Y. Hidaka et al., PREDICTION OF POSTPARTUM GRAVES THYROTOXICOSIS BY MEASUREMENT OF THYROID-STIMULATING ANTIBODY IN EARLY-PREGNANCY, Clinical endocrinology, 41(1), 1994, pp. 15-20
OBJECTIVE Autoimmune thyroid diseases often occur after delivery. Howe
ver, it has been difficult to predict who will develop Graves' thyroto
xicosis after delivery. We tried to establish a systematic method for
predicting postpartum onset of Graves' thyrotoxicosis. DESIGN We follo
wed up the pregnant women with antithyroid microsomal antibody (MCAb)
from early pregnancy to the post-partum period and analysed the relati
on between the activities of thyroid stimulating antibodies (TSAb) in
early pregnancy and post-partum occurrence of Graves' disease. PATIENT
S Seventy-one women with positive MCAb in early pregnancy were studied
. They were randomly selected from 262 MCAb-positive subjects found in
3405 consecutive early pregnant women who attended our maternity clin
ic during the last ten years. MEASUREMENTS MCAb was measured with a co
mmercially available agglutination kit. For 71 MCAb-positive subjects,
TSH-binding inhibitory immunoglobulin (TBII) and TSAb were measured i
n early pregnancy, and serially until 6 months after delivery for the
subjects with either positive TBII or TSAb. Thyroid function and goitr
e size were recorded at every observation. RESULTS Among the 71 subjec
ts, 7 showed positive TSAb in early pregnancy without any thyroid dysf
unction; all 7 developed thyroid dysfunction in the post-partum period
. Five of them (70% of TSAb-positive subjects) developed Graves' disea
se, two showing persistence and three transiently. None of 64 TSAb-neg
ative subjects developed Graves' thyrotoxicosis, though 44 developed v
arious types of thyroid dysfunction as a result of postpartum autoimmu
ne thyroiditis. CONCLUSION The individuals at high risk of post-partum
onset of Graves' thyrotoxicosis can be found early in their pregnancy
by the detection of TSAb. Overall occurrence of post-partum Graves' d
isease in the general population is estimated above 0.54%, that is, on
e in 200 post-partum women may develop Graves' thyrotoxicosis, althoug
h thyrotoxicosis may be transient in half of the patients.