Malabsorptive gastric bypass in patients with super obesity: A comparative study of roux limb length

Although Roux-en-Y Gastric Bypass (RYGB) remains the most effective treatment for obesity and type 2 diabetes (T2D), many patients fail to achieve remission, or relapse. Increasing intestinal limb lengths of RYGB may improve outcomes, but the mechanistic basis for this remains unclear. We hypothesize biliopancreatic (BP) limb length modulates the antidiabetic effect of RYGB. Rats underwent RYGB with a 20-cm (RYGB-20cm) or 40-cm (RYGB-40cm) BP limb and were compared with control animals. After 2 and 4 wk, portal and systemic blood was sampled during intestinal glucose infusion. Portosystemic gradient was used to calculate intestinal glucose utilization (Gutil), absorption (Gabsorp), and hormone secretion. Intestinal morphology and gene expression were assessed. At 2 wk, Gabsorp progressively decreased with increasing BP limb length; this pattern persisted at 4 wk. Gutil increased ≈70% in both RYGB-20cm and -40cm groups at 2 wk. At 4 wk, Gutil progressively increased with limb length. Furthermore, Roux limb weight, and expression of hexokinase and preproglucagon, exhibited a similar progressive increase. At 4 wk, glucagon-like peptide-1 and -2 levels were higher after RYGB-40cm, with associated increased secretion. We conclude that BP limb length modulates multiple antidiabetic mechanisms, analogous to the dose-response relationship of a drug. Early postoperatively, a longer BP limb reduces Gabsorp. Later, Gutil, Roux limb hypertrophy, hormone secretion, and hormone levels are increased with longer BP limb. Sustained high incretin levels may prevent weight regain and T2D relapse. These data provide the basis for customizing BP limb length according to patient characteristics and desired metabolic effect. NEW & NOTEWORTHY Biliopancreatic limb length in gastric bypass modulates multiple antidiabetic mechanisms, analogous to the dose-response relationship of a drug. With a longer biliopancreatic limb, Roux limb hypertrophy, increased glucose utilization, reduced glucose absorption, and sustained high incretin levels may prevent weight regain and diabetes relapse.

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Hyperparathyroidism and Vitamin D Deficiency after Laparoscopic Gastric Bypass

The American Surgeon ◽

10.1177/000313480807400603 ◽

2008 ◽

Vol 74 (6) ◽

pp. 469-475 ◽

Cited By ~ 11

Author(s):

Ronald H. Clements ◽

Kishore Yellumahanthi ◽

Mary Wesley ◽

Naveen Ballem ◽

Kirby I. Bland

Keyword(s):

Body Mass Index ◽

Vitamin D ◽

Gastric Bypass ◽

Racial Differences ◽

Body Mass ◽

Laparoscopic Gastric Bypass ◽

Serum Vitamin ◽

Inverse Correlation ◽

Limb Length ◽

Roux Limb

Hyperparathyroidism (HPT) can occur after gastric bypass because of the alteration in vitamin D and calcium absorption. Adequate serum vitamin D concentrations have not been clearly defined in this patient population. Vitamin D (Vit D) and parathyroid hormone (PTH) were assessed 1 year after laparoscopic gastric bypass (LGB). The prevalence of HPT and Vit D deficiency were determined and their association was evaluated using Fisher's exact test. Ninety-three patients (aged 44 ± 1.1 years, 49.6 ± 0.67 kg/m2 body mass index, 79.6% female, 69.6% white) were evaluated. The prevalence of Vit D deficiency (less than 20 ng/mL) and HPT (greater than 65 pg/mL) was 23.6 per cent (n = 22) and 25.7 per cent (n = 28), respectively. Among patients with HPT, only eight of 28 (28.6%) had Vit D deficiency, and of those with Vit D deficiency, only eight of 22 (36.4%) had HPT. There was a weak inverse correlation (r = –0.37) between PTH and Vit D. Blacks are at higher risk for Vit D deficiency. There was no significant association between Vit D deficiency and HPT, Vit D deficiency and Roux limb length, or HPT and Roux limb length. After LGB, Vit D deficiency and hyperparathyroidism occur commonly. Body mass index and Roux limb length are not associated with these two conditions, but racial differences do exist. There is a weak inverse correlation between Vit D and PTH. Further research is needed to elucidate the causes, treatments, and significance of HPT after LGB.

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