Preeclampsia is Strongly Associated with Maternal Hypothyroidism

Overt hypothyroidism in pregnancy may be associated with a preeclampsia-like syndrome that carries a high risk of adverse obstetric outcomes. Hypothyroidism can lead to vascular smooth muscle contraction in systemic and renal vessels, which may lead to increased peripheral vascular resistance, diastolic hypertension, and decreased tissue perfusion. We assessed the frequency of detection of undiagnosed hypothyroidism in the presence of preeclampsia. From a cohort of, 105 preeclamptic inpatients evaluated between January 2003 and June 2006, 50 underwent screening for thyroid disease and constituted the study population. A diagnosis of hypothyroidism was made on the basis of thyroid stimulatig hormone >2 μUI/ml (normal values for adult: 0,27-4,2 μUI/ml) and free T4 < 9 ñg/ml (normal value: 9.3-17.3 ñg/ml) Clinical characteristics and obstetric outcomes were evaluated according to diagnosis of hypothyroidism. A p-value <0. 05 was considered statistically significant. 28/50 pts (56%) had hypothyroidism. Hypothyroid and euthyroid patients did not differ in clinical characteristics: age (33±5 vs 33±3), rate of nulliparity (75% vs 95% P=0,054), BMI (25±4 vs 25±3), severity of preeclampsia (severe preeclampsia or HELLP) (21% vs 40% P=0,14), and obstetric outcomes: gestational age at delivery (32.9±3.7 vs 32.9±4.1 weeks), birth weight (1615±816 vs 1490±748 grams P=0,58), cord pH (7.27±0.08 vs 7.32±0.07), rates of abruption (3,5% vs 4,5%) and 5-minute Apgar scores <7 (3,5% vs 4,5%). 56% of screened preeclamptic patients had hypothyroidism. This finding suggests that thyroid function should be assessed in the presence of preeclampsia.