What effect does low albumin have on calcium levels?

Low albumin levels can lead to a situation where the total serum calcium appears lower than it actually is, a phenomenon due to the binding nature of calcium in the blood. Calcium in the serum exists in two forms: free (ionized) calcium, which is biologically active, and bound calcium, primarily to proteins like albumin.

When albumin levels drop, as often seen in conditions such as liver disease, nephrotic syndrome, or malnutrition, there are fewer proteins available to bind calcium. Consequently, while the total calcium measurement reflects this decrease in binding, it doesn't necessarily mean that the free, active calcium is truly low.

This means that with low albumin, even if the total serum calcium measurement is reported as low, it may not indicate a deficiency in the biologically active calcium. This creates a situation where calcium levels appear lower than they are, thus leading to the interpretation that calcium falsely appears low in the context of reduced albumin levels.