endocrine (nondiabetes) disorders,” however, was slightly higher among the deployed (prevalence ratio 1.24, 95% CI 1.11-1.39), but these disorders were not specified.

Also in the context of the National Health Survey of Gulf War Veterans Study, the frequency of self-reported diabetes was compared among Gulf War veterans according to their potential exposure to the Khamisiyah demolition (Page et al., 2005). Prevalence of diabetes (OR 0.92, 95% CI 0.57-1.48) or other endocrine disorders (OR 0.92, 95% CI 0.65-1.30) was similar in those potentially exposed and unexposed.

In a mailed survey conducted in 1997, Canadian male Gulf War veterans (n = 2924) reported a prevalence of diabetes similar to that for nondeployed male veterans (n = 3241) (0.6% vs 0.4% in those aged 20-44 years and 2.0% vs 3.8% in those aged 45-64 years) (Goss Gilroy, 1998). Another study conducted in New England between 1994 and 1996 included 141 Gulf War veterans and 46 veterans deployed to Germany. The prevalence of self-reported diabetes was comparable in the two groups (2% in Gulf War veterans vs 0% in Germany-deployed veterans) (Proctor et al., 2001a).

Smith et al. (2006) compared hospitalizations in Gulf War deployed veterans with veterans deployed in the Persian Gulf after the war (Southwest Asia veterans) and in Bosnia (details on this study are provided in the section on hospitalizations for endocrine disorders). This study is considered secondary for diabetes, since diabetes discharge codes have low sensitivity and specificity for the diagnosis of diabetes (see, for example, Kieszak et al., 1999). The incidence of diabetes was similar among Gulf War veterans and Southwest Asia veterans (rate ratio 0.95, 95% CI 0.69-1.30, comparing Southwest Asia veterans to Gulf War veterans), but lower among veterans in Bosnia (rate ratio 0.54, 95% CI 0.29-1.00). This study was limited by including only hospitalizations occurring in DoD hospitals among active-duty personnel.

Thyroid Disease

The most frequent disorders of the thyroid gland are hypothyroidism and hyperthyroidism, characterized respectively by low or high levels of thyroid hormones. Many different causes can lead to these disorders, including autoimmune diseases, infections, malnutrition, exposure to some drugs or toxins, or neoplasias. Thyroid disease was not specifically studied in Volume 4.

Updated and Supplemental Literature
Primary Studies

Thyroid disease was included as an outcome in the study by Eisen and colleagues (2005). The study has been mentioned above under diabetes. Briefly, it evaluated 1061 Gulf War deployed and 1128 nondeployed veterans from those participating in the National Health Survey of Gulf War Era Veterans and Their Families. Based on physical examinations, the prevalence of hypothyroidism (defined as having an untreated thyroid-stimulating hormone level of 10.0 mU/mL or greater, or taking medication for hypothyroidism) and hyperthyroidism (defined as having an untreated thyroid-stimulating hormone level less than 0.1 mU/mL, or taking medication for hyperthyroidism) in deployed veterans were 1.6% and 0.3%, respectively. The corresponding prevalences in nondeployed were 1.2% and 0.1% (OR of hypothyroidism: 1.70, 95% CI 0.75-3.87; OR of hyperthyroidism 4.86, 95% CI 0.68-34.58). This study had a low participation rate, which limits the reliability of its results.

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