RESUMEN
CONTEXT: A lower free T(4) (fT4), within the euthyroid range, has been shown in adults to associate with an adverse metabolic phenotype. Thyroid physiology changes significantly during gestation and affects maternal and fetal well-being. OBJECTIVE: The aim of the study was to test the hypothesis that a lower serum fT4 in healthy euthyroid pregnant women is related to a less favorable metabolic phenotype and to fetal or placental weight. DESIGN, SETTING, PATIENTS, AND OUTCOME MEASURES: We examined associations of thyroid function tests (TSH and fT4) and the free T(3) (fT3)-to-fT4 ratio (as a proxy of deiodinase activity) with a metabolic profile [preload and postload glucose, glycosylated hemoglobin (HbA1c), high molecular-weight (HMW)-adiponectin, homeostasis model of assessment for insulin resistance (HOMA-IR), and serum lipids] in 321 healthy pregnant women. All women were euthyroid and had negative anti-thyroid peroxidase antibodies. None received thyroid hormone replacement. Blood tests were performed in women between 24 and 28 wk gestation. Placentas and newborns were weighed at birth. RESULTS: Circulating TSH did not relate to metabolic parameters, but decreasing fT4 and increasing fT3-to-fT4 ratio associated with a less favorable metabolic phenotype, as judged by higher postload glucose, HbA1c, fasting insulin, HOMA-IR, and triglycerides, and by a lower HMW-adiponectinemia (all P ≤ 0.005). In multiple regression analyses, fT4 was independently associated with HbA1c (ß = -0.135; P = 0.038), HMW-adiponectin (ß = 0.218; P < 0.001), and placental weight (ß = -0.185; P < 0.005), whereas the fT3-to-fT4 ratio was independently associated with maternal body mass index (ß = 0.265; P < 0.001), HMW-adiponectinemia (ß = -0.237; P < 0.002), HOMA-IR (ß = 0.194; P = 0.014), and placental weight (ß = 0.174; P = 0.020). CONCLUSION: In pregnant women without a history of thyroid dysfunction, lower concentrations of fT4 and a higher conversion of fT4 to fT3, as inferred by changes in the fT3-to-fT4 ratio, were found to be associated with a less favorable metabolic phenotype and with more placental growth.
Asunto(s)
Embarazo/metabolismo , Glándula Tiroides/metabolismo , Tiroxina/sangre , Salud de la Mujer , Adulto , Estudios Transversales , Femenino , Humanos , Resistencia a la Insulina , Fenotipo , Pruebas de Función de la Tiroides , Tirotropina/sangre , Triyodotironina/sangreRESUMEN
Prenatal growth is known to affect glomerular function in adult life. It is unknown, however, whether this association is also present in children. In a cross-sectional study, we examined whether birth weight (BW) is associated with serum creatinine (measured by an improved Jaffe method) and GFR (estimated by the Haycock-Schwartz formula; eGFR) in 73 apparently healthy school-age children (35 boys and 38 girls; age 9.5 +/- 0.4 yr). All children were born after singleton term pregnancies (gestational age 39.6 +/- 0.2 wk) with normal BW (3.2 +/- 0.04 kg). A significant decrease in serum creatinine and increase in the eGFR was evident by tertiles of BW-SD score (SDS) (p = 0.001 and p < 0.0001). eGFR was correlated with BW-SDS (r = 0.45; p < 0.0001), so that each unit increase in BW-SDS was associated with an increase in eGFR of 10 (95% CI 5-14) ml/min per 1.73 m. In summary, estimates of glomerular function are in apparently healthy school-age children influenced by size at birth. These findings suggest early effects for the prenatal programming of renal function in humans.