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The Association between Hematological and Inflammatory Factors and Stress Fractures among Female Military Recruits

MERKEL, DRORIT1; MORAN, DANIEL S.2,3; YANOVICH, RAN2,3; EVANS, RACHEL K.4; FINESTONE, AHARON S.5; CONSTANTINI, NAAMA6; ISRAELI, ERAN7

Medicine & Science in Sports & Exercise: November 2008 - Volume 40 - Issue 11 - pp S691-S697
doi: 10.1249/MSS.0b013e318189560c
November Supplement

Background: With the growing number of females accepted for combat-related military duties in the Israeli Defense Forces, their special needs should be addressed. Previous studies on females in combat training have found a high prevalence of iron deficiency at recruitment as well as an increased rate of stress fractures (SF) and overuse injuries during training when compared with males. The aim of this study was to assess the correlation between hematological and inflammatory variables and SF occurrence among military recruits during basic training.

Methods: Three gender-integrated light infantry units were followed prospectively. Female recruits inducted for medic and dental assistants' courses were followed for comparison. Hemoglobin, iron, transferrin, ferritin, C-reactive protein, and interleukin-6 levels were measured for all participants at recruitment and at 2 and 4 months of training. SF were diagnosed radiographically or scintigraphically according to the Israeli Defense Forces protocol.

Results: A total of 438 subjects were recruited (female combatants = 227, male combatants = 83, noncombatant females = 128). At induction, 18% of female combatants had anemia compared with 8% of males and 19% of noncombatants. Iron deficiency was noted in 40%, 6%, and 38%, respectively. There were no clinically significant changes during training. Twelve percent of female combatants developed SF, whereas none occurred among male combatants or noncombatants. Subjects sustaining an SF had significantly lower levels of serum iron and iron saturation.

Conclusions: A high incidence of anemia as well as iron deficiency was found in this young asymptomatic cohort, with no significant change during training. The lower level of iron in female combatants sustaining SF warrants further investigation.

1Department of Hematology, Sheba Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, ISRAEL; 2Heller Institute of Medical Research, Sheba Medical Center, Tel Hashomer, ISRAEL; 3Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, ISRAEL; 4US Army Research Institute of Environmental Medicine, Natick, MA; 5Department of Orthopaedic Surgery, Assaf HaRofeh Medical Center, Zerrifin, ISRAEL; 6Department of Orthopedic Surgery, Hadassah Hebrew University Medical Center, Jerusalem, ISRAEL; and 7Division of Medicine, Department of Gastroenterology, Hebrew University-Hadassah Medical Center, Jerusalem, ISRAEL

Address for correspondence: Drorit Merkel, M.D., Department of Hematology, Sheba Medical Center, Tel Hashomer 52621, Israel; E-mail: mdrorit@hotmail.com.

©2008The American College of Sports Medicine