At death, lactic acid builds up to which pH range?

• A. 5-6
• B. 6-7
• C. 4-5
• D. 7-8

Answer: (A)

When oxygen supply stops, cells switch to anaerobic metabolism and produce lactic acid. This lactic acid accumulates faster than the body can buffer it, lowering the tissue pH from its normal slightly alkaline range (about 7.35–7.45) toward more acidic levels. Postmortem, this process drives the pH down into an acidic range, typically around 5–6, reflecting significant lactic acid buildup and acidosis.

The other options describe pH levels that don’t align with the immediate postmortem shift caused by anaerobic glycolysis. A pH around 6–7 would indicate only mild acidity, while 4–5 would be unusually extreme, and 7–8 would be alkaline, which isn’t produced by the lactic acid accumulation after death.

So, lactic acid buildup after death best corresponds to a pH range of 5–6.