Copper and Zinc Serum Levels after Derivative Bariatric Surgery: Differences Between Roux-en-Y Gastric Bypass and Biliopancreatic Diversion

There are limited data on the prevalence of copper and zinc deficiency in the long term after bariatric surgery.

We analysed copper and zinc serum levels in a cohort of 141 patients, 52 who underwent Roux-en-Y gastric bypass (RYGB) and 89 biliopancreatic diversion (BPD), with a follow-up of 5 years.

Mean copper level was significantly lower in the BPD group (P < 0.0001 vs. RYGB). Forty-five (50.6%) BPD patients had, at least once, a low copper level, and half of them, 27 (30.3%) patients, had repeatedly low levels. In this group, serum copper level correlated positively with total leukocyte and granulocyte count (r = 0.14, P = 0.002, and r = 0.17, P < 0.001, respectively). However, no patient had clinical evidence of haematological or neurological disorders. Only two RYGB patients (3.8%) had copper deficiency. Mean zinc level was also significantly lower in the BPD group (P < 0.0001). All but one BPD patient had hypozincaemia at least once, and the percentage of patients with hypozincaemia ranged from 44.9% to 74.2%. In RYGB patients, zinc deficiency peaked at 48 and 60 months (15.4% and 21.2%, respectively). The zinc level was determined by the alimentary limb length in this group, but the common channel length had no influence on copper and zinc levels in the BPD group.

Hypocupremia, and especially hypozincaemia, are frequent findings in BPD patients, but rarely found in patients who underwent RYGB, particularly short RYGB. Our data also suggest that a long-standing and severe hypocupremia is required to develop neurological and haematological disorders after bariatric surgery.