Johnson Jason M, Maher James W, DeMaria Eric J, Downs Robert W, Wolfe Luke G, Kellum John M
Department of Surgery, Virginia Commonwealth University School of Medicine, Richmond, 23298, USA.
Ann Surg. 2006 May;243(5):701-4; discussion 704-5. doi: 10.1097/01.sla.0000216773.47825.c1.
Alterations of the endocrine system in patients following Roux-en-Y gastric bypass (GBP) are poorly described and have prompted us to perform a longitudinal study of the effects of GBP on serum calcium, 25-hydroxy-vitamin-D (vitamin D), and parathyroid hormone (PTH).
Prospectively collected data were compiled to determine how GBP affects serum calcium, vitamin D, and PTH. Student t test, Fisher exact test, or linear regression was used to determine significance.
Calcium, vitamin D, and PTH levels were drawn on 243 patients following GBP. Forty-one patients had long-limb bypass (LL-GBP), Roux >100 cm, and 202 had short-limb bypass (SL-GBP), Roux < or =100 cm. The mean (+/-SD) postoperative follow-up time was significantly longer in the LL-GBP group (5.7 +/- 2.5 years) than the SL-GBP group (3.1 +/- 3.6 years, P < 0.0001). When corrected for albumin levels, mean calcium was 9.3 mg/dL (range, 8.5-10.8 mg/dL), and no difference existed between LL-GBP and SL-GBP patients. For patients with low vitamin D levels (<8.9 ng/mL), 88.9% had elevated PTH (>65 pg/mL) and 58.0% of patients with normal vitamin D levels (> or =8.9 ng/mL) had elevated PTH (P < 0.0001). In individuals with vitamin D levels <30 ng/mL, 55.1% (n = 103) had elevated PTH, and of those with vitamin D levels > or =30 ng/mL 28.5% (n = 16) had elevated PTH (P = 0.0007). Mean vitamin D levels were lower in patients who had undergone LL-GBP as opposed to those with SL-GBP, 16.8 +/- 10.8 ng/mL versus 22.7 +/- 11.1 ng/mL (P = 0.0022), and PTH was significantly higher in patients who had a LL-GBP (113.5 +/- 88.0 pg/mL versus 74.5 +/- 52.7 pg/mL, P = 0.0002). There was a linear decrease in vitamin D (P = 0.005) coupled with a linear increase in PTH (P < 0.0001) the longer patients were followed after GBP. Alkaline phosphatase levels were elevated in 40.3% of patients and correlated with PTH levels.
Vitamin D deficiency and elevated PTH are common following GBP and progress over time. There is a significant incidence of secondary hyperparathyroidism in short-limb GBP patients, even those with vitamin D levels > or =30 ng/mL, suggesting selective Ca malabsorption. Thus, calcium malabsorption is inherent to gastric bypass. Careful calcium and vitamin D supplementation and long-term screening are necessary to prevent deficiencies and the sequelae of secondary hyperparathyroidism.
Roux-en-Y胃旁路术（GBP）患者内分泌系统的改变描述较少，这促使我们对GBP对血清钙、25-羟基维生素D（维生素D）和甲状旁腺激素（PTH）的影响进行纵向研究。
汇总前瞻性收集的数据，以确定GBP如何影响血清钙、维生素D和PTH。采用学生t检验、Fisher精确检验或线性回归来确定显著性。
对243例行GBP手术的患者进行了钙、维生素D和PTH水平检测。41例患者行长肢旁路术（LL-GBP），Roux袢>100 cm，202例患者行短肢旁路术（SL-GBP），Roux袢≤100 cm。LL-GBP组术后平均随访时间（5.7±2.5年）显著长于SL-GBP组（3.1±3.6年，P<0.0001）。校正白蛋白水平后，平均血钙为9.3mg/dL（范围8.5-10.8mg/dL），LL-GBP组和SL-GBP组患者之间无差异。维生素D水平低（<8.9ng/mL）的患者中，88.9%的患者PTH升高（>65pg/mL），维生素D水平正常（≥8.9ng/mL）的患者中58.0%的患者PTH升高（P<0.0001）。维生素D水平<30ng/mL的个体中，55.1%（n=103）的患者PTH升高，维生素D水平≥30ng/mL的个体中28.5%（n=16）的患者PTH升高（P=0.0007）。与SL-GBP组患者相比，LL-GBP组患者的平均维生素D水平较低，分别为16.8±10.8ng/mL和22.7±11.1ng/mL（P=0.0022），LL-GBP组患者的PTH显著更高（113.5±88.0pg/mL对74.5±52.7pg/mL，P=0.0002）。GBP术后随访时间越长，维生素D呈线性下降（P=0.005），同时PTH呈线性升高（P<0.0001）。40.3%的患者碱性磷酸酶水平升高，且与PTH水平相关。
GBP术后维生素D缺乏和PTH升高很常见，且随时间推移而进展。短肢GBP患者继发性甲状旁腺功能亢进的发生率很高，即使是维生素D水平≥30ng/mL的患者，提示存在选择性钙吸收不良。因此，钙吸收不良是胃旁路术固有的。需要仔细补充钙和维生素D并进行长期筛查，以预防缺乏症和继发性甲状旁腺功能亢进的后遗症。
