Symptoms of IRIDA (Iron-Refractory Iron Deficiency Anemia)
IRIDA typically presents in childhood with microcytic hypochromic anemia that becomes less severe with age, characterized by remarkably low transferrin saturation (TSAT), low-to-normal serum ferritin, and failure to respond to oral iron therapy. 1
Core Clinical Features
The hallmark symptoms and laboratory findings of IRIDA include:
Hematologic Manifestations
- Microcytic hypochromic anemia - the primary presenting feature 1
- Severity varies: ranges from mild to severe, with tendency to improve with increasing age 1
- Hemoglobin levels remain persistently low despite oral iron supplementation 2, 3
Laboratory Characteristics (Diagnostic Pattern)
- (Very) low transferrin saturation (TSAT) - a remarkably distinctive feature 1
- Low-to-normal serum ferritin when untreated 1
- Note: Some atypical cases may present with hyperferritinemia at initial presentation 4
- Inappropriately elevated serum hepcidin relative to iron status 1, 5
- Elevated hepcidin:TSAT ratio above local upper reference limits 1
- Low serum iron 2
- Elevated erythropoietin levels 2
Clinical Presentation Timeline
- Most commonly presents in childhood (post-natal period through early childhood) 1, 5
- Some cases remain undiagnosed until adulthood 5
- Mean age at diagnosis in case series: approximately 5 years (range 0.7-11.3 years) 3
Treatment Response Pattern (Key Diagnostic Clue)
- Complete or partial refractoriness to oral iron therapy - this is the defining clinical feature that should raise suspicion 1, 3
- Partial response to intravenous iron supplementation 1
- Slow, incomplete correction of anemia even with parenteral iron 5
Additional Clinical Considerations
Symptoms in Specific Populations
In pregnant women with IRIDA, the phenotype includes 2:
- Lower hemoglobin and red blood cell counts compared to typical iron deficiency
- Significantly elevated hepcidin (9.47 ± 2.75 ng/mL)
- Elevated erythropoietin (4.58 ± 4.07 µ/mL)
- Prevalence of approximately 2.15% among pregnant women with moderate to severe microcytosis
What IRIDA Does NOT Typically Cause
Unlike other genetic iron disorders, IRIDA patients do not typically present with 1:
- Photosensitivity
- Neurological disease
- Hemolysis
- Isolated ataxia
- Significant systemic symptoms beyond anemia-related fatigue
Critical Diagnostic Pitfall
The key to recognizing IRIDA is identifying the paradox: microcytic anemia with low iron parameters BUT inappropriately elevated hepcidin levels and failure to respond to oral iron. 1, 5 This distinguishes it from common acquired iron deficiency anemia, where hepcidin should be low or undetectable. Other causes of oral iron refractoriness (autoimmune atrophic gastritis, H. pylori infection, celiac disease) must be excluded before considering IRIDA 1.
The diagnosis should be suspected when a patient presents with unexplained microcytic anemia, low TSAT, normal or reduced ferritin, and documented non-response or partial response to oral iron therapy 1.