My ferritin is 28 — is that low?
Swiss sports doctors call under 15 µg/L empty and 15-30 low stores, with 30 their adult cut-off (50 before elite altitude camps); expert-set lines, read with CRP and by a clinician.
Main caveat: No method. No search, grading or consensus process is reported; the cut-offs are the authors' synthesis of reviews.
The Swiss Society of Sports Medicine set out how its physicians should diagnose and treat iron deficiency in athletes while avoiding iron overload, against a Swiss "iron hype" and an earlier finding that top Swiss athletes took supplements uncritically.
The first-line tests are haemoglobin, haematocrit, MCV, MCH and ferritin; because ferritin is an acute-phase protein, an inflammatory reaction (training sessions, infections) must be excluded by history and CRP, and in unclear cases the tests are repeated or zinc protoporphyrin, soluble transferrin receptor and transferrin saturation are added.
Ferritin under 15 µg/L is "very specific" for empty stores and 15-30 µg/L means low stores, so the authors take 30 µg/L as a reasonable cut-off for adults and adolescents from 15 years, 20 µg/L at 12-15 years and 15 µg/L at 6-12; before altitude training in adult elite sport, ferritin should reach 50 µg/L.
Anaemia is haemoglobin below 140 g/L in men and 120 g/L in women — but in about 10-15% of mainly endurance athletes, especially above 10 hours of training a week, a low haemoglobin with normal ferritin, MCV and MCH is dilutional pseudoanaemia from plasma volume expansion, which does not impair performance.
Treatment is dietary counselling plus usually 40-60 mg of elemental iron once a day; IV iron is for oral failure, the need for immediate restoration, intolerance, concomitant disease (e.g. depression) or low stores before an altitude camp, given only where resuscitation skills are available, with 30 minutes of observation and respect for WADA's infusion rule.
Blood tests are repeated 6-8 weeks after starting treatment, and long-term iron with normal or high ferritin "is not recommended and may be harmful".
Our reading: this is the base's only sports-medicine source with explicit, age-specific ferritin cut-offs and an altitude target; it is a clinician's statement whose numbers are expert-set, and it is older and more confident about performance ("all types of iron deficiency may affect physical performance") than the later trials.
Protocol
Design: consensus statement; n = not applicable. No methods section: no search, no inclusion criteria, no grading, no voting is reported.
Scope: definition and stages of iron deficiency (non-anaemic iron deficiency NAID; iron deficiency with microcytosis and/or hypochromia IDMH; iron-deficiency anaemia IDA), laboratory tests and their limits (Table 1), dilutional pseudoanaemia, excessive haematocrits and doping controls, performance (Table 2: ten randomised blinded trials of NAID and performance), nutrition, oral and IV iron, monitoring, overload, children and adolescents (Table 3).
Funding and interests: "No financial support and no other potential conflict of interest relevant to this article was reported."
Key Results
| Topic | What the statement says |
|---|---|
| First-line tests | Haemoglobin, haematocrit, erythrocytes, MCV, MCH, ferritin; history and CRP (normal <3 mg/L) to exclude acute-phase reactions; if unclear, repeat or add zinc protoporphyrin, soluble transferrin receptor, transferrin saturation |
| Anaemia | Haemoglobin normal above 140 g/L in men and above 120 g/L in women |
| Ferritin cut-offs | <15 µg/L empty stores; 15-30 low stores; 30 = cut-off for adults and from 15 years; 20 at 12-15 years; 15 at 6-12 years; 50 before altitude training in adult elite sport |
| Transferrin saturation | 20% and below defines iron deficiency, but inflammation can give 10-20% without iron deficiency |
| Exercise and ferritin | After exercise ferritin may stay normal, rise 27% and return to baseline within a day or, after ultramarathons, double and return only after 6 days |
| Dilutional pseudoanaemia | In about 10-15% of mainly endurance athletes, especially above 10 hours a week: low haemoglobin and haematocrit, normal red-cell mass, ferritin, MCV and MCH; serial blood counts, and haemoglobin mass (CO rebreathing) if still unclear |
| Losses | Main exercise loss: gut micro-ischaemia; sweat and urinary losses "not relevant" in absolute terms; foot-strike haemolysis exists but loses no iron; plus hepcidin "bursts" blocking absorption |
