Onefinding that may beof clinical value is Hypothyroidism, which.is sometimes associated with elevated serum cholesterol levels, may be a risk factor for coronary heart disease (Becker 1985). To determine whether an abnormality in serum lipids may have evolved in the exposed groups as an indirect consequence of radiation injury or thyroid surgery, serum levels of cholesterol, triglyceride, and highdensity lipoprotein were obtained in 1984. The results of an analysis by group are presented in Table 1. There was no significant difference between the mean serum cholesterol levels of the exposed Rongelap or Utirik groups and the unexposed. Since almost all the Rongelap exposed are receiving thyroid hormone in suppressivedoses, itis unknown whetheror not some of the cholesterol] levels would be elevated if thyroxin were not being taken. At this point, then, questions concerning their risk of thyroidrelated hypercholesterolemia are moot. However, an analysis of Rongelap exposed and comparison group cholesterol levels in 1957 revealed the latter to be the higher by 17% (Conard et al. 1958). Analysis of serum cholesterol in persons with known thyroid hypofunction in 1984, as documented by an elevated TSH, and in persons who have had thyroid surgery revealed no values lying outside a normal range established by testing the comparison population (based on two standard deviations from the mean). the relatively low level of high-density lipo- protein foundin all three exposure groups. Since this lipid category, as an independent risk factor, shows an inverse association with coronary heart disease, the low levels found may indicate a propensity for the disorder among Marshallese. However, confirmation of the finding is required to rule out technical prob- lems associated with transport and storage of serum specimens. Thyroid Neoplasia The Marshall Islands medical program is most fortunate to have the continued support of four eminent consultant pathologists who review the histologic sections of all thyroid nodules removed at surgery.* The same individuals were amongthe groupof pathologists who, in 1981, reviewed all thyroid sections obtained throughout the history of the program. This has provided consistent year-to-year diagnostic categories of thyroid neoplasia. In 1983-84, six persons underwent thyroid surgery at Cleveland Metropolitan Hospital * Dr. L.V. Ackerman, Health Sciences Center, SUNY, Stony Brook, NY; Dr. W.A. Meissner, New England Deaconess Hospital Boston, MA; Dr. A.L. Vickery, Massachusetts General Hospital, Boston, MA; Dr. L.B. Woolner, Mayo Clinic, Rochester, MN. Table 4 Lipid Profiles by Radiation Exposure Group n Cholesterol (mg/dl) Triglycerides (mg/dl) (male) 21 154 + 27* 147 + 168 36 +9 (female) 29 170 + 32 121 +67 34 +11 42 177 +37 222 +139 30 +5 49 187 +35 153 + 102 33 +5 34 172 + 27 173 +95 29 +6 60 179 + 36 1438 +143 30 28 Exposure Category High-density Lipoprotein (mg/dl) Rongelap Utirik (male) (female) Comparison (male) (female) * One Standard deviation. 11