphatic and hematologic systems with
  investigation for infectious, toxic, or oncologic causes.


• Readily treatable etiologies such as infection are
  addressed as indicated. Referral to a hematologist for
  bone marrow assessment may be necessary, particularly
  if there is profound leukopenia, leukocytosis, or distur-
  bances of other cell lines suggestive of malignancy
  (Tenglin, 1999).

ABNORMALITIES OF PLATELETS
AND COAGULATION

• The effects of exercise, particularly endurance activi-
  ties, seem to have a net neutral effect on platelets and
  coagulation. Athletes manifesting petechiae, unusual

bruising or bleeding problems should undergo prompt

investigation for causes of these. Long-standing history

of mild bleeding or bruising problems may indicate

Von Willebrand’s disease or mild factor VIII or IX defi-

ciency. Certain drugs, toxins, autoimmune disorders,

infections, malignancies, and other conditions that trig-

ger disseminated intravascular coagulation (DIC) may

produce thrombocytopenia ranging from mild to severe

(Tenglin, 1999). Diets deficient in green vegetables may

manifest coagulopathy because of impairment of vita-

min K dependent factors (Tenglin, 1999).

•Evaluation of platelet and coagulation disorders focuses

on identification of causative conditions as listed above.

Laboratory assessment should start with a CBC with

peripheral smear looking for abnormalities in all hema-

tologic cell lines. Coagulation studies (prothrombin

time, PT; partial thromboplastin time, PTT; and inter-

national normalized ratio, INR) should be conducted as

well. If the clinical picture suggests DIC (low platelets,

fragmented RBCs, and prolonged coagulation times)

confirmatory testing to include fibrinogen, fibrin split

products, and D-dimer should be added (Tenglin, 1999).

• Thrombocytosis is often a transient condition, typi-
  cally a manifestation of an acute response to physio-
  logic stress. Transient isolated thrombocytosis is rarely
  of significance. Persistent thrombocytosis should
  prompt investigation for infection, inflammatory disor-
  ders, malignancies, or other hyperproliferative disorders
  (e.g., polycythemia vera, myeloproliferative diseases)
  (Levine, 1999).

OTHER DISORDERS CAUSING

ANEMIA/CELL LINE ABNORMALITIES

• Anemia and other cell line abnormalities may result
  from several other conditions or as a consequence var-
  ious disease processes. These may manifest in the
  form of accelerated cell destruction or hemolysis, or
  through impaired erythropoiesis. Details regarding
  diagnosis and evaluation of these conditions may be
  found in hematology reference books (Abramson and
  Aramson, 1999; Lee, 1999d).

SPECIAL CONSIDERATIONS—

EXERTIONAL RHABOMYOLYSIS

AND MYOGLOBINURIA

EXERTIONAL RHABDOMYOLYSIS

• Rhabdomyolysis is a condition of skeletal muscle
  breakdown with release of myocyte contents into the
  circulation. Exertional rhabdomyolysisis the term