What the numbers really show
Both albumin and prealbumin (transthyretin) are negative acute-phase proteins. During inflammation the liver reprioritizes protein synthesis toward positive acute-phase proteins such as C-reactive protein, and production of albumin and prealbumin falls; capillary leak also moves albumin out of the bloodstream. On day 1 her C-reactive protein is 148 mg/L, showing intense inflammation from pneumonia, so low albumin (2.9 g/dL) and low prealbumin (11 mg/dL) mainly reflect that inflammation. These proteins track the inflammatory response, so they cannot judge whether her feeding is working.
Why albumin cannot reflect 3 days of feeding
Albumin has a long half-life of about 3 weeks, so a change over 3 days cannot reflect what she has been fed. It is also sensitive to fluid status; intravenous fluids and capillary leak dilute or redistribute it. The fall from 2.9 to 2.7 g/dL is therefore expected in an acutely ill client and does not mean the feeding is failing. Prealbumin has a shorter half-life, and its small rise from 11 to 13 mg/dL parallels the fall in C-reactive protein from 148 to 62 mg/L. It shows that inflammation is settling, not that protein stores have been rebuilt.
| Marker | Day 1 | Day 4 | Best explanation |
|---|
| Albumin | 2.9 g/dL | 2.7 g/dL | Long half-life; affected by inflammation and fluid shifts |
| Prealbumin | 11 mg/dL | 13 mg/dL | Rises as inflammation settles |
| C-reactive protein | 148 mg/L | 62 mg/L | Inflammation improving but still far above normal |
Why the other interpretations are wrong
Saying the feeding is inadequate and must be increased acts on a marker that cannot answer the question, and increasing the rate in a refeeding-risk client could be harmful. Claiming the rising prealbumin proves repletion over-reads a small change that is explained by falling inflammation. Saying albumin is now the better marker ignores that her C-reactive protein is still more than ten times the upper limit and that albumin's half-life has not changed. Watch out! A student who equates low albumin with malnutrition is applying an outdated idea; current practice does not use these proteins alone to diagnose or monitor malnutrition.
What the nurse uses instead
Adequacy of nutrition support is judged by actual intake compared with the prescribed amount, serial body weight, and physical findings such as muscle and fat loss, fluid status, and functional strength. Key point! Interpret albumin and prealbumin together with C-reactive protein, and judge the feeding plan by intake, weight, and the physical examination.