A 62-year-old man with a history of alcohol use disorder and severe cirrhosis is admitted to the hospital with generalized weakness. His vital signs are within normal limits. Physical examination reveals temporal wasting, scleral icterus, and a distended abdomen with shifting dullness.
Laboratory studies show:
| Test | Result | Reference Range |
|---|---|---|
| Sodium | 132 mEq/L | 135-145 mEq/L |
| Potassium | 3.8 mEq/L | 3.5-5.0 mEq/L |
| Chloride | 100 mEq/L | 98-106 mEq/L |
| Bicarbonate | 22 mEq/L | 22-28 mEq/L |
| Blood urea nitrogen | 12 mg/dL | 8-20 mg/dL |
| Creatinine | 0.9 mg/dL | 0.7-1.3 mg/dL |
| Total calcium | 7.2 mg/dL | 8.4-10.2 mg/dL |
| Albumin | 2.0 g/dL | 3.5-5.0 g/dL |
Based on these laboratory results, what is this patient's corrected serum calcium concentration in mg/dL?
Cevap: 8.8 mg/dL
Cevap
8.8
The correct calculation yields 8.8 mg/dL. Approximately 40-45% of calcium in the blood is bound to serum proteins, primarily albumin. When serum albumin is low, the measured total calcium will also be low, but the physiologically active ionized calcium level usually remains normal. To accurately assess the calcium status in a patient with hypoalbuminemia, the total calcium must be corrected. The standard formula is: . Applying this to the patient's values: mg/dL. This reveals that the patient's calcium level is actually within the normal reference range (8.4-10.2 mg/dL), representing pseudohypocalcemia.
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Correcting total serum calcium in the setting of hypoalbuminemia is essential to avoid misdiagnosing hypocalcemia, as roughly 40-45% of serum calcium is bound to albumin.