Thus, this patient’s thyroid function tests have In common with many populations in tropical regions, the Marshallese have relatively high globulin levels. This increase is polyclonal, and the cause is unknown. been on the low side of normal and occasionally overtly low for many years. Transient hypothyroidism persisting for many years has been reported with chronic autoimmune thyroiditis (Takasuet al., 1992). However, the Utirik patient Serum calcium had no. detectable antithyroglobulin or antimicrosomal antibodies. While the role of radiation exposure in producing this patient’s illness is not certain, an argument can be made for relating the two. Further observation may documentthe true nature of the thyroid hormone fluctuations in this patient. Since an increase in risk of hypothyroidism might be attributed to radiation exposures as low as 20 cGy (Maxonet al., 1977), the patient clearly was at risk for developing the disorder. An endocrinological disorder that has been thought to be associated with both external and internal 1317 radiation is hyperparathyroidism (Cohen,et al., 1990; Rosen et al., 1984). A dosedependent increase in the incidence of hyperparathyroidism has also been reported in Japanese atomic bomb survivors (Fujiwara et al., 1990). In all three cited studies, parathyroid adenomas werepresent in most patients. Some of the exposed Marshallese received large radiation doses to the parathyroid gland, as well as high external doses. Furthermore, the susceptibility of Marshallese to this effect of radiation is unknown. Therefore, serum calcium levels are checked every three years. No elevated levels were detected during the 1989 survey. Other laboratory results: Appendix B also includes results of other tests that are performed on manyorall of the exposed persons. Several of these tests have been used to screen for occult malignant disease. Although there is no general marker for malignancy, the clinical justification for, and the results of, those tests are described here. Serum protein electrophoresis Multiple myelomais one of the hematological malignancies that has been determined to be inducible by radiation (Cuzick, 1981). This interpretation is strengthened by findings in Japanese atomic bomb survivors, although the effect of radiation was not detectable until about 20 years after exposure (Ichimaru et al., 1982). The production of a monoclonal protein detectable by serum electrophoresis often precedes by years the otherclinical manifestations of multiple myeloma. Although the risk of myelomais small, serum protein electrophoresis is performed on the exposed Marshallese about every three years in order to detect the early appearance of a monoclonal protein. If a monoclonal spike were to be found in a patient’s serum, it would not necessarily indicate the presence of myeloma. Conversely, the absence of such a spike does not rule out myeloma. Nevertheless, it is used as a screening test, and no monoclonal proteins were detected during the 1989 serum testing of the Marshallese sera. Serum alpha-fetoprotein Thereis a high risk of hepatocellular carcinoma in persons who remain persistently positive for hepatitis B surface antigen. The last Brookhaven medical program report discussed this disease in relation to the exposed Marshallese, for the prevalence of serologic evidence of hepatitis B infection in the Marshall Islands is very high (Adams et al., 1986). In some instances it is possible to identify hepatocellular carcinoma at an early stage by testing serum for alpha-fetoprotein. This might permit identification of the tumor at a stage when it is still resectable. Therefore, all exposed and unexposed persons who are known to the medical program to be seropositive for hepatitis B surface antigen have alpha-fetoprotein levels performed annually. Erythrocyte macrocytosis The many causes of macrocytosis include several premalignant and malignant hematologic diseases. Therefore, erythrocyte size is checked annually. During the four years covered by this report no unexplained or irreversible macrocytosis was detected in the exposed population. Those elevated levels that were found appear to have been due to nutritional deficiencies (either folic acid or vitamin B12) or chronically excessive ingestion of alcohol. 12