Elevated fasting and postprandial C-terminal telopeptide after Roux-en-Y gastric bypass

Area of Science:

• Endocrinology
• Bariatric Surgery
• Bone Metabolism

Background:

• Roux-en-Y gastric bypass (RYGB) alters bile acid profiles, impacting bone resorption.
• Despite RYGB's benefits, long-term bone loss risk is a concern.
• Bile acids are implicated in postprandial suppression of bone resorption markers.

Purpose of the Study:

• To investigate the relationship between RYGB, bile acids, and bone resorption markers.
• To assess changes in parathyroid hormone and C-terminal telopeptide (CTX) post-RYGB.
• To evaluate the long-term skeletal implications of RYGB.

Main Methods:

• Studied 36 obese individuals before and 15 months after RYGB.
• Collected blood samples pre- and post-mixed meal (120 min).
• Analyzed total bile acids, parathyroid hormone, and CTX.

Main Results:

• RYGB led to a significant increase in peak postprandial total bile acids (4.9-fold).
• Parathyroid hormone levels remained unchanged post-surgery.
• Fasting and postprandial CTX levels increased significantly post-RYGB.

Conclusions:

• Post-RYGB, elevated bile acids and CTX exceed reference ranges, even with vitamin D supplementation.
• Increased bile acids do not counteract the bone resorptive signal in the gut-bone axis.
• Serial CTX measurements may predict skeletal pathology in RYGB patients.