Albumin-adjusted calcium is not suitable for diagnosis of hyper- and hypocalcemia in the critically ill.

OBJECTIVE

To evaluate whether calcium adjusted for albumin can be used to monitor calcium homeostasis in critically ill patients.

DESIGN

Prospective single-single center observational study.

SETTING

Clinical laboratory and critical care unit of a regional teaching hospital.

PATIENTS

Fifty-three paired samples were from 36 patients requiring intensive care treatment.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Total calcium, albumin-adjusted calcium, and ionized calcium were measured in critically ill patients during an 8-wk period. Calcium was adjusted for albumin using the formula that is most frequently used in The Netherlands. Using ionized calcium as the gold standard, albumin-adjusted calcium overestimated hypercalcemia and totally missed hypocalcemia. The same seemed to be true for other formulas used for albumin or protein adjustment of calcium concentrations.

CONCLUSIONS

Albumin-adjusted calcium cannot be used in an intensive care setting to monitor reliably the calcium levels in critically ill patients and should be replaced by measurement of ionized calcium.