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Smit et al., Amsterdam, The Netherlands, studied motor nerve conduction
velocity (MNCV) in 200 preterm infants (<30 weeks gestational age) in
a placebo-controlled randomized, double- blind trial of T4 supplementation
(8 µg/kg birthweight per day). MNCV was measured in ulnar and posterior
tibial nerve. They found that at 2 weeks of age a trend was found towards
an increased ulnar MNCV (p="0.06)" in the T4 group, but no effect in the
posterior tibial MNCV. At 40 and 66 weeks postmenstrual age no effect was
seen in either measurement. The conclusion is, that daily T4 supplem entation
in infants or < 30 weeks gestational age has no clear effect on MNCV.
Premawardhana et al., Cardiff, UK, studied clinical and biochemical thyroid function and ultrasound morphology in 155 women, 7-10 years after recruitment to a study concerning postpartum thyroid dysfunction (PPTD). Fourty-two (27.1%) thyroid peroxidase antibody (TPO- ab) negative women served as control. Of the 113 TPO-ab positive women, 52 (56%) had biochemical PPTD at recruitment. All TPO-ab negative subjects had normal thyroid function at review, but 24.8% of TPO-ab >positive women had thyroid dysfunction (mostly hypothyroidism). Hypothyroidism occurred in 44.2% of women who had previously PPTD, whereas it occurred only in 8.1% of women who never had PPTD. Sixteen patients (14.2%) were hypothyroid at 9 months postpartum and required permanent T4 therapy. Of the 97 women who were TPO-ab positive but euthyroid postpartum, 28% had thyroid dysfunction at review 7-10 years later. Fifty- seven % of TPO-ab positive women had abnormal ultrasound morphology at review. The incidence of echographic abnormalities in PPTD patients was significantly higher at the time of the original diagnosis than at follow-up and also higher 7-10 years later than in PPTD negative women. There was no correlation between TPO-ab levels and the degree of morphological derangement at the time of review. From the results it is concluded that women with PPTD require more intensive follow-up than those who were anti TPO-ab positive but PPTD negative. Momotani et al., Tokyo, Japan, investigated 77 pregnant women with hyperthyroid Graves' disease, who's serum FT4 levels were kept within the normal range by methimazole or PTU. Maternal FT3 levels were above normal in 39% of women, but no women manifested pregnancy complications or augmentation of thyroid toxic symptoms following delivery. In the neonates FT4 was below normal in 6.5%, and TSH above normal in 16.9% at birth. These abnormalities disappeared within 4 days after birth. To the opinion of the authors, the duration of transient hypothyroidism in these cases is too short to cause intellectual retardation. The authors recommend to treat women with methimazole or PTU, when pregnant, such that FT4 is in the normal range. (Comment: Usually it is suggested to keep the FT4 in the high normal range in pregnant women with hyperthyroidism. As maternal T4 is being transferred to the fetus, a low maternal serum T4 should be avoided to prevent possible damage to the central nervous system of the offspring.) |
