Milo Gai, Feige Gross Nevo Revital, Pazgal Idit, Gafter-Gvili Anat, Shpilberg Ofer, Gafter Uzi, Erman Arie, Stark Pinhas
Department of Nephrology and Hypertension, Rabin Medical Center, Petah-Tikva, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and.
Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and Institute of Hematology, Rabin Medical Center, Petah-Tikva, Israel.
Clin J Am Soc Nephrol. 2015 Aug 7;10(8):1350-6. doi: 10.2215/CJN.12181214. Epub 2015 May 11.
Patients with β-thalassemia major (TM) may have tubular dysfunction and glomerular dysfunction, primarily hyperfiltration, based on eGFR. Assessment of GFR based on serum creatinine concentration may overestimate GFR in these patients. This study sought to determine GFR by using inulin clearance and compare it with measured creatinine clearance (Ccr) and eGFR.
DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS: Patients followed up in an Israeli thalassemia clinic who had been regularly transfused for years and treated with deferasirox were included in the study. They were studied by inulin clearance, Ccr, the CKD Epidemiology Collaboration and the Modification of Diet in Renal Disease equations for eGFR, and the Cockcroft-Gault estimation for Ccr. Expected creatinine excretion rate and tubular creatinine secretion rate were calculated.
Nine white patients were studied. Results, given as medians, were as follows: serum creatinine was 0.59 mg/dl (below normal limits); GFR was low (76.6 ml/min per 1.73 m(2)) and reached the level of CKD; Ccr was 134.9 ml/min per 1.73 m(2), higher than the GFR because of a tubular creatinine secretion rate of 30.3 ml/min per 1.73 m(2) (this accounted for 40% of the Ccr); and eGFR calculated by the CKD Epidemiology Collaboration and Modification of Diet in Renal Disease equations and Cockcroft-Gault-estimated Ccr were 133, 141, and 168 ml/min per 1.73 m(2), respectively. These latter values were significantly higher than the GFR, reaching the hyperfiltration range, and indicated that the estimation techniques were clinically unacceptable as a method for measuring kidney function compared with the GFR according to Bland and Altman analyses.
Contrary to previous reports, patients in this study with TM had normal or reduced GFR. The estimating methods showed erroneous overestimation of GFR and were clinically unacceptable for GFR measurements in patients with TM by Bland and Altman analysis. Therefore, more accurate methods should be used for early detection of reduced GFR and prevention of its further decline toward CKD in these patients.
重型β地中海贫血（TM）患者可能存在肾小管功能障碍和肾小球功能障碍，主要表现为基于估算肾小球滤过率（eGFR）的超滤过。在这些患者中，基于血清肌酐浓度评估肾小球滤过率（GFR）可能会高估GFR。本研究旨在通过菊粉清除率测定GFR，并将其与实测肌酐清除率（Ccr）和eGFR进行比较。
设计、地点、参与者及测量方法：纳入在以色列地中海贫血诊所随访多年、定期输血并接受地拉罗司治疗的患者。通过菊粉清除率、Ccr、慢性肾脏病流行病学协作组公式和肾脏病饮食改良公式计算eGFR，以及Cockcroft-Gault公式估算Ccr对患者进行研究。计算预期肌酐排泄率和肾小管肌酐分泌率。
研究了9例白人患者。结果（以中位数表示）如下：血清肌酐为0.59mg/dl（低于正常范围）；GFR较低（76.6ml/min/1.73m²），已达到慢性肾脏病水平；Ccr为134.9ml/min/1.73m²，高于GFR，因为肾小管肌酐分泌率为30.3ml/min/1.73m²（占Ccr的40%）；慢性肾脏病流行病学协作组公式、肾脏病饮食改良公式计算的eGFR以及Cockcroft-Gault公式估算的Ccr分别为133、141和168ml/min/1.73m²。后几个值显著高于GFR，达到超滤过范围，根据Bland和Altman分析，表明与基于GFR测量肾功能的方法相比，这些估算技术在临床上不可接受。
与既往报道相反，本研究中的TM患者GFR正常或降低。估算方法显示对GFR存在错误高估，根据Bland和Altman分析，在TM患者中用于GFR测量在临床上不可接受。因此，应使用更准确的方法来早期检测这些患者GFR降低，并预防其进一步向慢性肾脏病发展。
