The reference range and within-person variability of thyroid stimulating hormone during the first and second trimesters of pregnancy.

OBJECTIVE: To further explore first and second trimester reference ranges for thyroid stimulating hormone (TSH) and examine within-person variability of TSH and thyroid peroxidase (TPO) antibody. SETTING: Women coming for routine prenatal care in early pregnancy agreed to participate in a trial of integrated serum screening for Down's syndrome. Two serum samples were obtained from each woman, one each in the first and second trimesters. These samples were also available for TSH and TPO measurements in the present study. METHODS: TSH and TPO antibody measurements were performed in 1126 women with ultrasound-dated pregnancies who provided serum samples in both trimesters. TSH reference ranges were established for the entire cohort and for the antibody-negative subgroup. Within-person variability of TSH measurements between trimesters was examined. RESULTS: Median TSH values are lower in the first trimester than in the second (1.00 versus 1.29 mIU/l), but 98th centile values are higher (5.20 versus 4.18 mIU/l). High correlation exists between individual women's first and second trimester TSH measurements (r=0.75, r2=0.56, p<0.001). Among 23 women with TSH values above the 98th centile in the second trimester, 17 (74%) were over the 95th centile in the first trimester. TPO antibody measurements are also highly correlated between trimesters (r=0.97, r)=0.94). CONCLUSION: Proper interpretation of TSH measurements during pregnancy requires that laboratories establish and monitor appropriate reference ranges. TSH levels show high within-person consistency between trimesters.

Risk of type 2 diabetes mellitus in young adults from a biracial community: the Bogalusa Heart Study.

BACKGROUND: Since type 2 diabetes has a strong familial component, characteristics of young adult offspring of type 2 diabetics were examined in a community sample to determine early abnormalities in black and white persons at risk. METHODS: The sample consisted of 1,338 fasting young adults (72% white, 28% black) aged 19 to 37 years from a biracial community, including those with positive parental history of type 2 diabetes (one offspring per family, n = 230) or conditions of impaired fasting glucose and type 2 diabetes (n = 22). RESULTS: Positive family history of diabetes or impaired fasting glucose and type 2 diabetes in young adults of both races were significantly associated with adverse profiles of measures of obesity and abdominal fat (body mass index, triceps and subscapular skinfolds, waist circumference, and abdominal height), systolic and diastolic blood pressures, serum total cholesterol, triglycerides, VLDL cholesterol, and HDL cholesterol, and indicators of glucose homeostasis (plasma glucose and insulin and insulin resistance index). The magnitude of the differences in obesity and abdominal fat measures and plasma glucose between individuals with and without parental diabetes was greater among blacks versus whites (P = 0. 047-0.004). Further, black offspring of both diabetics and non-diabetics had unfavorable profiles of obesity and abdominal fat measures, blood pressure, insulin, and insulin resistance index (P = 0.0001). In a multivariate analysis, adiposity measured as body mass index (P = 0.03) and plasma glucose (P = 0.003) emerged as the two independent characteristics that distinguished those with parental diabetes from those without parental disease. Insulin (P = 0.0001) and the insulin resistance index (P = 0.0001) were independently associated with conditions of impaired fasting glucose or type 2 diabetes. CONCLUSIONS: The risk factors of young adults with parental type 2 diabetes or conditions of impaired fasting glucose and type 2 diabetes can be detected early. These observations have implications for early prevention and intervention, especially for blacks.