Low estriol levels in the maternal marker screen as a predictor of X-linked adrenal hypoplasia congenita: Case report

INTRODUCTION: X-linked adrenal hypoplasia congenita (AHC) is a rare cause of adrenocortical insufficiency. Early postnatal diagnosis may prevent severe hypoglycemia, Addisonian crises and death. Low maternal estriol (E3) levels in the second trimester of pregnancy could indicate the possibility that the fetus suffers from a disorder that causes adrenal insufficiency. Suspicion is based on the fact that E3 originates from dehydroepiandrosterone (DHEA) synthesized in the fetal adrenals. In case of adrenal insufficiency, the impaired production of fetal DHEA leads to a subsequent reduction of E3 concentrations in maternal serum. There are only a few reports of AHC suspected prenatally due to low maternal E3 levels. CASE OUTLINE: We describe two brothers with adrenal insufficiency due to AHC. The older brother was admitted to the hospital at the age of 33 days due to failure to thrive, vomiting, and dehydration. Genetic analysis revealed a hemizygous mutation in DAX-1 gene, thus confirming the diagnosis of ACH. The same mutation was detected in his mother. In the second pregnancy, E3 concentrations were determined from maternal serum. Estriol levels during the second trimester were extremely low suggesting the diagnosis of AHC. The diagnosis was confirmed during the neonatal period by genetic testing, and replacement therapy was started at the age of 10 days. This boy never experienced an adverse episode such as hypoglycemia or adrenal crises. CONCLUSION: Since determination of E3 is a simple, sensitive, noninvasive and cheap method, its use as an obligatory prenatal screening test should be accepted as a standard practice in Serbia.