Indian Journal of Clinical Biochemistry

, Volume 20, Issue 2, pp 35–42 | Cite as

Impact of iodine deficiency on thyroid function in pregnant African women — A possible factor in the genesis of ‘small for dates’ babies

  • Santosh C. Das
  • Uche P. Isichei
  • Aminu Z. Mohammed
  • Abraham A. Otokwula
  • Abiodun Emokpae
Article

Abstract

The effect of iodine deficiency (ID) on thyroid function in African women during pregnancy and postnatal period was examined, for which very limited information is available. Serum T4, T3, TSH, TBG, thyroxine binding capacity (TBK), free thyroxine index (FT4I=T4/TBK) and T4/TBG were determined by ELISA technique in 32 pregnant women (resident of Plateau state, Nigeria- an ID zone) through pregnancy upto term delivery, and in 5 women up to 6 weeks post delivery. Urinary iodide level was measured at delivery to determine the degree of iodine deficiency. Results were matched with a non pregnant control comprising 44 subjects. 5555 birth weights (BW) of term babies in the region were analysed to determine the prevalence of ‘small for dates’ (SFD) babies in the population. Results show that the level of serum FT4I was elevated very significantly at late gestation (P<.001) but the women were not hyperthyroid, suggesting a marked disturbance in binding of T4 with TBG during pregnancy. Five women with SFD babies were found in ‘compensated hypothyroid state’ and showed a significant depression (p<.01) in serum T4/TBG, T4, FT4I and T3 levels to a low normal range, with a concurrent significant rise (p.<.001) in TSH level (above normal range) throughout pregnancy. Incidence of SFD babies was higher (p.<.001) in ID zone (Bassa 15.2%) compared to control zone (Jos 9.8%). It is concluded that a state of maternal ‘subclinical (compensated) hypothyroidism’ during pregnancy possibly plays an important role in the aetiopathogenesis of SFD babies in Africans. A normal reference range for thyroid parameters at various stages of pregnancy in healthy African women is established for the first time.

