Lactate Gap: A Diagnostic Support in Severe Metabolic Acidosis of Unknown Origin

Table 1

Laboratory values.

Measurement	Arrival at ICU	8 hours later	Reference values
Lactate, blood (POCT)	Higher than upper measuring limit	10.7	<2 mmol/L
Lactate, plasma	3.8	1.3	<2 mmol/L
pH	6.77	7.37	7.37–7.45
pCO2	1.5	6.9	4.7–6.0 kPa
Bicarbonate	2	29	22–27 mmol/L
Base excess	−30	4	0 ± 3
Potassium	7.4	4.3	3.5–5.0 mmol/L
Anion gap^1	41	17	3–9 mmol/L
Osmolality	426	306	280–300 mOsmol/kg H2O
Osmolar gap^2	106	2	<10 mOsmol/kg H2O

Measured with a Radiometer ABL800 FLEX point-of-care whole blood analyzer (bicarbonate and base excess are calculated). Measured with a Vitros 5.1-plasma laboratory analyzer. ¹Anion gap = ([Na⁺] + [K⁺]) − ([Cl⁻] + [HCO₃⁻]). ²Osmolar gap = measured osmolality − (1.86 × [Na⁺] + [glucose] + [urea]/0.93).