Serum ionized calcium in acute pancreatitis.

Measurement of serum ionized calcium was performed daily for 7 days after admission in 8 consecutive patients with acute pancreatitis. The results support the findings of our previous study that the most common cause of the low serum calcium often found in patients with this disease is a low serum albumin; when correction of serum calcium is made for hypo-albuminanemia, most patients are found to be normocalcaemic. The occasional hypocalcaemia as shown by the 'corrected' serum calcium or by serum ionized calcium measurement is usually mild and transient, indicating that the normal homoeostatic mechanisms of the body can efficiently maintain the physiologically active fraction of the serum calcium within, or close to, the normal range. These findings explain the rarity of overt and subclinical tetany in acute pancreatitis. This study has shown that correction of serum calcium for albumin provides similar information to the direct measurement of serum ionized calcium. The value of 'apparent' hypocalcemia in assessing severity of acute pancreatitis requires reappraisal, while greater attention should be directed towards the investigation and management of hypoalbuminaemia in this disease.