| Diet | Meat, poultry or fish at least 5 times a week; vitamin C, meat peptides and fermented food enhance, phytates, oxalates, polyphenols (tea, coffee) and calcium inhibit; iron-deficiency anaemia "cannot be corrected by nutrition alone" |
| Oral iron | 40-60 mg of elemental iron once daily; side effects (nausea, dyspepsia, constipation, diarrhoea) usually not serious |
| Maintenance | Repeatedly low stores: 14-28 mg a day or 40-60 mg two to three times a week (the conclusions say two tablets a week); vegetarian athletes, to prevent deficiency and in place of meat, with no test as the condition: 40-60 mg three times a week or at least 14-28 mg a day |
| IV iron | For oral failure or immediate restoration; non-responders, intolerance, concomitant disease (e.g. depression), low stores before an altitude camp; resuscitation skills and 30 minutes of observation; WADA rule as quoted in 2015 (not checked against the current list): infusions or injections of more than 50 mL per 6 hours prohibited except those received in hospital admissions or clinical investigations; transient hypophosphataemia frequent after ferric carboxymaltose |
| Monitoring | Repeat the basic tests 6-8 weeks after starting diet, oral or IV iron; twice a year (summary) or two to three times a year in high-level endurance athletes (conclusions) |
| Adolescents | Same first step (diet, often with oral iron); for IDMH or IDA 5 mg/kg/day for 3 months in two or three doses; re-test after 6-8 weeks |
| Without deficiency | Long-term daily oral or IV iron with normal or high ferritin "is not recommended and may be harmful"; no excretion pathway; oxidative stress and colorectal-cancer data cited as reasons for care |
Performance (Table 2 and text): the authors read the trials as showing that all stages of iron deficiency impair performance, citing improvements in non-anaemic iron-depleted endurance athletes, while noting that in Garvican 2014 haemoglobin mass, VO2max and run time to exhaustion rose only in the clearly deficient group given IV iron (ferritin <15, or <35 with transferrin saturation <20%), not in those with ferritin <65.
Why 30: WHO uses 15 µg/L, bone-marrow studies 16-32 µg/L; considering fatigue as well as erythropoiesis "the cut-off may be slightly higher"; a cut-off of 50 µg/L from fatigue trials "must be interpreted with caution because of methodological concerns"; "a ferritin cut-off of 30 mcg/l in adults seems to be most plausible".
Mechanisms
Measured (in the studies cited): exercise raises hepcidin, which blocks absorption and the transfer of iron from macrophages to red-cell precursors; ferritin rises as an acute-phase protein after hard or long exercise; plasma volume expands with years of endurance training.
Authors' interpretation: the main exercise-related losses are gut micro-ischaemia and hepcidin bursts; haemoglobin mass, not concentration, tracks endurance capacity, so a low haematocrit with a large plasma volume is "by no means a disadvantage".
Authors' interpretation: because there is no route to excrete iron, supplementation must always be careful.
Inference: the exercise-ferritin figures (a 27% rise gone within a day; after ultras, double the pre-race value and back to baseline only after 6 days) say the confound is session-dependent — large after very long races, small after ordinary training — which REF-1414 measures for a marathon and a 130-km ultra.
Practical Application
My ferritin is 28 — is that low? Swiss sports doctors call under 15 µg/L empty and 15-30 low stores, with 30 their adult cut-off (50 before elite altitude camps); expert-set lines, read with CRP and by a clinician.
Read a ferritin as a range with a purpose: these are athlete cut-offs for a clinical decision; WHO's 15 is cited here without its purpose, the BSG's 15/30/45/150 serve the decision to investigate anaemia (REF-1411), 35/20 is sport-science staging (REF-1409), Pengelly's <40 is a review's inclusion line (REF-1420), and >200 is Mettler's overload definition in amateur runners (REF-1419). None is a law.
When to draw blood: not straight after hard training or during an infection; CRP alongside (consensus). After an ultra, ferritin doubled and took 6 days to return to baseline in the studies cited; REF-1414 found it raised for up to 5 days after a marathon or ultra.
