Serotonin Levels After Sleeve Gastrectomy
Sleeve gastrectomy does not cause you to "lose" serotonin in a clinically meaningful way, but serotonin levels do change after surgery and may be associated with weight regain patterns. 1, 2
What Happens to Serotonin After Sleeve Gastrectomy
Serotonin Changes Are Variable and Patient-Specific
Serotonin levels show a positive correlation with BMI in patients who regain weight after sleeve gastrectomy, suggesting that serotonin plays a role in energy homeostasis regulation rather than being simply "lost." 2
In a prospective study of 92 sleeve gastrectomy patients followed for two years, 16% regained weight and showed positive correlations between serotonin levels and BMI, while 84% who maintained weight loss had different serotonin patterns. 2
Baseline serotonin levels and the serotonin/5-hydroxytryptophan ratio predict slow weight loss in the early postoperative period, with an area under the curve of 0.79-0.80 for predicting poor weight loss outcomes at six months. 1
The Mechanism Is Neurohormonal, Not Simple Depletion
Sleeve gastrectomy removes two-thirds to three-fourths of the stomach, including the fundus, which exerts hormonal influences primarily through ghrelin reduction, not serotonin depletion. 3
Weight loss mechanisms after sleeve gastrectomy are attributable to both gastric restriction and neurohormonal changes, with serotonin contributing to the interplay of regulatory systems rather than being depleted. 2
Clinical Implications for Serotonin-Related Medications
Antidepressant Management After Sleeve Gastrectomy
Sertraline absorption may be enhanced by opening capsules rather than swallowing whole, as gastric volume is reduced but the small intestine remains intact. 4
SSRIs including sertraline are weight-neutral or associated with modest weight loss and should not negatively affect excess weight loss results after sleeve gastrectomy. 4
If sertraline is ineffective or poorly tolerated, bupropion is an alternative antidepressant associated with weight loss rather than weight gain. 4
Important Medication Interactions
Opioids with serotonin reuptake inhibitory activity (levorphanol, meperidine, fentanyl, methadone, tapentadol, tramadol) increase the risk of serotonin syndrome when combined with SSRIs or other serotonergic agents. 3
Concomitant use of butorphanol or nalbuphine with serotonergic agents may result in increased risk of serotonin syndrome. 3
What You Actually Need to Monitor
Nutritional Deficiencies Are the Real Concern
Daily supplementation with 1-2 adult dose multivitamins is recommended after sleeve gastrectomy to prevent nutritional deficiencies. 3
Thiamine, folate, and magnesium deficiencies have been reported in 0-29%, 0-24%, and rare cases respectively after restrictive bariatric procedures. 3
Vitamin B12 deficiency occurs in approximately 62% of patients and requires annual monitoring, as it can lead to irreversible neurological damage if untreated. 5
Long-Term Monitoring Schedule
Year 1 post-surgery: vitamin and mineral panels every 3 months. 5
Year 2 post-surgery: testing every 6 months. 5
Beyond Year 2: lifelong annual laboratory monitoring including CBC, ferritin, B12, folate, vitamin D, calcium, PTH, comprehensive metabolic panel, HbA1c, and lipid profile. 5
Critical Pitfalls to Avoid
Never assume serotonin "depletion" is causing symptoms—the relationship between serotonin and weight outcomes is complex and bidirectional, not a simple deficiency state. 1, 2
Do not stop SSRIs out of concern for serotonin levels—these medications are safe and weight-neutral after sleeve gastrectomy. 4
Be vigilant for serotonin syndrome when combining serotonergic medications, particularly in the perioperative period when multiple agents may be used. 3
Focus monitoring efforts on proven nutritional deficiencies (B12, iron, thiamine, folate, vitamin D) rather than serotonin levels, which are not routinely measured or clinically actionable. 3, 5, 6