Hypothyroidism: an early sign of vitamin A deficiency in chickens

J Nutr. 1984 Sep;114(9):1733-6. doi: 10.1093/jn/114.9.1733.


The effect of a marginal vitamin A deficiency on thyroid function was investigated in chicks gaining weight. This study examined the hypothesis that hypothyroidism is one of the earliest manifestations of hypovitaminosis A in chicks. Day-old Leghorn cockerels were fed vitamin A-adequate and deficient diets. Blood vitamin A levels were reduced in the deficient chicks by 3 weeks of age. Body weight gains were less in the 5-, 6-, 7- and 8-week-old A-deficient chicks than in controls. Compared to controls, vitamin A-deficient chicks were characterized by thyroid follicle hypertrophy by 4 weeks, heavier thyroids as a percent of body weight at 5 weeks, less serum thyroxine (T4) at 7 weeks and lower serum triiodothyronine (T3) and T4 at 8 weeks. These results indicate that one of the earliest signs of vitamin A deficiency in chicks is hypothyroidism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chickens / blood*
  • Hypothyroidism / blood
  • Hypothyroidism / etiology
  • Hypothyroidism / veterinary*
  • Male
  • Organ Size
  • Poultry Diseases / blood*
  • Thyroid Gland / pathology
  • Thyroxine / blood
  • Triiodothyronine / blood
  • Vitamin A Deficiency / blood
  • Vitamin A Deficiency / complications
  • Vitamin A Deficiency / veterinary*


  • Triiodothyronine
  • Thyroxine