Altitude — the sources disagree, for the [SYNTH-06] owner: this statement aims for ferritin 50 µg/L before altitude in adult elite athletes and lists low stores before a camp among the reasons a physician may consider IV iron; the base's own practice in SYNTH-06 is "≥ 40-50 ng/mL" and, when ferritin is low, "the camp waits". The 50 here is an elite-adult target, not a general one.
Vitamin C: this statement advises enhancers (vitamin C, e.g. orange juice instead of tea or coffee with an iron-containing meal), while the BSG guideline (REF-1411) does not recommend vitamin C with an iron tablet; the BSG names only tea (its effect "dissipates within 60 min") and advises taking the tablet fasting or between meals; coffee and calcium are this statement's, not the BSG's.
Low haemoglobin in a high-volume athlete: may be dilution, with normal ferritin, MCV and MCH; whether it is anaemia is the clinician's reading, not the assistant's.
IV iron is a physician's decision in a setting with resuscitation skills and under anti-doping rules; not from this paper, the base's own practice: the assistant does not suggest it.
Adolescents and vegetarians: the age cut-offs (15, 20, 30) give SYNTH-81 its first sourced numbers; for vegetarian athletes the statement recommends preventive intermittent iron without a test as the condition, expert opinion that SYNTH-97 states as a disagreement with its test-first default (consensus, not trials).
Limitations
No method. No search, grading or consensus process is reported; the cut-offs are the authors' synthesis of reviews.
Not outcome-validated thresholds. No prospective study links 30 (or 50 before altitude) to performance or health outcomes in athletes.
Internal inconsistencies. Re-testing is "twice a year" in the summary and "two to three times a year" in the conclusions; maintenance is "two to three times per week" in the text and "two iron tablets per week" in the conclusions; one maintenance dose is printed "14 to 28 m".
Swiss and dated specifics. IV products available in Switzerland in 2015; the WADA wording quoted (50 mL per 6 hours) was not checked against the current Prohibited List.
The saved text comes from the publisher's HTML; table cells are flattened and some rows of Table 3 appear out of place.
Funding and interests: none reported, as printed.
How this entry was checked and changed
Why this level
a national sports-medicine society's consensus statement (the rubric's consensus / position statement is A), held at A- because the paper describes no systematic search, no grading of evidence and no consensus process, and its ferritin cut-offs are the authors' choice from reviews ("seems to be most plausible"). Read from the full text (the publisher's open-access HTML, CC BY-NC-SA 4.0)
Full text (checked 2026-10-28)
In healthy male and female athletes >15 years, ferritin values <15 mcg are equivalent to empty, values from 15 to 30 mcg/l to low iron stores; therefore a cut-off of 30 mcg/l is appropriate (full text)
For children aged from 6–12 years and younger adolescents from 12–15 years, cut-offs of 15 and 20 mcg/l are recommended; a ferritin value of 50 mcg/l should be attained in athletes prior to altitude training (full text)
Based on the cited results and several review articles, a ferritin cut-off of 30 mcg/l in adults seems to be most plausible (full text)
Hb cut-off: Women: >120 g/l, Men: >140 g/l; CRP <3 mg/l; transferrin saturation may be between 10 and 20% without iron deficiency in inflammation (full text)
Ferritin may stay normal, show a rise of 27% with a return to baseline within a day or, in ultramarathons, be double as high as the prerace value and return to baseline only after 6 days (full text)
Dilutional pseudoanaemia in about 10–15% of mainly endurance athletes, especially when training time exceeds 10 hours per week (full text)
We therefore recommend supplementation of 40 to 60 mg of elemental iron once daily; repeat the basic blood tests 6 to 8 weeks after the start of therapy (full text)
Intermittent substitution: 14 to 28 m elemental iron per day or 40–60 mg elemental iron two to three times per week (full text)
i.v. iron only where resuscitation skills are available and observation of the patient for 30 minutes can be guaranteed; WADA: infusions of more than 50 ml per 6 hour period are prohibited (full text)
Long-term daily oral iron intake or i.v. supplementation in the presence of normal or even high ferritin values is not recommended and may be harmful (full text)
No financial support and no other potential conflict of interest relevant to this article was reported (full text)