Gref Margareta, Karp Kjell
Department of Clinical Physiology, Institution of Surgical and Perioperative Sciences, Umeå University, Umeå, Sweden.
Nephrol Dial Transplant. 2007 Nov;22(11):3166-73. doi: 10.1093/ndt/gfm411. Epub 2007 Aug 3.
Glomerular filtration rate is a key parameter in kidney disease. The Radionuclides in Nephrourology Committee has recommended a single-sample method with 99mTc-DTPA based on the mean sojourn time. This study was done to develop the method for use with iohexol making the method more available.
The single-sample formula was derived for group I (n = 48, Cl = 8-188 ml/min) and applied on group II (n = 47) and on group III (n = 123). In groups I and II, reference clearance was determined according to Sapirstein and in group III according to Brøchner-Mortensen.
The formula Cls= (-b+sqrt b2-4ac)/(2a) (a = (-6.49 x 10(-6) x t + 8.85 x 10(-4)) x t, b = 1.143 x t and c = ln(C(t))x(ECV/Q0) was derived for patients with estimated Cl > 30 ml/min with the best result if the single sample was obtained between 4 and 5 h. Extracellular volume was estimated as ECV =9985 x BSA - 3431. The formula ClS(24 h) = -ln(C(t)) x (ECV/Q0)/(t) was developed for patients with estimated Cl <30 ml/min with a single sample at 24 h. With this combined approach SDdiff was 2.7 ml/min in group II and 3.1 ml/min in group III.
An accurate determination of iohexol clearance can be obtained from a single plasma sample applying the mean sojourn time approach. A separate formula must be used for patients with low clearance values. Body surface area (BSA), injected amount of iohexol (Q0), time when the single sample is drawn (t) and the concentration of iohexol [C(t)] in the sample are needed for the calculations.
肾小球滤过率是肾脏疾病的关键参数。核医学肾脏病委员会推荐了一种基于平均滞留时间的99mTc - DTPA单样本方法。本研究旨在开发一种使用碘海醇的方法，使该方法更易于应用。
为第一组（n = 48，Cl = 8 - 188 ml/min）推导单样本公式，并应用于第二组（n = 47）和第三组（n = 123）。在第一组和第二组中，根据萨皮尔斯坦法测定参考清除率，在第三组中根据布罗克纳 - 莫滕森法测定。
对于估计Cl>30 ml/min的患者，推导了公式Cls = (-b + √b² - 4ac)/(2a)（a = (-6.49×10⁻⁶×t + 8.85×10⁻⁴)×t，b = 1.143×t，c = ln(C(t))×(ECV/Q0)），如果在4至5小时之间采集单样本，结果最佳。细胞外液量估计为ECV = 9985×BSA - 3431。对于估计Cl<30 ml/min的患者，在24小时采集单样本，开发了公式ClS(24 h) = -ln(C(t))×(ECV/Q0)/(t)。采用这种联合方法，第二组的SDdiff为2.7 ml/min，第三组为3.1 ml/min。
应用平均滞留时间方法，从单个血浆样本中可准确测定碘海醇清除率。对于清除率值较低的患者，必须使用单独的公式。计算需要体表面积（BSA）、碘海醇注射量（Q0）、采集单样本的时间（t）以及样本中碘海醇的浓度[C(t)]。
