Vallance S
Wolfson Research Laboratories, Queen Elizabeth Medical Centre, Edgbaston, Birmingham, UK.
Br J Surg. 1988 Apr;75(4):366-70. doi: 10.1002/bjs.1800750424.
Postoperative changes in plasma and buffy layer (BL) vitamin C were studied in 107 patients receiving either 0 (37 patients), 100 mg (33 patients) or 500 mg (37 patients) vitamin C supplements daily. In patients receiving no supplement plasma vitamin C concentrations had fallen (mean 33 per cent) by the first postoperative day and thereafter changed little. The falls occurred irrespective of initial plasma concentration, were greater the higher the initial concentration, but tended to be proportional to the length of operation. In patients given supplements this loss of vitamin C was evident but modified, and from the second postoperative day the response to the supplements was as would have been expected in non-operated subjects. The most probable explanation for the loss of vitamin C from plasma was an increased urinary excretion during operation. Changes in BL vitamin C concentrations were studied in relation to changes in leucocyte and platelet counts. The previously reported postoperative falls in BL vitamin C were found to be the result of a major artefact in the methods routinely used for BL vitamin C estimation, caused by changes in the leucocyte and platelet populations, most importantly the platelet to leucocyte ratio. No true demand for vitamin C, as measured from the buffy layer cells, was evident.
对107例每天分别补充0毫克（37例患者）、100毫克（33例患者）或500毫克（37例患者）维生素C的患者，研究了术后血浆和血沉棕黄层（BL）维生素C的变化。在未补充维生素C的患者中，术后第一天血浆维生素C浓度就已下降（平均下降33%），此后变化不大。这种下降与初始血浆浓度无关，初始浓度越高下降幅度越大，但往往与手术时间长短成正比。在补充维生素C的患者中，维生素C的这种流失很明显但有所改变，从术后第二天起，对补充剂的反应与未手术患者预期的反应相同。血浆中维生素C流失的最可能原因是手术期间尿排泄增加。研究了BL维生素C浓度变化与白细胞和血小板计数变化的关系。发现先前报道的术后BL维生素C下降是常规用于BL维生素C测定方法中一个主要假象的结果，该假象由白细胞和血小板数量变化引起，最重要的是血小板与白细胞的比例。从血沉棕黄层细胞测定来看，没有明显的对维生素C的真正需求。
