Postmortem Clinical Chemistries Other Flashcards
What are useful matrices in clinal medicine
blood, serum, and plasma
Postmortem limited value
Decomposition
Varying target analyte concentrations
Not super useful
Analytes of value in BLOOD samples
Ketones
Creatinine
Hemoglobin A1C
Tryptase
Ketones
Volatile [GC-HS] analyses
Alcoholics
Ketogenic diets [nutritional ketosis]
Starvation
Independent of chronic alcohol abuse
Pregnancy
Peri-operative diets
Diabetic ketoacidosis
1-5% fatal
1/3 of cases no Hx of diabetes
Creatinine
Stable for ~3 days
Useful for renal function assessment
Trends higher [normal renal function] in certain deaths – probably due to acute renal failure
Blunt force trauma
Intoxication
Fire deaths
Increases with the onset of rigor mortis
Vitreous still go to sample
What does glucose show
Acute state of hyperglycemia – vitreous glucose
Not always available
Not indicator of long term glucose control
How is HbA1C formed
nonenzymatic addition of glucose to hemoglobin
Conc increases with increased blood glucose
Indicator of long term glucose control—-big!
Mean blood conc over 6-8 week period
Relatively stable as opposed to blood glucose
Slight rise in conc over PM interval – no impact of interpretation
Winecker et al study
evaluated postmortem cases of diabetic and non-diabetic decedents
Non-diabetics: mean 5.8 +- 0.3
Diabetics: 12.4 +- 2.8
Some methods inconclusive results
25% of cases
Matrix related
What tube is HbA1C measured
EDTA tubes or NaF tubes study showed no significant difference at any time points
Tryptase
Evaluated tryptase supportive evidence of anaphylactic death
CPR increases level – femoral blood sample preferred
Stability issues
Decline in levels over a 72 hour interval
Interpretation
Clinical cut-off 1 ng/mL [95 percentile upper limit 11.4 ng/mL]
PM femoral blood cut-off: 43 – 53.8 ng/mL
Cardiac blood: 110 ng/mL
Limited studies
