Why iron metabolism is investigated
Iron metabolism parameters are ordered not only for overt iron-deficiency anemia (IDA), but also when vitamin B12-deficiency anemia is suspected — to rule out a combined (polydeficient) condition.
This is clinically important: in classical vitamin B12-deficiency anemia, serum iron and ferritin are typically elevated. However, if the patient has malabsorption syndrome, a combined cobalamin and iron deficiency may develop. In this case, the typical laboratory picture of B12 deficiency is masked, the diagnosis is missed, and treatment is delayed.
Diagnostic stages: screening and confirmation
Diagnostics of iron-deficiency states is based on a two-step scheme.
1. Screening (detection of IDA or latent iron deficiency):
- complete blood count (CBC);
- hematocrit;
- erythrocytes and reticulocytes;
- erythrocyte indices — MCH (mean corpuscular hemoglobin), MCHC (mean corpuscular hemoglobin concentration), MCV (mean corpuscular volume).
2. Diagnosis confirmation (serum iron metabolism parameters):
- ferritin;
- transferrin;
- TIBC;
- serum iron;
- TSAT.
Key serum parameters
| Parameter | What it reflects |
|---|---|
| Ferritin | tissue iron stores (depot) |
| Transferrin | iron-transport protein in blood |
| TIBC | total iron-binding capacity of serum |
| Serum iron | current circulating iron level |
| TSAT | fraction of transferrin bound with iron |
These parameters are used in combination with a comprehensive metabolic panel (blood chemistry), which also evaluates protein, pigment, and carbohydrate metabolism, enzymes (AST, ALT, ALP, GGT, LDH), and renal function (creatinine, urea).
Differential diagnosis and prevention
In the differential diagnosis of anemia (e.g., in patients with Crohn's disease), several parameters are evaluated simultaneously: folic acid, vitamin B12, serum iron, TIBC, and ferritin — Clinical Guideline Recommendation Level B, Level of Evidence 3.
Secondary prevention of iron-deficiency states is recommended at every medical visit, during routine check-ups and health screenings — this allows the detection of latent deficiency before overt anemia develops.
It is easy to remember the set of "serum" iron parameters: F-T-T-S-T — Ferritin, Transferrin, TIBC, Serum iron, TSAT. All five are always ordered together during the diagnosis confirmation stage.
Class and exam questions
Why is iron also tested when vitamin B12-deficiency anemia is suspected?
To rule out a combined cobalamin and iron deficiency, which masks the typical picture of B12 deficiency and hinders timely diagnosis.
How does screening differ from confirmatory tests?
Screening (CBC, hematocrit, erythrocyte indices) detects suspected iron deficiency, while serum parameters (ferritin, transferrin, TIBC, TSAT) confirm the diagnosis.
Which iron parameters are elevated in classical vitamin B12-deficiency anemia?
Serum iron and ferritin are generally elevated.
When is secondary prevention of iron deficiency recommended?
At every medical visit, during routine check-ups, and during health screenings.
What else to study on this topic
- Pathogenesis and stages of development of iron deficiency anemia
- Interpretation of UIBC (unsaturated iron-binding capacity)
- Features of iron metabolism in malabsorption syndrome
- Laboratory profile of anemia in Crohn's disease
- Erythrocyte indices MCH, MCHC, MCV in the differential diagnosis of anemias
- Blood biochemistry as part of a general therapeutic evaluation
Master the entire topic in the "Biochemistry" course
This is a summary. The course covers everything tested in classes and exams.
- Full study guide on "Laboratory Diagnostics of Iron Metabolism" and 3,616 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 115 video lessons on the subject
Free video lessons: biochemistryShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.