What does a percentage iron saturation of 51 indicate?

Interpretation of Iron Saturation of 51%

A transferrin saturation of 51% indicates early iron overload and warrants further evaluation for potential hemochromatosis or other iron overload disorders. This level exceeds the normal range and suggests increased iron stores that require additional testing to determine the underlying cause.

Understanding Transferrin Saturation

• Transferrin saturation (TSAT) reflects iron that is readily available for erythropoiesis, calculated as serum iron multiplied by 100 and divided by total iron binding capacity (TIBC) 1
• A TSAT of 50% indicates that half of the transferrin binding sites are occupied by iron 1
• Normal TSAT is typically below 45%, with values above this threshold suggesting potential iron overload 1

Clinical Significance of 51% Iron Saturation

• According to the American College of Physicians guidelines, a TSAT greater than 55% suggests an increased risk for hereditary hemochromatosis 1
• At 51%, this value is approaching this threshold and warrants clinical attention 1
• This level is significantly higher than the 20% cutoff used to identify iron deficiency, indicating adequate or excessive iron availability 1

Recommended Evaluation

• Measure serum ferritin to complement TSAT findings 1
  • Ferritin >200 μg/mL in women or >300 μg/mL in men, along with elevated TSAT, strongly suggests iron overload 1
• Consider genetic testing for HFE mutations (C282Y and H63D) to evaluate for hereditary hemochromatosis 1, 2
• If genetic testing is negative but iron overload is still suspected, evaluate for secondary causes 2

Potential Causes to Consider

• Primary hemochromatosis (genetic disorder of iron metabolism) 1
• Secondary iron overload conditions:
  • Hematologic disorders (thalassemia, myelodysplastic syndrome, sideroblastic anemia) 2
  • Chronic liver disease, particularly with alcohol consumption 1, 2
  • Metabolic syndrome components (obesity, hyperlipidemia, abnormal glucose metabolism) 3

Important Caveats

• A single elevated TSAT measurement should be confirmed with repeat testing due to diurnal variations 1
• TSAT can be elevated in Asian and Pacific Islander populations without HFE mutations 1
• TSAT alone is not perfectly specific for iron overload; serum ferritin should always be measured concurrently 1
• Some patients with elevated TSAT may have normal iron stores, so clinical correlation is essential 1

Next Steps

• If both TSAT and ferritin are elevated, consider MRI to quantify hepatic iron concentration, especially if the cause remains unclear 1
• In patients with confirmed iron overload, evaluate for end-organ damage, particularly liver, heart, and pancreatic involvement 1
• Phlebotomy is the treatment of choice for confirmed iron overload disorders 1