DEAR DR. ROACH: I am a 65-year-old woman who was recently diagnosed with iron deficiency and sent to a hematologist for two sessions of iron infusion. After completing this procedure, I found out from a home genetics testing company that I have two of the genes for hemochromatosis. My doctor ordered a clinical genetics test to make sure, and he found that I do have both genes: I am heterozygous positive for both the C282Y and H63D mutations. My doctor did an MRI scan to look for iron in the liver, and mine was normal.
I am confused and need to understand what to do in the future were I to be found to have iron deficiency and need infusions. I was told that I must have a leak, but tests have not indicated where or what is causing this iron deficiency. For now, my blood tests are normal and all my iron levels are normal as well. My health is excellent and I do not take any medications except for vitamins. -- D.C.C.
ANSWER: Normally, the body is able to regulate the amount of dietary iron absorbed. If you don't need much, your body won't absorb much. Hereditary hemochromatosis is a condition where iron absorption by the gut is set to maximal levels, no matter how much iron the body has. Over time, the iron builds up in the body and can damage the liver and heart, and may cause diabetes and joint damage. It is most prevalent in people of northern European ancestry.
The most common genetic variation causing symptomatic disease is called the C282Y -- at position 282 in the HFE gene, cysteine(C) is replaced by tyrosine(Y). When people have two copies of that mutation (genetically referred to as homozygous), hemochromatosis is much more likely to develop than in people without either copy of that mutation; however, not all of them will develop the hemochromatosis -- most estimates suggest that less than half of people will do so. Iron overload is more readily found in men than in women, as women have some iron loss through menstruation.
A second gene mutation, H63D, accounts for 2-5% of people with hemochromatosis. The likelihood of developing iron overload in your situation, with one C282Y mutation and one H63D mutation (called a compound heterozygote) is low: Probably less than 2% will develop iron overload. It is the iron overload, not the presence of the gene, that causes disease.
Your doctor looked for iron overload in you by MRI, which is nearly as good as the liver biopsy we used to do. You have no iron overload. In fact, you have iron deficiency.
It appears to me that the genetic information turns out to have nothing to do with your issue, but you may need further evaluation as to why you had iron deficiency.
DEAR DR. ROACH: You had a recent column on osteoporosis, and one thing I've never seen addressed is how sodium affects your bones' absorption of calcium. I was warned to drastically reduce my dietary sodium and I've always heard that salt was bad for you, but it's usually in relation to blood pressure. I have very good blood pressure. -- K.W.
ANSWER: High dietary sodium can indeed worsen osteoporosis. The mechanism seems to be primarily at the level of the kidney. With a high sodium diet, the kidney excretes extra calcium, along with potassium and phosphate. People with or at risk for osteoporosis should avoid excess sodium intake and get adequate calcium intake through dairy, some green vegetables (collard greens, broccoli rabe), and fortified juices.