Chernow B, Zaloga G, McFadden E, Clapper M, Kotler M, Barton M, Rainey T G
Crit Care Med. 1982 Dec;10(12):848-51. doi: 10.1097/00003246-198212000-00008.
Hypocalcemia is an important metabolic problem in critical care medicine. To determine the frequency of this problem and the patient subsets at risk, a retrospective study of a large series of ICU patients was performed. During the study period, 259 patients were admitted to the ICU, of whom 210 (81%) had a serum calcium (Ca++) measured. Of these 210 patients, 135 (64%) were hypocalcemic (serum Ca++ less than 8.5 mg/dl) and 75 (36%) were normocalcemic. Serum albumin concentration was less than 3.5 g/dl in 70% of the hypocalcemic patients who hd albumin measured, suggesting that the ionized Ca++ concentration may have been normal in many of these patients. On the other hand, 32% of the hypocalcemic patients were alkalotic (pH greater than or equal to 7.45) which indicates that ionized Ca++ levels may have been low because Ca++ binding to protein increases with alkalosis. Gastrointestinal bleeders and postabdominal surgery patients were more likely to have low total serum Ca++ whereas cardiac and neurosurgical patients were more likely to have a normal total serum Ca++ (p less than 0.05). Ionized Ca++ was calculated in 36 of the normocalcemic and 80 of the hypocalcemic patients. The hypocalcemic group had significantly lower ionized Ca++ levels when compared to those of the normocalcemic group (p less than 0.001). Patients with low serum Ca++ values spent a longer time in the ICU (p less than 0.01), had an increased incidence of renal failure and sepsis (p less than 0.01), had an increased mortality rate (p less than 0.001), and received a greater number of blood transfusions (p less than 0.001) than patients in the normocalcemic group. It is concluded that: (1) hypocalcemia is a frequent finding in critically ill patients; (2) determining ionized Ca++ levels is useful because many ICU patients have alterations in both arterial pH and serum albumin levels; (3) hypoalbuminemia, sepsis, red cell transfusions, and renal failure are predisposing factors for hypocalcemia; and (4) hypocalcemic patients do less well clinically than normocalcepatientsmic patients.
低钙血症是重症医学中的一个重要代谢问题。为了确定该问题的发生频率及有风险的患者亚组，我们对一大系列重症监护病房（ICU）患者进行了一项回顾性研究。在研究期间，259例患者入住ICU，其中210例（81%）检测了血清钙（Ca++）。在这210例患者中，135例（64%）为低钙血症（血清Ca++低于8.5mg/dl），75例（36%）为血钙正常。在检测了白蛋白的低钙血症患者中，70%的患者血清白蛋白浓度低于3.5g/dl，这表明这些患者中的许多人离子化Ca++浓度可能正常。另一方面，32%的低钙血症患者存在碱中毒（pH大于或等于7.45），这表明离子化Ca++水平可能较低，因为随着碱中毒，Ca++与蛋白质的结合增加。胃肠道出血患者和腹部手术后患者更易出现血清总Ca++水平降低，而心脏和神经外科患者更易出现血清总Ca++水平正常（p<0.05）。对36例血钙正常患者和80例低钙血症患者计算了离子化Ca++。与血钙正常组相比，低钙血症组的离子化Ca++水平显著更低（p<0.001）。血清Ca++值低的患者在ICU的住院时间更长（p<0.01），肾衰竭和脓毒症的发生率增加（p<0.01），死亡率增加（p<0.001），并且与血钙正常组患者相比，输血次数更多（p<0.001）。得出以下结论：（1）低钙血症在危重症患者中很常见；（2）测定离子化Ca++水平很有用，因为许多ICU患者的动脉pH值和血清白蛋白水平都有改变；（3）低白蛋白血症、脓毒症、红细胞输血和肾衰竭是低钙血症的易感因素；（4）低钙血症患者的临床情况比血钙正常患者差。
