[Analyses of preanalytical issues on samplings and samples].
To obtain "exact" laboratory data which show or reflect the pathophysiological conditions of patients, preanalytical, analytical and postanalytical processes should be checked. However, it is difficult to know the preanalytical situation or out of laboratories. We realize preanalytical issue is one of the weak points in current laboratory medicine. I reported the results of analyses on the issues concerning abnormal laboratory data produced by inadequate handling of samples and sample collection. Five issues are described as follows: 1) The effect of detergents on fecal occult blood test. Immunological methods were affected markedly to moderately by various sanitizers and detergents tested. In collecting feces for immunological fecal occult blood test, contact of feces with toilet flush water dissolving sanitizers should be inhibited. 2) Blood storage and potassium(K) release. Causes of slight elevation of K in serum are sometimes unknown. Addition of injection drugs in vitro showed that various drugs induced K release from erythrocytes. Cold storage of blood is well-known to bring elevation of K level, however, the detailed mechanism is still unknown. We developed a simple method to measure K flux activity of erythrocytes and the decreased activity was shown in patients with chronic renal insufficiency and the aged as well as the aged erythrocytes. 3) Thawed serum and concentration difference. Frozen serum samples were thawed without mixing and various layers contained different concentrations in 60 items tested. Comparing the concentration before freezing, the upper layer contained 1/2 and the bottom 2 times more. T3 and FT4 showed exceptionally smaller difference, significance of which is unknown. 4) Two syringe method in blood collection. Blood samples drawn in the first half and the latter half were comparatively measured for APTT, PT and TT. Blood amount of 1 ml or more showed no differences. TT showed elevation in the first half in 0.5 ml-sample. The effects of local treatment by warming, tapping and congestion were examined. In some cases, tissue factor level elevated by such physical pretreatment. However, in usual blood collection in human, two syringe method is not necessarily employed. 5) Heat-inactivation and cold storage of serum. Preheating sera at 56 degrees C for 30 min reduced markedly the levels of ALT, ALP, CK, ChE, ATIII and alpha 2-PI. In seroimmunology, some complement components are markedly affected and rheumatoid factor of IgM classes was also affected. In about a half of HCV-Ab positive sera, CH50 levels were decreased by the cold storage(cold activation). We reported previously the non-participation of C1q in this phenomenon. In such sera, temperature management is important. Scientific data on the storage and collection of samples should be informed not only to laboratory staffs but to nurses and doctors in order to provide "exact" data.
Yoshida
H
H
Department of Clinical Laboratory Medicine, Fukushima Medical University School of Medicine, Fukushima 960-1247.
D001793:Blood Preservation; D001800:Blood Specimen Collection; D006801:Humans; D009780:Occult Blood; D011188:Potassium; D013048:Specimen Handling; D013696:Temperature
D011188:Potassium