Department of Nephrology, Tawam Hospital, Al Ain, United Arab Emirates.
Int Urol Nephrol. 2013 Feb;45(1):157-62. doi: 10.1007/s11255-012-0131-2. Epub 2012 Mar 3.
Glomerular hyperfiltration commonly associated with obesity is expected to improve postbariatric surgery. However, formula-based glomerular filtration rate (GFR) estimation in these patients is limited by body size confounders necessitating use of modified equations, the reliability of which remains uncertain.
In this study, various GFR-estimating formulae were compared in morbidly obese patients at baseline and postbariatric surgery. Through a retrospective chart review, we identified 220 patients who had undergone this procedure, with over 6-month follow-up, during which major weight reduction was achieved.
A significant decrease in BP and glomerular hyperfiltration was observed, though there was large variability in GFR estimation using the different formulae. Gross over and underestimation was observed which improved with correction for body size confounders especially lean body weight (LBW). Postoperatively, significant attenuation in estimated GFR was demonstrated when LBW or body surface area-adjusted versions were used. In a subgroup of patients with chronic kidney disease, a significant improvement in GFR was seen postoperatively with the LBW-modified formula but there were again inconsistencies when using other equations.
Though clinicians must be critical in the application of GFR estimates to patient care, LBW adjustment appears to be the most practical solution to its estimation in the obese patients. This is particularly true for patients with normal renal function but appears to be also applicable to those with compromised kidney function. Future studies are needed to compare these equations with a gold standard GFR measure as well as to explore whether the renal benefits from bariatric surgery are sustained or seen in more advanced CKD stages.
与肥胖相关的肾小球高滤过通常会在减重手术后得到改善。然而，由于肥胖患者的身体大小存在混杂因素，基于公式的肾小球滤过率（GFR）估计方法受到限制，需要使用改良方程，但其可靠性仍不确定。
本研究比较了肥胖患者基线和减重手术后不同 GFR 估计公式的差异。通过回顾性病历分析，我们确定了 220 名接受过该手术的患者，随访时间超过 6 个月，在此期间患者实现了体重的显著减轻。
我们观察到血压和肾小球高滤过显著下降，但不同公式的 GFR 估计值存在较大差异。使用身体大小的混杂因素（尤其是瘦体重）进行校正后，可以明显减少总体高估和低估的情况。术后，当使用瘦体重或体表面积校正版本的公式时，估计的 GFR 显著降低。在慢性肾脏病患者亚组中，使用瘦体重改良公式后 GFR 显著改善，但使用其他方程时仍存在不一致性。
尽管临床医生在将 GFR 估计值应用于患者护理时必须谨慎，但对于肥胖患者 GFR 的估计，瘦体重校正似乎是最实用的解决方案。对于肾功能正常的患者尤其如此，但似乎也适用于肾功能受损的患者。未来需要进行研究，比较这些方程与 GFR 的金标准测量方法，并探讨减重手术对肾脏的益处是否持续存在，或者是否在更晚期的 CKD 阶段显现。
