10 mm, including centrifuge time, after venesection. The concentration of 3-OHBA was stable both at room temperature and in an ice bath for 6 h after drawing.
tion by enzyme-linked immunosorbent assay and purification from normal urine. J Immunol Methods 1991;141:97-104.
Tardy’ Bulle’ Lionel p1.j12 Jean-Fran#{231}ois Cordier8 Philippe Devilier1 de Biochim. Fred#{233}rique Christianne
‘Lab.
H#{244}pitalCardiovasc. et Pneumol. Louis Pradel and “ Service de Broncho-Pneumol. 59 Blvd. Pinel 69394 Lyon Cedar, France 2Ce d’Immunol. et de Biol. Parasitaire Unite Mixte INSERM U167-CNRS 624, Institut Pasteur 59019 Lile Cedar, France
Stability of Acetoacetat. Venesection
after
To the Editor: Serum or pisanla concentrations of acetoacetate (AcAc) and 3-hydroxybutyrate (3-OHBA) are frequently measured for evaluation of the metabolic state in patients with diabetes mellitus. Several methods for the determination of AcAc and 3-OHBA have been developed (1-5). Eckfeldt et al have pointed out an error in calibration of a 3-OHBA enzymatic assay caused by incorrect preparation of the standard (6, 7). Mellanby and Williamson reported that AcAc is unstable at 37#{176}C
(8),
and
Price
et
al.
observed
that
plasma
AcAc concentration decreased to 1 day (4). However, little attention has been paid to the stability of these concentrations after venesection. Therefore, we examined the effects of variations in time and temperature until separation of serum on the concentrations of AcAc in serum. Venous blood was collected from fasting subjects in the morning into plastic tubes and kept at room temperature (26 ± 1.5 #{176}C) or in an ice bath until separation of serum. Immediately after separation of serum, we measured concentrations of AcAc and 3-OHBA in duplicate analysis by using the enzymatic method reported by Harano et al. (1) with a Model 7050 automated analyzer (Hitachi Co., Tokyo, Japan). Initial concentrations of AcAc and 3-OHRA were determined within 10 mm, including centrifuge time, after venesection. The concentration of 3-OHBA was stable both at room temperature and in an ice bath for 6 h after drawing blood (Figure 1). However, we observed a significant decrease in AcAc concentration early as
at room
temperature
as
1 h after drawing blood (P 1 h after venesection.
References 1. Harano
levels 1985;151:177-83. 2. Li PK, Lee Schaefer
100
and
0
50
E
50 ..
....
0
whole
blood.
KGMM. A kinetic spectrophotometric assay for rapid determination of acetoacetate in blood. Clin Chem 1977;23:1893-7. 5. McMurray CH, Blanchflower WJ, Rice DA. Automated kinetic method for D-3hydroxybutyrate in plasma or serum. Clin Chem 1984;30:421-5. 6. Eckfeldt JH, Leiendecker-Foster C, Kersfaw MJ. Calibration of 3-hydroxybutyrate assays [Letter]. Clin Chem 1984;30: 1116. 7. Eckfeldt ,JH, Leiendecker-Foster C, Kersfaw MJ. Error in calibration of 3-hydroxybutyrate assay [Letter]. Am J Clin Pathol 1984;81:273-4. 8. Mellanby J, Williamson DH. Aeetoacetate. In: Bergmeyer HU, ed. Methods of enzymatic analysis, 2nd ed. New York and London: Academic Press, 1974:1840-3.
Hachiro Yamanishi Shigeru lyama Yoshihisa Yamaguchi Nobuyuki Amino Central Osaka
Lab. Univ.
for Clin.
Invest.
Hasp.
Fukushima ma-ku 553, Japan
TIME
(hour)
3-OHBA
300 -3
200
\
#{149}
200
describe exactly how patients were divided into the two main groups: cerebrovascular pathology and other neurological disease. They also do not adequately describe the criteria used to further subdivide patients. This is
0
E
100
100 #{149}...#{149}-..#{149}......
0 0
2 TIME
4
Fig. 1. StabIlity of AcAc and 3-OHBA bath ( ) after venesection
CHEMISTRY,
6
(hour)
concentrations
Vol. 39, No.5,1993
0
0
In
The authors of the recent paper on the diagnostic significance of methemoglobin (MetHb) in cerebrospinal fluid (CSF) conclude that spectrophotometric analysis of CSF is necessary for all samples (1). I strongly disagree with their conclusion. They failed to
(hour)
3-OHBA
300
Determinations Fluid Have Low
To the Editor:
0 TIME
CUNICAL
in
.....
S..-..
..#{149}
920
3-hydroxybutyrate
Clin Chem 1983;29:319-21. 4. Price CP, Lloyd B, Albert.i
Methemogiobin Cerebrospinal Clinical Utility
-I
\
\
MH,
100
-3 0
MacGillivray
Siegel
Clin Chem 1980;26:1713-7. 3. Cosmi G, Di Corcia A, Samperi R, Vinci G. Gas-chromatographic measurement of 3-hydroxybutyrate and lactate in plasma
Fukushi Osaka
AcAc
PA,
JT,
JH. Direct, fixed-time kinetic assays for $-hydroxybutyrate and acetoacetate with a centrifugal analyzer or a computer-backed spectrophotometer.
1-1-50
AcAc
Y, Ohtsuki M, Ida M, Kojima H, M, Okanishi T, et aL Direct autoassay method for serum or urine of ketone bodies. Clin Chim Acta
Harada mated
2
4
TIME
(hour)
at room temperature
6 (-)
ana
in an ice
an important point, because readers cannot ascertain true sensitivity and specificity of the CSF MetHb assay. In
