## 4 Discussion  
Ketone bodies (AcAc, BHB and Ac) are secondary compounds of lipid metabolism and are used as an energy substrate when glucose is insufficient or inaccessible. Thus, when blood glucose levels are low, free fatty acids are used as an alternative source of energy through the process of ketogenesis which takes place exclusively in the liver. AcAc is formed by the beta-oxidation of fatty acids and can be reduced to BHB by the enzyme 3-hydroxybutyrate dehydrogenase in a reversible reaction depending on the NADH/NAD+ ratio [13; 15]. Ac is formed by spontaneous decay-doxidation of AcAc and is generally considered to be of minor metabolic importance [15; 16; 17]. IPA is another compound related to the ketosis state, and it is observed in many conditions characterized by ketosis and increased NADH/NAD+ ratio [17; 18]. Ketone bodies are converted to acetyl-CoA in hepatocyte mitochondria, especially the perivenous hepatocytes, and thus used as an energy substrate for the Krebs cycle [13]. In the present study, we determined BHB concentration in various body fluids using two methods with different principles and applicability. The obtained results were similar to those reported in the literature [6; 9; 22; 23; 24]. We chose two different threshold values for affirming ketoacidosis depending on the method of BHB determination. When using the handheld multifunctional \(\beta\)-analyzer we applied the threshold values most used in the literature [9; 25; 26; 27]. For evaluating ketone bodies with an MAK041 kit we chose lower diagnostic values according to the results obtained by other researchers using the same diagnostic kit [28]. The BHB values determined were not similar in the four collection sites, but the concentrations quantified in VH, CSF occ and peripheral blood significantly correlated with each other (\(p<0.001\)). The correlation coefficients we obtained demonstrate the reliability of \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Variable** & **Pearson r** & **r\({}^{2}\)** & **t** & \(p\) & **No of Cases** \\ \hline VH BHB-CSF occ BHB & 0.945 & 0.89 & 20.78 & \textless{}0.000001 & 53 \\ VH BHB-CSF L BHB & 0.55 & 0.29 & 3.07 & 0.0056 & 24 \\ CSF occ BHB-CSF L BHB & 0.56 & 0.32 & 3.21 & 0.004 & 24 \\ VH BHB-peripheral blood BHB & 0.76 & 0.58 & 6.75 & \textless{}0.000001 & 35 \\ CSF occ BHB-peripheral blood BHB & 0.81 & 0.66 & 8.01 & \textless{}0.0000001 & 35 \\ CSF L BHB-peripheral blood BHB & 0.54 & 0.29 & 2.99 & 0.0067 & 24 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Correlations between VH BHB, CSF occ BHB, CSF L BHB and peripheral blood BHB. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**BHB from:** & **Mean 1** & **Mean 2** & **Test t** & **gl** & \(p\) & **N1** & **N2** & **SD 1** & **SD 2** \\ \hline VH & 0.3687 & 0.3906 & 0.58 & 51 & 0.56 & 12 & 41 & 0.1345 & 0.1130 \\ \hline CSF occ & 0.3245 & 0.3451 & 0.50 & 51 & 0.62 & 12 & 41 & 0.1415 & 0.1255 \\ \hline CSF L & 0.2103 & 0.1831 & 1.11 & 22 & 0.28 & 10 & 14 & 0.0636 & 0.0559 \\ \hline Peripheral blood & 2.1077 & 2.7409 & 0.80 & 33 & 0.43 & 12 & 23 & 1.7495 & 2.5126 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: BHB according to presence/absence of known DM antemportem/postmortem. both methods as well as the stability of the biochemical marker in all three types of collected fluids. Therefore, our results are consistent with other research and allow us to affirm that any of the three types of body fluids can be used for post-mortem BHB determination for the diagnosis of ketoacidosis [5; 29]. The few determinations of BHB levels in CSF performed over time have led to divergent opinions, with some researchers suggesting that BHB should be quantified post-mortem only in VH and peripheral blood [30]. In contrast, other investigators claimed that the post-mortem value of BHB in CSF would be closer to the true value compared to that identified in VH [23] without stating the collection site, whether suboccipital or lumbar. Two studies published by [PERSON] et al.