Henriksen Ulrik Lütken, Henriksen Jens H, Bendtsen Flemming, Møller Søren
Clinical Physiology and Nuclear Medicine 239, Center of Functional and Diagnostic Imaging and Research, Hvidovre Hospital, University of Copenhagen, Copenhagen, Denmark.
Clin Physiol Funct Imaging. 2013 May;33(3):211-7. doi: 10.1111/cpf.12015. Epub 2012 Dec 26.
Determination of plasma volume (PV) is important in several clinical situations. Thus, patients with liver disease often have augmented PV as part of their sodium-water retention. This study was undertaken to compare PV determination by two indicators: technetium-labelled human serum albumin ((99m) Tc-HSA) and iodine-labelled human serum albumin ((125) I-HSA), as the former may have advantages at repeated measurements and the latter is the classical gold standard.
In 88 patients, (64 with liver disease, mainly cirrhosis, and 24 patients without liver disease), simultaneous measurements of PV were taken with (99m) Tc-HSA and (125) I-HSA after 1 h in the supine position. Blood samples were obtained before and 10 min after quantitative injection of the two indicators. In a subset of patients (n = 32), the measurements were repeated within 1 h.
In all patients, a close correlation was present between PV determined by the two indicators (r = 0·89, P<0·0001). In all, but twelve patients, a higher PV was obtained with (99m) Tc-HSA compared with (125) I-HSA (P<0·0001). PV determined with (99m) Tc-HSA exceeded PV determined with (125) I-HSA by 367 ml (5·2 ml kg(-1) ) in liver patients as compared to 260 ml (3·5 ml kg(-1) ) in patients without liver disease (P<0·05). The precision of repeated PV determination was 1·75% (coefficient of variation) with (99m) Tc-HSA and 1·71% with (125) I-HSA (ns), and similar values were found in patients with and without liver disease.
The study demonstrates that (99m) Tc-HSA has the same precision as that of (125) I-HSA. However, especially in patients with liver disease, (99m) Tc-HSA consistently overestimates the PV, most likely owing to indicator heterogeneity with subsequent fast removal from the circulating medium with a higher volume of distribution as the outcome.
在多种临床情况下，测定血浆容量（PV）都很重要。例如，肝病患者常因钠水潴留而出现血浆容量增加。本研究旨在比较两种指标测定血浆容量的情况：锝标记人血清白蛋白（（99m）Tc - HSA）和碘标记人血清白蛋白（（125）I - HSA），因为前者在重复测量时可能具有优势，而后者是经典的金标准。
88例患者（64例患有肝病，主要为肝硬化，24例无肝病），在仰卧位1小时后，同时用（99m）Tc - HSA和（125）I - HSA测量血浆容量。在定量注射这两种指标之前和之后10分钟采集血样。在一部分患者（n = 32）中，在1小时内重复测量。
在所有患者中，两种指标测定的血浆容量之间存在密切相关性（r = 0·89，P<0·0001）。除12例患者外，与（125）I - HSA相比，（99m）Tc - HSA测得的血浆容量更高（P<0·0001）。肝病患者用（99m）Tc - HSA测定的血浆容量比用（125）I - HSA测定的超出367 ml（5·2 ml·kg⁻¹），无肝病患者超出260 ml（3·5 ml·kg⁻¹）（P<0·05）。用（99m）Tc - HSA重复测定血浆容量的精密度为1·75%（变异系数），用（125）I - HSA为1·71%（无显著差异），有肝病和无肝病患者中均发现类似数值。
该研究表明，（99m）Tc - HSA与（125）I - HSA具有相同的精密度。然而，尤其是在肝病患者中，（99m）Tc - HSA始终高估血浆容量，最可能的原因是示踪剂异质性，随后从循环介质中快速清除，导致分布容积更大。