Key Words

Africans Iodine deficiency Pregnancy Thyroid function 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Burrow, G.N. (1977) Thyroid and parathyroid function in pregnancy. In: Fuchs F, Klopper A (eds) Endocrinology of Pregnancy, ed 2. Haper and Row, New York, p. 246.Google Scholar
  2. 2.
    Sterling, K. and Hegedus, A. (1962) Measurement of free thyroxine concentration in human serum. J. Clin. Invest. 41, 1031–1040.PubMedCrossRefGoogle Scholar
  3. 3.
    Osathanondh, R., Tulchinsky, D. and Chopra, I.J. (1976) Total and free thyroxine and triiodothyronine in normal and complicated pregnancy. J. Clin. Endocrinol. Metab. 42, 98–104.PubMedGoogle Scholar
  4. 4.
    Harada, A., Hershman, J.M., Reed, A.W.et al. (1976) Comparison of thyroid stimulators and thyroid hormone concentration in the sera of pregnant women. J. Clin. Endocrinol. Metab. 48, 493–497.Google Scholar
  5. 5.
    Yamamoto, T., Amino, N., Tanizawa, O.et al. (1979) Longitudinal study of the serum thyroid hormones, chronic gonadotrophin and thyrotrophin during and after normal pregnancy. Clin. Endocrinol. (oxf.) 10, 459–462.CrossRefGoogle Scholar
  6. 6.
    Burr, W.A., Ramsden, D.B., Evans, S.E., Hogan, T. and Hoffenberg, R. (1977). Concentration of thyroxine binding globulin: value of direct assay. Brit. Med. J. 1, 485–487.PubMedGoogle Scholar
  7. 7.
    Hopton, M.R., Ashwell, K., Scott, I.V. and Harrop, J.S. (1983) Serum free thyroxine concentration and free thyroid indices in normal pregnancy. Clin. Endocrinol. 18, 431–436.CrossRefGoogle Scholar
  8. 8.
    Whitworth, A.S., Midgley, J.E.M. and Wilkins, T.A. (1982) A comparison of free T4 and the ratio of total to T4 binding globulin in serum through pregnancy. Clin. Endocrinol. 17, 307–313.CrossRefGoogle Scholar
  9. 9.
    Boss, A.M.B. and Kingatone, D. (1981) Further observation on serum free thyroxine concentration during pregnancy. Brit. Med. J. 283, 584–586.Google Scholar
  10. 10.
    Braverman, A.E., Abreau, C.M., Brock, P.et al. (1980) Measurement of serum free thyroxine by RIA in various clinical states. J. Nuc. Med. 21, 233–236.Google Scholar
  11. 11.
    Hall, R., Anderson, J., Smart, G.A. and Besser, M. (1980) Hormonal changes during pregnancy. In: Fundamentals of clinicla endocrinology, 3. ed., Pitman Medical, London, Massachusetts, p 371–381.Google Scholar
  12. 12.
    Weeks, J., Dybkjaer, L., Granile, K.et al. (1982) A longitudinal study of serum TSH and total and free iodothyronines during normal pregnancy. Acta. Endocrinol. 101, 531–537.Google Scholar
  13. 13.
    Guillaume, J., Schussler, G.C. and Goldman, J. (1985) Components of the total serum thyroid hormone concentration during pregnancy. High free thyroxine and blunted thyrotophin (TSH) response to TSH releasing hormone in the first trimester. J. Clin. Endocrinol. Metab. 60, 678–684.PubMedGoogle Scholar
  14. 14.
    Amino, N., Yamda, T., Mitsuma, T.et al. (1981) Increase in plasma thyrotrophin releasing hormone in normal human pregnancy. J. Clin. Endocrinol. Metab. 53, 1288–1291.PubMedGoogle Scholar
  15. 15.
    Skjoldebrand, I., Brundin, J., Caristorm, A. and Petterson, T. (1982) Thyroid associated components in serum during normal pregnancy. Acta. Endoctrinol. 100, 504–511.Google Scholar
  16. 16.
    Rodin, A., Mashiter, C., Quartero, G.et al. (1989) Thyroid function in normal pregnancy. J. Obstet. Gynaecol. 10, 89–94.CrossRefGoogle Scholar
  17. 17.
    Osotimehim, B. and Haffenberg, R. (1980) Serum thyroglobulin measurement in various thyroidal disorders. African J. Med. Med. Sc. 9 (3/4), 89–95.Google Scholar
  18. 18.
    Isichei, U.P., Das, S.C. and Egbuta, J.O. (1990) Central cretinism in four successive siblings. Brit. Postgrad. Med. J. 66, 751–756.Google Scholar
  19. 19.
    Isichei, U.P., Das, S.C., Banwo, A.I., Morimoto, I. and Nagataki, S. (1987) Endemic goiter in Plateau state, Nigeria. Abst IDD Newsletter. (ICCIDD/WHO/UNICEF publication) vol. 3, No. 3, p 7.Google Scholar
  20. 20.
    Isichei, U.P., Morimoto, I., Das, S.C., Egbuta, J.O., Banwo, A.I. and Nagataki, S. (1995) Endemic goiter in the Jos Plateau region of Northern Nigeria. Endocrine Journal, 42 (1), 23–29.PubMedCrossRefGoogle Scholar
  21. 21.
    Hetzel, B.S. (1988) The prevention and control of iodine deficiency disorders. United Nations Administrative committee of coordination Subcommittee on nutrition State-of-the-art series. Nutrition policy discussion paper No. 3 March, 2–25.Google Scholar
  22. 22.
    Das, S.C. and Isichei, U.P. (1993) The fetomaternal thyroid function interrelationships in an iodine deficient region in Africa- the role of T3 in possible fetal defence. Acta. Endocrinol. 128, 116–119.PubMedGoogle Scholar
  23. 23.
    Das, S.C., Isichei, U.P., Egbuta, J.C. and Banwo, A.I. (1989) Cations and anions in drinking water as putative contributory factors to endemic goiter in Plateau State, Nigeria. Trop. Geogr. Med. 4, 346–352.Google Scholar
  24. 24.
    Morimoto, I., Isichei, U.P., Das, S.C., Banwo, A.I., Egbuta, J.O. and Nagataki, S. (1987) Urinary iodide and thiocynate concentration among school children in endemic goiter area of Plateau state, Nigeria. Proc Nigeria/Japan Joint Conf. G-6, 78–81.Google Scholar
  25. 25.
    Das, S.C., Isichei, U.P. and Egbuta, J.O. (1989) Variations in biochemical indices of coronary risk status in endemic goitre. Asean J. Clin. Sc. 9, 85–98.Google Scholar
  26. 26.
    Marc, J.N.C. Keiree. (1984) Epidemiology and aetiology of the growth retarded baby. In: Clinics in Obstet Gynaecol “Small Baby”. Howie, P.W. and Patel, N.B. (eds.) W.B. Saunders Company. London. Philadelphia. Toronto. vol III, No. 2, 415–435.Google Scholar
  27. 27.
    Methodology manuals (1986). Boehringer Mannheim Immunodiagnostics. Mannheim, Germany.Google Scholar
  28. 28.
    Thilly, C.H., Delange, F., Lagasse, R.et al. (1978) Fetal hypothyroidism and maternal thyroid status in severe endemic goiter. J. Clin. Endocrinol. Metab. 47, 354–360.PubMedCrossRefGoogle Scholar
  29. 29.
    Chan, B.Y. and Swaminathan, R. (1988) Serum thyrotrophin concentration measured by sensitive assays in normal pregnancy. Brit. J. Obstet. Gynaecol. 95, 1332–1336.Google Scholar
  30. 30.
    Smith, S.C.H. and Bold, A.M. (1983) Interpretation of invitro thyroid function tests during pregnancy. Brit. J. Obstet. Gynaecol. 90, 532–534.Google Scholar
  31. 31.
    Wright, E.A. (1989) Birth weight of infants in Jos, Nigeria. West Afri. J. Med. 8, 166–170.Google Scholar
  32. 32.
    Delong, R. (1987) Neurological involvement in iodine deficiency disorders, In: Hetzel, B.S., Dunn, J.T. and Stanbury, J.B. (eds). The prevention and control of iodine deficiency disorders. Amsterdam, Elsevier, Biomedical Division, 49–63.Google Scholar

Copyright information

© Association of Clinical Biochemists of India 2005

Authors and Affiliations

  • Santosh C. Das
    • 1
  • Uche P. Isichei
    • 2
  • Aminu Z. Mohammed
    • 3
  • Abraham A. Otokwula
    • 2
  • Abiodun Emokpae
    • 1
  1. 1.Department of Chemical PathologyAminu Kano Teaching HospitalKanoNigeria
  2. 2.Department of Chemical PathologyUniversity of JosJosNigeria
  3. 3.Department of PathologyAminu Kano Teaching HospitalKanoNigeria

Personalised recommendations