ENDOCRINOLOGY AND RESPIRATORY DISTRESS SYNDROME (RDS)

Three thousand newborn babies die each year of respiratory distress syndrome (RDS). In addition, about 30,000 babies in the United States have RDS each year.

Also called hyaline membrane disease, RDS is a lung disorder, found mainly in newborn babies who are born prematurely. The disease causes difficulty in breathing because the lungs are immature and lack enough surfactant, a detergent-like substance that keeps the lungs' air spaces open. RDS leads to the gradual collapse of the lungs, which results in harm to other organs. The babies who recover are also at greater risk of other problems such as heart failure, kidney failure, intestinal disease, bleeding into the brain, chronic lung disease, cerebral palsy, and, later in life, learning disorders.

RDS is expensive, with the special medical care alone costing this nation more than $100 million each year. Prevention or improved treatment would not only save this expense, but would also reduce the suffering of the baby and family, and improve the quality of life for these babies.

Nearly all babies born before 32 weeks of pregnancy will have RDS, and about 25 percent of these very premature babies will die of RDS and associated problems.

The usual treatment is to give the baby oxygen and assisted breathing with a mechanical respirator. Recently, treatment has included giving babies replacement surfactant.

Endocrine research has contributed to both preventing and treating RDS more effectively.

Animal studies have shown that hormone treatment can accelerate lung development before birth and improve the lungs' functioning after birth. These studies have led to a safe and effective new treatment for women who are about to give birth prematurely. These women now receive betamethasone, a synthetic adrenal hormone, which cuts the RDS rate in half and prevents other health problems as well. This treatment also increases the effectiveness of the artificial surfactant that is given to newborns with RDS.

Because some treated babies still develop RDS, further research is needed to clarify how hormones regulate lung development and to discover other methods of preventing or treating RDS. Recent basic and clinical studies suggest that babies treated with the combination of two hormones given to the mother – adrenal and thyroid hormones – have less RDS and less long-term lung disease than those with mothers receiving only one hormone.

Further studies have discovered that other types of hormones can also stimulate lung development, suggesting that more advances in treatment may be forthcoming. Continued basic and clinical endocrine research is needed to determine the safety and effectiveness of current treatments and to develop new and more effective approaches.

Basic studies on how hormones affect lung development led directly to clinical studies on how to prevent RDS. Similarly, current basic endocrine research on hormone effects has led to the recent clinical trials of combined hormonal therapy.