title: The effect of long-term low-dose lead exposure on thyroid function in adolescents.
abstract: This study investigated blood lead (Pb-B) levels and Pb-B effects on thyroid functions in long-term low-level-lead-exposed male adolescents who work as auto repairers. Pb-B and ALAD index (logarithm of activated delta-aminolaevulinic acid dehydratase/nonactivated delta-aminolaevulinic acid dehydratase) were measured as indicators of exposure to lead. Thyroid function tests including free thyroxine (FT4), free triiodothyronine (FT3), and thyrotrophin (TSH) were conducted and thyroid ultrasounds were performed in 42 lead-exposed adolescents and 55 healthy control subjects. Mean Pb-B levels and ALAD index were found significantly higher in the study group than in the normal control group (7.3+/-2.92 microg/dl vs. 2.08+/-1.24 microg/dl, P < 0.001 and 0.44+/-0.26 vs. 0.29+/-0.23, P < 0.05, respectively). FT4 levels were found significantly lower in the study group (1.02+/-0.18 mI/mL and 1.12+/-0.14 mIU/mL, P < 0.05). No subject in the control group had an abnormal FT4 level, but FT4 levels were found under normal limits in 11 subjects (26%) in the study group. FT3 and TSH levels in the study and control groups did not differ (P > 0.05). Thyroid volumes in the study and control groups did not exhibit any significant differences (P > 0.05). Pb-B was found to be negatively correlated to FT4 levels (r = -0.20, P = 0.044). This study revealed that long-term low-level lead exposure may lead to reduced FT4 level without significant changes in TSH and T3 levels in adolescents even at low Pb-B levels.
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Suleyman Demirel University, Merkez 32040, Isparta, Turkey. bdundar@med.sdu.edu.tr
authors.forename: Bumin
authors.initials: B
authors.lastname: Dundar
authors.forename: Faruk
authors.initials: F
authors.lastname: Oktem
authors.forename: Meltem Koyuncu
authors.initials: MK
authors.lastname: Arslan
authors.forename: Namik
authors.initials: N
authors.lastname: Delibas
authors.forename: Bahattin
authors.initials: B
authors.lastname: Baykal
authors.forename: Cağatay
authors.initials: C
authors.lastname: Arslan
authors.forename: Mustafa
authors.initials: M
authors.lastname: Gultepe
authors.forename: Inci Ergurhan
authors.initials: IE
authors.lastname: Ilhan
mesh_terms: D000293:Adolescent; D001336:Automobiles; D006801:Humans; D007854:Lead / Q000097:blood / Q000633:toxicity*; D008297:Male; D016273:Occupational Exposure; D000623:Porphobilinogen Synthase / Q000097:blood; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood
chemical_list: D014284:Triiodothyronine; D007854:Lead; D013972:Thyrotropin; D000623:Porphobilinogen Synthase; D013974:Thyroxine