Long-duration space flight and bed rest effects on testosterone and other steroids.

Context: Limited data suggest that testosterone is decreased during space flight, which could contribute to bone and muscle loss.

Objective: The main objective was to assess testosterone and hormone status in long- and short-duration space flight and bed rest environments and to determine relationships with other physiological systems, including bone and muscle.

Design: Blood and urine samples were collected before, during, and after long-duration space flight.

Thyroid status of Space Shuttle crewmembers: effects of iodine removal.

Introduction: Iodine is often used for water purification and has been used throughout the U.S. space program.