Diabetic ketoacidosis

Monitoring progress

Capillary BG

Monitor hourly (cross-check every 2 or 4 h against laboratory venous glucose)

Laboratory tests

Electrolytes, urea, BG and blood gases should be repeated every 2–4 h until acidosis is reversed

Sodium and osmolality

Despite the depletion of total body sodium in DKA, the elevated osmolality in the hyperglycemic state results in a dilutional effect on the measured sodium

Corrected sodium can be calculated from

[This calculation may be useful when concerns arise with abnormal measured sodium levels]

Serum sodium often rises as the BG falls. Theoretically, sodium should rise by 2 mmol for every 5.5 mmol fall in BG, resulting in a slower fall in osmolality
Serum osmolality can be measured directly or calculated from

Serum osmolality (mOsm) = 2 x (Na + K) + BG (mmol)

[Retrospectively a fall of serum osmolality >3 mOsm/kg per hour has been suggested as a risk factor in cerebral edema although the evidence is weak]

A fall in serum sodium has been noted in a number of studies as one of the few laboratory correlates of impending cerebral edema

If serum sodium fails to rise, and particularly if it falls, a careful re-evaluation of the fluid replacement is required. Consider increasing the concentration of sodium chloride and observe with increased vigilance for signs of cerebral edema
An initial serum sodium >150 mmol/l might prompt an even slower rehydration rate than 48 h

Potassium

The potassium infusion should be titrated to maintain serum potassium within the laboratory normal range

Urine output

If this is inadequate (< 1.5 ml/kg/h) the cause must be sought (e.g. acute renal failure, continuing shock, urinary obstruction, bladder retention). If fluid retention is occurring there is some evidence that a single dose of a loop diuretic might be helpful in promoting water diuresis

Complications