In an area of New Guinea where there is dietary iodine deficiency, measurements of thyroid function have been made on women of child-bearing age, several of whom were pregnant at the time. The outcome of these pregnancies, and also of those occurring in the four preceding years, were examined in relation to indices of thyroid function. More stillbirths, infant deaths and endemic cretins occurred among the offspring of women who showed biochemical evidence of iodine deficiency, without clinical evidence of hypothyroidism. This situation differs from that of untreated myxoedema or congenital hypothyroidism in women, which is usually associated with altered menstrual function, infertility or repeated abortion. Mechanisms that may account for these differences and the possible implications are discussed.

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SUMMARY Serum concentrations of triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) have been measured in subjects from an endemic goitrous area of New Guinea. An increase in TSH concentration and a decrease in T4 concentration was found in both goitrous and non‐goitrous subjects, both abnormalities being more frequent in the goitrous group. In the majority of subjects (93%) the T3 level fell within the normal range. Euthyroidism appears to be preserved in the iodine deficient state by the continued production of normal amounts of T3, the intrinsic metabolic activity of T4 being relatively unimportant.

SUMMARY The thyroidal component of the response to thyrotrophin releasing hormone (TRH) has been studied by measurement of serum triiodothyronine (T3) and thyroxine (T4). In normal subjects a significant increase in serum T3 followed intravenous administration of TRH 200 μg. A less consistent increase was detected in serum T4 concentration. Oral TRH at a dose of 40 mg caused a significant rise in serum T4 in normal subjects. The increase in T4 at 24 hr was considered to provide a convenient index of pituitary and thyroidal response. Fourteen patients with pituitary disease, of whom twelve were euthyroid, were investigated by an oral TRH test. The majority of these patients retain a normal pituitary TSH reserve though a small group can be identified in whom it is diminished. A significant correlation was obtained between the T4 and TSH response to oral TRH. It is suggested that measurement of serum concentration of thyroid hormone is of value in the assessment of the pituitary response to TRH and the integrity of the pituitary‐thyroid axis.

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