Thyroid parameters in iodine deficiency

Thyroid Plasma Clearance and Free Thyroxine Index were compared in 20 Zambians with iodine deficiency with 12 Zambians and 10 expatriates without iodine deficiency. Mean clearance was similar in the non-deficient groups (19 and 22 ml/min.) but much higher (123 ml/min.) in the deficient group. Mean Free Thyroxine Index was similar in the non-deficient groups (11.2 and 10.3) but significantly lower (8.2) in the deficient group. A relationship between iodine deficiency and low income was seen. No racial difference was apparent.