What does a ferritin level of 173 ng/mL indicate in a 75-year-old woman?

Ferritin 173 ng/mL in a 75-Year-Old Woman: Interpretation

A ferritin level of 173 ng/mL in a 75-year-old woman is within the normal range and does not indicate iron deficiency, though it requires clinical context to rule out inflammation or other conditions that may elevate ferritin.

Understanding Ferritin Reference Ranges

Age and Sex-Specific Considerations

• In elderly women, ferritin levels naturally increase after menopause, with geometric means around 60 μg/L in healthy elderly females, though individual variation is substantial 1.
• Research demonstrates that women after age 50 show an abrupt increase in ferritin levels compared to premenopausal women, where levels typically remain low (around 26.4 ng/mL) 2.
• The average serum ferritin concentration in the general U.S. population is approximately 43 μg/L for women, but this includes all age groups 3.

Clinical Thresholds for Iron Deficiency

Without inflammation present:

• Ferritin <30 ng/mL defines iron deficiency 4
• Ferritin <15 ng/mL indicates absolute iron deficiency with depleted iron stores 4, 5
• The most recent AGA guidelines recommend using ferritin <45 ng/mL as the optimal threshold for diagnosing iron deficiency in anemic patients, balancing sensitivity (85%) and specificity (92%) 6, 7, 8

With inflammation present:

• The lower limit of normal ferritin increases to 100 ng/mL when inflammation is present 4
• Ferritin is an acute-phase reactant and can be falsely elevated by chronic infection, inflammation, liver disease, malignancy, or chronic kidney disease 3, 9, 5

Interpretation of 173 ng/mL

This Level Indicates:

• Normal iron stores in the absence of inflammatory conditions 4
• No iron deficiency by any standard diagnostic criteria 5, 6, 7
• A value well above thresholds used to diagnose iron deficiency even in the presence of inflammation 4

Important Clinical Context Required:

Check for inflammatory conditions:

• Measure C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) to assess for inflammation 4
• If inflammation is present, ferritin 173 ng/mL still suggests adequate iron stores, as it exceeds the 100 ng/mL threshold used in inflammatory states 4

Assess for conditions that elevate ferritin:

• Chronic liver disease (hepatitis, cirrhosis)
• Malignancy
• Chronic kidney disease
• Metabolic syndrome or dysmetabolic iron overload syndrome (DIOS)
• Inflammatory conditions (rheumatoid arthritis, inflammatory bowel disease) 3, 5

Consider transferrin saturation (TSAT):

• If TSAT is <16-20% despite ferritin 173 ng/mL, this suggests functional iron deficiency or anemia of chronic disease 4
• TSAT >20% with ferritin 173 ng/mL confirms adequate iron availability for erythropoiesis 9

Clinical Pitfalls to Avoid

• Do not diagnose iron deficiency based solely on symptoms when ferritin is 173 ng/mL without additional confirmatory testing 5, 7
• Do not initiate iron supplementation at this ferritin level unless transferrin saturation is low and functional iron deficiency is documented 4, 9
• Do not overlook other causes of anemia if present, including vitamin B12/folate deficiency, chronic kidney disease, or medication effects 4, 10
• In elderly patients, values considered normal in middle-aged populations do not rule out sideropenia, but 173 ng/mL is well above concerning thresholds even in advanced age 11

Recommended Next Steps

If the patient is asymptomatic with normal hemoglobin:

• No further iron-related workup is needed 5, 7
• Ferritin 173 ng/mL represents adequate iron stores 4, 1

If anemia is present:

• Obtain complete blood count with red cell indices (MCV, MCH) 5
• Measure transferrin saturation to assess iron availability 4
• Check inflammatory markers (CRP, ESR) 4
• Evaluate for other causes of anemia beyond iron deficiency 10

If chronic disease is suspected:

• Ferritin >100 ng/mL with TSAT <16% suggests anemia of chronic disease 4
• Address the underlying inflammatory or chronic condition as the primary intervention 4