Perchlorate (ClO(4)(-)) and thiocyanate (SCN(-)) are potent and nitrate (NO(3)(-)) a weak competitive inhibitor of the thyroid sodium-iodide symporter. To determine the effects of long-term, high ClO(4)(-) exposure on thyroid function, we conducted a study of 29 workers employed for at least 1.7 yr (50% over 5.9 yr) in an ammonium ClO(4)(-) production plant in Utah. Serum ClO(4)(-), SCN(-), and NO(3)(-); serum T(4), free T(4) index, total T(3), thyroglobulin (Tg), and TSH; 14-h thyroid radioactive iodine uptake (RAIU); and urine iodine (I) and ClO(4)(-) were assessed after 3 d off (Pre) and during the last of three 12-h night shifts in the plant (During) and in 12 volunteers (C) not working in the plant. Serum and urine ClO(4)(-) were not detected in C; urine ClO(4)(-) was not detected in 12 of 29 and was 272 microg/liter in 17 Pre workers; serum ClO(4)(-) was not detected in 27 of 29 Pre; and serum and urine ClO(4)(-) were markedly elevated during ClO(4)(-) exposure to 868 microg/liter and 43 mg/g creatinine, respectively. Serum SCN(-) and NO(3)(-) concentrations were similar in all groups. Thyroid RAIUs were markedly decreased in During compared with Pre (13.5 vs. 21.5%; P < 0.01, paired t) and were associated with an increase in urine I excretion (230 vs. 148 microg I/g Cr; P = 0.02, paired t) but were similar to those in the C group (14.4%). Serum TSH and Tg concentrations were normal and similar in the three groups. Serum T(4) (8.3 vs. 7.7 microg/dl), free T(4) index (2.4 vs. 2.2), and total T(3) (147 vs. 134 ng/dl) were slightly but significantly increased in the During vs. Pre workers (P < 0.01, paired t). Thyroid volumes and patterns by ultrasound were similar in the 29 workers and 12 community volunteers. In conclusion, high ClO(4)(-) absorption during three nights work exposure decreased the 14-h thyroid RAIU by 38% in ClO(4)(-) production workers compared with the RAIU after 3 d off. However, serum TSH and Tg concentrations and thyroid volume by ultrasound were not affected by ClO(4)(-), suggesting that long-term, intermittent, high exposure to ClO(4)(-) does not induce hypothyroidism or goiter in adults.

Objective: To determine first-trimester thyroid function values and associations with thyroperoxidase antibody (TPO-Ab) status, smoking, emesis, and iodine-containing multivitamin use. Methods:We collected information by interview, questionnaire, and blood draw at the initial obstetric visit in 668 pregnant women without known thyroid disease. We compared thyroidstimulating hormone (TSH), total thyroxine (T 4 ), and free T 4 index (FT 4 I) values by TPO-Ab status. Multiple regression was used to identify characteristics associated with thyroid function values. Results:The following median (range containing 95% of the data points) thyroid function test values were obtained in 585 TPO-Ab-negative women: TSH, 1.1 mIU/L (0.04-3.6); FT 4 I, 2.1 (1.5-2.9); and T 4 , 9.9 μg/dL (7.0-14.0). The following median (range containing 95% of the data points) thyroid function test values were obtained in 83 TPO-Ab-positive women: TSH, 1.8 mIU/L (0.3-6.4) (P<.001); FT 4 I, 2.0 (1.4-2.7) (P = .06); and T 4 , 9.3 μg/dL (6.8-13.0) (P = .03) (P values denote statistically significant differences between TPO-Ab-positive and negative participants). Among TPO-Ab-negative participants, TSH level was not associated with use of iodine-containing multivitamins, smoking, or race. TSH increased 0.03 mIU/L for every year of maternal age (P = . 03) and decreased by 0.3 mIU/L for every increase in parity (P<.001). T 4 decreased 0.04 μg/dL for every year of maternal age (P = .04). Mean FT 4 I was 2.05 in smokers and 2.20 in nonsmokers (P<. 01). There were no relationships between T 4 or FT 4 I and parity, race, or iodine-containing multivitamin use. Conclusion:TPO-Ab status of pregnant women should be considered when constructing trimesterspecific reference ranges because elevated serum TPO-Ab levels are associated with higher TSH and lower T 4 values.

Summary:Serum free light-chain (FLC) concentrations were measured by a sensitive nephelometric immunoassay in 66 patients with AL amyloidosis before and after treatment with highdose melphalan and autologous stem cell transplantation (HDM/SCT). At 1 year after HDM/SCT, 27 patients (41%) achieved a complete hematologic response (CR), that is, disappearance of the monoclonal gammopathy previously evident by immunofixation electrophoresis (IFE) in serum and urine and of plasma cell clonality in the bone marrow. Abnormally elevated FLC levels became normal in 27 patients (41%), and decreased by 490% in 37 (56%). Average improvements in FLC were 94% for patients who achieved a CR and 72% for those who did not (P ¼ 0.0001). However, a reduction in FLC of 490% was associated with a similar high likelihood of clinical improvement and prolonged survival, whether or not patients achieved a CR. While CR, as defined by standard criteria, is a more stringent indicator of hematologic response than are decreases in abnormally elevated FLC levels per se, these measures of hematologic response are complementary, and decreases in FLC are more readily detected early after treatment than are the changes in IFE and marrow studies required to determine CR.