大幅体重减轻对测量和估算肾功能的影响。
Effect of large weight reductions on measured and estimated kidney function.
作者信息
von Scholten Bernt Johan, Persson Frederik, Svane Maria S, Hansen Tine W, Madsbad Sten, Rossing Peter
机构信息
Steno Diabetes Center Copenhagen, Niels Steensens Vej 1, 2820, Gentofte, Denmark.
Hvidovre University Hospital, Hvidovre, Denmark.
出版信息
BMC Nephrol. 2017 Feb 6;18(1):52. doi: 10.1186/s12882-017-0474-0.
BACKGROUND
When patients experience large weight loss, muscle mass may be affected followed by changes in plasma creatinine (pCr). The MDRD and CKD-EPI equations for estimated GFR (eGFR) include pCr. We hypothesised that a large weight loss reduces muscle mass and pCr causing increase in eGFR (creatinine-based equations), whereas measured GFR (mGFR) and cystatin C-based eGFR would be unaffected if adjusted for body surface area.
METHODS
Prospective, intervention study including 19 patients. All attended a baseline visit before gastric bypass surgery followed by a visit six months post-surgery. mGFR was assessed during four hours plasma Cr-EDTA clearance. GFR was estimated by four equations (MDRD, CKD-EPI-pCr, CKD-EPI-cysC and CKD-EPI-pCr-cysC). DXA-scans were performed at baseline and six months post-surgery to measure changes in lean limb mass, as a surrogate for muscle mass.
RESULTS
Patients were (mean ± SD) 40.0 ± 9.3 years, 14 (74%) were female and 5 (26%) had type 2 diabetes, baseline weight was 128 ± 19 kg, body mass index 41 ± 6 kg/m2 and absolute mGFR 122 ± 24 ml/min. Six months post-surgery weight loss was 27 (95% CI: 23; 30) kg, mGFR decreased by 9 (-17; -2) from 122 ± 24 to 113 ± 21 ml/min (p = 0.024), but corrected for current body surface area (BSA) mGFR was unchanged by 2 (-5; 9) ml/min/1.73 m (p = 0.52). CKD-EPI-pCr increased by 12 (6; 17) and MDRD by 13 (8; 18) (p < 0.001 for both), while CKD-EPI-cysC was unchanged by 2 (-8; 4) ml/min/1.73 m (p = 0.51). Lean limb mass was reduced by 3.5 (-4.4;-2.6; p < 0.001) kg and change in lean limb mass correlated with change in plasma creatinine (R = 0.28, p = 0.032).
CONCLUSIONS
Major weight reductions are associated with a reduction in absolute mGFR, which may reflect resolution of glomerular hyperfiltration, while mGFR adjusted for body surface area was unchanged. Estimates of GFR based on creatinine overestimate renal function likely due to changes in muscle mass, whereas cystatin C based estimates are unaffected.
TRIAL REGISTRATION
ClinicalTrials.gov, NCT02138565 . Date of registration: March 24, 2014.
背景
当患者体重大幅减轻时，肌肉量可能会受到影响，随后血浆肌酐（pCr）会发生变化。估算肾小球滤过率（eGFR）的MDRD和CKD-EPI公式中包含pCr。我们假设，体重大幅减轻会降低肌肉量和pCr，从而导致eGFR（基于肌酐的公式）升高，而如果根据体表面积进行调整，实测肾小球滤过率（mGFR）和基于胱抑素C的eGFR将不受影响。
方法
前瞻性干预研究，纳入19例患者。所有患者在胃旁路手术前进行了基线访视，术后6个月进行了随访。通过4小时血浆Cr-EDTA清除率评估mGFR。通过四个公式（MDRD、CKD-EPI-pCr、CKD-EPI-cysC和CKD-EPI-pCr-cysC）估算GFR。在基线和术后6个月进行双能X线吸收法扫描，以测量瘦肢体质量的变化，作为肌肉量的替代指标。
结果
患者的年龄（均值±标准差）为40.0±9.3岁，14例（74%）为女性，5例（26%）患有2型糖尿病，基线体重为128±19 kg，体重指数为41±6 kg/m²，绝对mGFR为122±24 ml/min。术后6个月体重减轻了27（95%置信区间：23；30）kg，mGFR从122±24降至113±21 ml/min，下降了9（-17；-2）ml/min（p = 0.024），但根据当前体表面积（BSA）校正后，mGFR未发生变化，为2（-5；9）ml/min/1.73 m²（p = 0.52）。CKD-EPI-pCr升高了12（6；17）ml/min/1.73 m²，MDRD升高了13（8；18）ml/min/1.73 m²（两者p均<0.001），而CKD-EPI-cysC未发生变化，为2（-8；4）ml/min/1.73 m²（p = 0.51）。瘦肢体质量减少了3.5（-4.4；-2.6）kg，瘦肢体质量的变化与血浆肌酐的变化相关（R = 0.28，p = 0.032）。
结论
体重大幅减轻与绝对mGFR降低有关，这可能反映了肾小球高滤过的缓解，而根据体表面积调整后的mGFR未发生变化。基于肌酐的GFR估算可能因肌肉量的变化而高估肾功能，而基于胱抑素C的估算则不受影响。
试验注册
ClinicalTrials.gov，NCT02138565。注册日期：2014年3月24日。
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