Gestational Hypothyroidism Higher Than Estimated

But less than a quarter of pregnant women undergo screening for gestational hypothyroidism

TUESDAY, Jan. 10 (HealthDay News) -- Nearly one in six pregnant women who are tested suffer from gestational hypothyroidism, but less than a quarter of pregnant women undergo screening, according to a study published online Dec. 14 in the Journal of Clinical Endocrinology & Metabolism.

Amy J. Blatt, Ph.D., of Quest Diagnostics in West Norriton, Pa., and colleagues analyzed records from a national sample of 502,036 pregnant women (aged 18 to 40 years) who underwent gestational hypothyroidism testing from June 2005 through May 2008. Using assay-specific, trimester-specific, reference intervals, the rates and prevalence of hypothyroidism during pregnancy and postpartum was assessed, based on thyroid stimulating hormone (TSH) levels.

The researchers found that 23 percent of the pregnant women were tested for subclinical or overt gestational hypothyroidism. Positive results were seen for 15.5 percent of those tested. Twenty-four percent of women with TSH within range, and 33 percent with elevated TSH, were also tested for gestational hypothyroxinemia, with positive results seen in 0.2 and 2.4 percent of those tested, respectively. Thyroperoxidase antibody testing was performed in 0.3 percent of women with TSH within range, and 0.66 percent of women with elevated TSH, with 15 and 65 percent testing positive, respectively. Of the hypothyroid women, only 20.7 percent received thyroid screening within six months postpartum, 11.5 percent of whom were diagnosed with postpartum hypothyroidism.

"Gestational hypothyroidism is more common than generally acknowledged. Testing is not common and test selection is variable. There is a low rate of postpartum follow-up," the authors write.

The authors are employees of Quest Diagnostics.

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