Prealbumin (Thyroxine Binding Prealbumin / Transthyretin)

The Prealbumin test, also known as Transthyretin or Thyroxine Binding Prealbumin, measures the level of prealbumin in the blood. Prealbumin is a protein produced primarily by the liver and plays a role in transporting thyroid hormones (particularly thyroxine) and vitamin A. This test is often used to evaluate nutritional status and monitor protein-calorie malnutrition.

1. What Is Prealbumin?

• Prealbumin is a transport protein that binds and carries thyroxine (T4) and retinol-binding protein (which carries vitamin A).

• It has a short half-life (2–3 days), making it a sensitive marker for recent nutritional changes.

• Although its name suggests a relation to albumin, it is a distinct protein with different functions.

2. Why Is the Prealbumin Test Performed?

This test is used to:

• Evaluate nutritional status, especially in hospitalized patients or those receiving tube or IV feeding.

• Monitor response to nutritional therapy in malnourished individuals.

• Assess liver function or detect liver damage.

• Help differentiate causes of low serum protein levels.

3. Prealbumin Reference Range

• Normal range: 15 – 36 mg/dL (may vary by lab)

• Lower levels may indicate malnutrition or liver disease.

• Higher levels are less common but may be seen in certain inflammatory or renal conditions.

4. Interpreting Prealbumin Results

🔹 Low Prealbumin:

• Suggests protein-calorie malnutrition or inadequate intake.

• Can also be due to liver disease, inflammation, burns, or trauma.

🔹 High Prealbumin:

• May be seen in chronic kidney disease, steroid use, or dehydration.

• Less commonly used to diagnose disease than low values.

5. What Can Affect Prealbumin Levels?

• Recent dietary intake or nutritional supplementation

• Liver function (prealbumin is synthesized in the liver)

• Inflammatory states (prealbumin is a negative acute phase reactant)

• Kidney function and protein-losing conditions

6. How Is the Test Performed?

• A blood sample is drawn from a vein.

• No special preparation is required, but the test is often interpreted with other labs (e.g., CRP, albumin, liver panel).

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have symptoms of malnutrition, unexplained weight loss, or poor wound healing.

• Are being monitored for nutrition support or liver/kidney disease.

• Have abnormal prealbumin levels that require further evaluation.

🔹 Key Takeaways

✅ Prealbumin is a useful short-term marker for nutritional status and protein metabolism.

✅ Low levels may reflect malnutrition, liver dysfunction, or inflammation.

✅ Regular monitoring can help guide nutrition therapy and recovery in clinical settings.