You indicate that you are a compound heterozygote for hemochromatosis.
Compound heterozygote: The presence of two different mutant alleles (that can cause genetic disease in a heterozygous state) at a particular gene locus, one on each chromosome of a pair.
Compound heterozygotes can be divided into two groups:
- subjects with iron overload (with elevated ferritin levels) or
- those without (with normal ferritin concentrations).
More than 80% genetic hemochromatosis patients are homozygous for this mutation (mutation C282Y). The heterozygous state for this mutation is highly prevalent in the general population
Compound heterozygotes for the C282Y and the H63D mutations may have a comparatively higher risk of iron overload or genetic hemochromatosis than single heterozygotes of the C282Y mutation. Liver biopsy and hepatic iron evaluation are also recommended in compound heterozygotes (C282Y/H63D) and C282Y heterozygotes, who have indirect markers of iron overload, particularly if they also have abnormal liver enzymes or clinical evidence of liver disease. These individuals account for a small proportion of phenotypic hemochromatosis and they have a relatively low likelihood of significant iron overload. Elevated values of iron tests in them are often due to other causes of liver disease including alcoholic liver disease.
Indirect markers of iron stores such as serum iron or ferritin lack specificity when used alone.
Transferrin Saturation (TS): Safe range - 12-44%. Any values above this range must be considered diagnostic for hemochromatosis. Any values far below this range may be a sign of chronic infection, bleeding ulcers, or cancer.
The amount of storage iron - Serum Ferritin (SF): Safe range - 5-150 µg/L. A hemochromatosis patient needs to be at the lowest end of this range. A value of <10.
needs to be the treatment goal.
Interpretation of these results at times may not be as straightforward as they appear.
African Americans in the U.S have a 20% carrier rate. This population has one special problem, and that is in that the main screening lab value - transferrin saturation (TS), sometimes seems normal. In this one group, one may need to depend on family history, symptoms or elevated serum ferritin as a diagnostic parameters to determine hemochromatosis.
Some studies indicate that the mean transferrin saturations within the middle and upper sub-populations for African American men and women were from 8% to 16 lower, whereas mean serum ferritin concentrations were substantially higher than those for Caucasians of the same gender.
Since serum iron can be elevated by eating and can fluctuate during the day, serum iron measurements should be done fasting, usually in the morning before breakfast. Measurement of transferrin saturation is ideally performed after an overnight fast. Overnight fasting avoids postprandial or circadian variations and eliminates nearly 80% of false-positive TS results. Simultaneous serum ferritin determination increases the predictive accuracy for diagnosis of iron overload.
As you can well appreciate, the values that you have provided must be interpreted in the context of
- the normal fluctuations of serum iron,
- overnight fasting prior to testing(yes/no) ,
- influence of ethnicity on some of the values, and
- presence or absence of associated liver disease/alcoholism.
MB BS, MS, FRCS(Edinburgh)