Does a transferrin saturation (TSAT) of 33% and a ferritin level of 195 indicate iron overload and cause an elevated mean corpuscular volume (MCV)?

Iron Status Interpretation with TSAT 33% and Ferritin 195

A transferrin saturation (TSAT) of 33% and ferritin level of 195 ng/mL do not indicate iron overload and will not cause an elevated mean corpuscular volume (MCV). 1

Understanding Iron Parameters and Their Interpretation

Normal Iron Parameters

• TSAT of 33% is within normal range, as normal transferrin is typically not more than 50% saturated with iron 1
• Ferritin level of 195 ng/mL is also within normal range, as values between 100-300 ng/mL are generally considered normal in adults 1
• These values represent adequate iron stores without evidence of iron overload 1

Defining Iron Overload

• Iron overload is typically characterized by:
  • TSAT levels greater than 45-50% 1
  • Ferritin levels persistently above 500-1000 ng/mL 1
  • In historical cases of severe iron overload, patients had ferritin levels exceeding 7,500 ng/mL and TSAT greater than 88% 1

Impact on MCV

• The provided iron parameters (TSAT 33%, ferritin 195) would not cause an elevated MCV 1
• MCV elevation is typically associated with:
  • B12 or folate deficiency
  • Alcohol consumption
  • Liver disease
  • Certain medications
  • Myelodysplastic syndromes
  • NOT with normal iron parameters 1

Clinical Implications

When to Suspect Iron Overload

• Iron overload should be considered when:
  • TSAT is persistently above 45% 1
  • Ferritin is consistently elevated above 500-1000 ng/mL 1
  • There are clinical signs of end-organ damage (liver, heart, pancreas) 1
  • Genetic testing confirms hemochromatosis (C282Y homozygosity) 1

Diagnostic Pitfalls to Avoid

• Ferritin is an acute phase reactant and can be elevated in:
  • Inflammation
  • Infection
  • Malignancy
  • Liver disease
  • Without representing true iron overload 1, 2
• TSAT can be affected by:
  • Timing of blood draw (diurnal variation)
  • Recent iron supplementation
  • Inflammatory states 1, 3

Conclusion

The iron parameters provided (TSAT 33%, ferritin 195 ng/mL) represent normal iron status without evidence of iron overload 1. These values would not cause an elevated MCV, as MCV elevation is typically associated with other clinical conditions rather than normal iron parameters 1.