Еще некоторые размышления по поводу диагностики железодефицита:
It is well established that in healthy people, the overwhelming majority of those seeking help for hair loss, serum ferritin provides the most reliable estimate of iron deficiency in the absence of bone-marrow iron-staining data1 but what parameter should the clinician use in patients with hair loss? To address this issue we need to inquire how laboratory reference ranges for serum ferritin and hemoglobin (Hb) were derived.
In 2001, Rushton et al questioned the use of a lower reference limit for Hb, red blood cell count, and serum ferritin in menstruating women, and suggested that these anomalies were a result of sampling populations considered normal but containing a large proportion of female patients who were iron deficient. This hypothesis was supported by a large-scale US study that showed 39% of women had a serum ferritin level below the lowest male value, whereas 38% of women were iron deficient using a transferrin saturation level of below 20%, a recognized indicator of deficiency.
Bone-marrow iron staining correlates with serum ferritin concentration in individuals with an erythrocyte sedimentation rate of less than 10 mm/h. These studies show a wide range of serum ferritin values corresponding with an absence of iron staining in bone marrow. Guyatt et al4 found a serum ferritin concentration of 50 μg/L was associated with a 50% chance of an absence of iron in bone marrow. From the data of Puolakka5 the calculated 99% confidence limit for bone-marrow iron staining is a serum ferritin greater than 70 μg/L.
Clearly, using the current lower reference limits derived from populations containing a large proportion of iron-deficient individuals leaves the clinician believing their patient is iron replete. This quandary affects the entry and completion points in designing clinical trials investigating iron deficiency and hair loss. For example, one group used their laboratory's parameter for serum ferritin of less than 20 μg/L to define iron deficiency in 5 patients with unexplained chronic telogen effluvium. They then claimed that because these 5 patients had a serum ferritin level above this limit (>20 μg/L) there was no association between iron and unexplained hair shedding. We would question their conclusion.
To our knowledge, there is no published evidence supporting a lower biological need for serum ferritin or Hb in menstruating women compared with their male counterparts, neither is there evidence for lower Hb concentration in any other mammal including the menstruating Old World primates. No other mammal shows a sexual dimorphism in Hb or iron status; why should human beings be the exception? Consequently, we would suggest using a serum ferritin greater than 70 μg/L when considering whether or not to instigate iron therapy in unexplained chronic telogen effluvium.
Из Iron and hair loss in women; what is deficiency? This is the real question!
J Am Acad Dermatol. 2007 Mar;56(3):518-9
Фрагмент ответа на этот комментарий:
Many laboratories use serum ferritin concentrations of 10 to 15 ng/mL as the lower limits of normal. This yields only a sensitivity of 59% and a specificity of 99% for diagnosing iron deficiency. Using a cutoff of 41 ng/mL yields a sensitivity of 98% and a specificity of 98% for diagnosing iron deficiency. Dr Rushton and colleagues cite a study that showed that the calculated 99% confidence limit for bone-marrow iron staining is a serum ferritin level greater than 70 ng/mL. Our own anecdotal experience is that treatment for many forms of hair loss is enhanced when patients maintain a serum ferritin concentration greater than 70 ng/mL.
In our clinic, when a patient does not have anemia (ie, the patient has a normal hemoglobin and hematocrit level) but has a serum ferritin concentration less than 70 ng/mL, we call this condition ‘‘nonanemic iron deficiency.’’
J Am Acad Dermatol. 2007 Mar;56(3): 519
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