Effect of environmental iodine deficiency (EID) on foetal growth in Nigeria.

BACKGROUND & OBJECTIVES: There is scarcity of information on impact of iodine deficiency on growth and development of newborns, both pre-term and term babies. The present study was carried out to see the impact of iodine deficiency (ID) on the intrauterine foetal growth and development in terms of birth weight (BW) in an African population living in an iodine deficient zone. METHODS: The maternal and cord serum thyroid parameters at term delivery (38-40 wk of gestation) were measured and correlated with the birth weights of the corresponding newborns, and the results compared between those assessed in an ID zone (Jengere region of Bassa district, Plateau State, Nigeria) and with that of non ID (Control) zone, Jos, the State capital. RESULTS: The level of maternal and neonatal thyroid function were significantly reduced in the group with low birth weights (<2.5 kg) as compared to the level seen in normal birth weights category in both control (Jos) and ID (Jengere) regions. Both in non ID and ID regions the maternal serum thyroxine (T4), thyroxine binding globulin (TBG) and free thyroxine index (FT4I) were positively correlated (P<0.005) with BW of term babies while thyroid stimulating hormone (TSH) (P<0.005) and thyroxine binding capacity (TBK) (P<0.05) showed negative correlation. Maternal T3 and T3/T4 ratio did not show any correlation with BW in Jos, while in the ID region of Bassa the BW showed a positive correlation (P<0.005) with the maternal serum T3 and T3/T4 ratio. Cord serum analysis of the term babies revealed that the BW was positively correlated with its T4, triiodothyronine (T3), TBG, FT4I and T4/TBG ratio (Jos only) (P<0.005) in both ID region of Bassa and non ID control zone of Jos. Cord serum TSH and TBK showed negative correlation (P<0.005) with BW. Thyrotrophin releasing hormone (TRH) stimulation test revealed that mothers with small for date (SFD) babies at term were more hypothyroid compared to the level of thyroid function seen in the women delivering normal babies. INTERPRETATION & CONCLUSION: Maternal thyroid hormone plays a significant role in the intrauterine foetal growth and development, and the smaller babies and their corresponding mothers, in an ID affected area are functionally sub-thyroid in greater proportion due to prevailing long standing environmental iodine deficiency (EID). Maternal T3 is an important factor in the defence of foetus in ID regions.

Serum and thyroid tissue lipids in patients with thyroid tumors in euthyroidism.

Plasma lipids of 24 euthyroid subjects with thyroid adenoma and non-toxic primary differentiated thyroid carcinoma (papillary and follicular types) were assessed and compared with a similar investigation conducted on 20 normal subjects. A parallel study with thyroid tumor tissues examined the lipid changes which occurred in the same group of patients. These were compared with the picture seen in 5 normal thyroids. The investigations examined the changes in total lipids; total, free and esterified cholesterol; total phospholipids; lecithin; cephalin and sphingomyelin; triglycerides and free fatty acids in both serum and thyroid tissue. Compared with normal subjects, the serum lipids were almost identical except for the concentration of free fatty acids which showed significantly lower values in the group with neoplastic changes. Tissue analysis of the cancerous thyroid however revealed a marked rise in virtually all lipid fractions but the cholesterol seemed to dominate the picture. The differential studies of total phospholipids for thyroid tissue membrane lipids further revealed a significant increase in the lecithin and sphingomyelin components of total phospholipids as well as the esterified cholesterol fraction in thyroid carcinoma. The changes in thyrophospholipids were more marked in females normal thyroids than males. An attempt has been made through evaluation of the results derived from differential lipid studies to elucidate the role of some of the various fractions determined and the possible effect of the changes described on thyroid hormone metabolism.