Pre-flight body weight effects on urinary calcium excretion in space

Area of Science:

• Space medicine
• Human physiology
• Bone metabolism

Background:

• Microgravity causes bone loss and increases urinary calcium, elevating kidney stone risk.
• Individual responses to microgravity vary, necessitating identification of predictive factors.

Purpose of the Study:

• To investigate the association between pre-flight body weight and in-flight urinary calcium excretion.
• To identify pre-flight characteristics for astronaut risk assessment.

Main Methods:

• Analysis of urinary calcium excretion data from Skylab and International Space Station (ISS) missions.
• Inclusion of 45 astronauts (9 Skylab, 36 ISS) from the Longitudinal Study of Astronaut Health (LSAH) database.

Main Results:

• Both astronaut body weight and duration of spaceflight positively correlated with urinary calcium excretion.
• An interaction effect showed higher pre-flight weight was linked to earlier and greater calcium excretion during the mission.

Conclusions:

• Pre-flight body weight is a significant predictor of increased urinary calcium excretion in microgravity.
• Incorporating pre-flight weight into risk assessments can help manage bone loss and kidney stone formation in astronauts.