Hemoglobin incorporation method

In the hemoglobin incorporation method, absorption is estimated from the amoiint of tracer appearing in the blood. The principle of this method is based on the observation that absorbed iron is incorporated into circulating hemoglobin 10 to H days after dosing (7). A factor of 75% to 90% is usually introduced to correct for the incomplete utilization of absorbed iron for hemoglobin synthesis in normal subjects (8). 

The aim of this study was to further explore the potential and limitations of using stable iron isotopes as tracers and EI-MS in absorption studies. Procedures were developed for preparing iron acetylacetonate from both blood and fecal samples for mass spectrometric analysis. The precision and accuracy of ion abundance measurements were evaluated. In vivo use of stable iron isotope tracers was tested with a human study in which 54pe and 57pe were given orally and absorption was estimated with the fecal monitoring and hemoglobin incorporation methods. 

Hemoglobin incorporation method 6.73 mg 54Fe in orange juice... 

The Hemoglobin Incorporation Method. The hemoglobin concentration of each blood sample was determined, and iron chelates were prepared for abundance measurements. The blood volume was estimated from the equation of Jarnum (24>) t... 

Errors associated with iron quantification and abimdance measurements are common to both fecal monitoring and hemoglobin incorporation methods According to Janghorbani and Young (2 )> acceptable absorption estimates can be obtained if the precision of these measurements is kept below 5% The analytical procedures developed in this study are thus considered satisfactory since the relative standard deviation was 2 48% for total iron quantification and less than 2% for ion abimdance determinations ... 

In the hemoglobin incorporation method, estimation of blood volume from height and weight may introduce a 5% error (29) A... 

Comparison of Absorption Data. Little correlation was found between the absorption data obtained with the hemoglobin incorporation and fecal monitoring methods with or without correction for PEG recovery (Table VII). There are several possible reasons for this poor correlation. 

This inconvenience is obviated by administering two different iron isotopes to the same individual and —one by injection, the other administered orally. The amount of iron used to form hemoglobin can be accurately determined by following the appearance and disappearance of the injected isotope. When rates of incorporation into the blood of the injected and the ingested isotope are compared, the proportion of absorbed iron can be estimated accurately. This method is valid only if the distribution of injected and ingested iron is the same throughout the body. Whether this assumption is correct, especially under pathological conditions, remains to be established. 

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