What is the significance of a total calcium level of 1.91 millimoles per liter with an albumin level of 27 grams per liter, indicating potential hypocalcemia with hypoalbuminemia?

From the Guidelines

The adjusted calcium level of 1.91 mmol/L with an albumin of 27 g/L indicates hypocalcemia that requires treatment, and I recommend administering calcium chloride to correct hypocalcaemia as per the latest guidelines 1. The normal adjusted calcium range is typically 2.20-2.60 mmol/L, so this value represents a significant deficiency. The low albumin level has been accounted for in the adjusted calcium calculation, confirming true hypocalcemia rather than a laboratory artifact. Patients may experience symptoms including paresthesias, muscle cramps, tetany, seizures, and cardiac arrhythmias. Ongoing monitoring of calcium levels is essential, with a target of achieving low-normal calcium levels. The underlying cause of hypocalcemia should also be investigated, including checking parathyroid hormone levels, vitamin D status, renal function, and magnesium levels, as these may influence treatment approach. It is crucial to maintain ionised calcium levels within the normal range, especially during massive transfusion, as hypocalcaemia can predict mortality and the need for multiple transfusions 1. However, the most recent guideline recommends the administration of calcium chloride to correct hypocalcaemia 1, which should be the preferred treatment approach in this case. Key considerations in treatment include:

• Administering calcium chloride to correct hypocalcaemia
• Monitoring ionised calcium levels
• Investigating the underlying cause of hypocalcemia
• Maintaining low-normal calcium levels to prevent symptoms and complications.

From the FDA Drug Label

1. 3 Pharmacokinetics ... About 50% of total serum calcium is in the ionized form and represents the biologically active part. 8% to 10% serum calcium is bound to organic and inorganic acid and approximately 40% is protein-bound (primarily to albumin) The patient's adjusted calcium level is 1.91 mmol/L with an albumin level of 27 g/L.

• To determine if this is within a normal range, we need to consider the ionized calcium level, which is the biologically active part of calcium.
• However, the provided information does not include the ionized calcium level, only the adjusted calcium level.
• The FDA drug label does not provide a direct correlation between adjusted calcium and ionized calcium levels or a specific normal range for adjusted calcium.
• Given the information provided and the lack of direct correlation, no conclusion can be drawn about the patient's calcium level being within a normal range or not 2.

From the Research

Adjusted Calcium Levels

• The given adjusted calcium level is 1.91 mm per liter with an albumin level of 27 g per liter.
• According to the study 3, the use of albumin-adjusted calcium measurements is commonly recommended, but with little empirical evidence to support the practice.
• The study 3 found that unadjusted total calcium had a stronger correlation with ionized calcium than the commonly used simplified Payne formula, especially in the presence of hypoalbuminemia (albumin level <30 g/L).

Comparison with Studies

• The study 4 proposed an alternative formula for correcting total calcium levels into ionized serum calcium values, which took into account serum protein and albumin levels.
• The study 5 derived a local adjusted calcium equation and found that adjusted calcium cutoffs differed markedly from total calcium cutoffs, allowing for more accurate assessment of severe hypo- and hypercalcemia.
• The study 6 discussed the diagnosis and management of hypocalcemia, emphasizing the importance of correct management and treatment.
• The study 7 suggested that the use of adjustment formulas for total calcium should be abandoned in clinical practice, as unadjusted total calcium had superior diagnostic accuracy, especially in patients with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2.

Clinical Implications

• The adjusted calcium level of 1.91 mm per liter may not accurately reflect the patient's calcium status, especially given the low albumin level of 27 g per liter.
• The studies 3 and 7 suggest that unadjusted total calcium may be a more reliable indicator of calcium status, particularly in patients with hypoalbuminemia.
• Further evaluation and consideration of the patient's overall clinical condition are necessary to determine the appropriate course of action, as discussed in the study 6.