Health & Medicine / Nutrition

The lowest hemoglobin I'd ever seen in a child was 3.6 in a 3-year-old girl with pneumonia. She had stopped breathing right in front of me. The lung infection had overwhelmed her body's ability to make up for the anemia that compromised her oxygen supply. Luckily, we were able to treat her, and she did fine.

I told the boy's father that his son needed hospital care. I also explained that severe anemia had sapped his energy to walk and talk.

When I saw the child's full lab report, I was relieved to see that his white blood cells and platelets were at normal levels. No leukemia. The analysis also noted, however, that his red blood cells were small, lacking in color, and in some cases unusually shaped. Problems in red blood cell formation can occur because of genetic diseases or more often because of a lack of iron in the diet. Red blood cells are packed with hemoglobin, and each hemoglobin molecule requires four oxygen-binding iron atoms. In the absence of sufficient iron, red blood cells cannot form properly.

The pieces came together when the father told me the boy had been consuming almost nothing but milk for many months. Cow's-milk protein can cause a low-grade inflammation in the intestinal lining. Although the irritation is not enough to trigger pain or vomiting, it does cause microscopic bleeding. If the blood loss goes on long enough and the child is not consuming any iron-containing foods or supplements, profound anemia is inevitable. Children under the age of 3 are particularly vulnerable because the protective intestinal lining hasn't fully matured.

Doctors routinely tell parents not to give whole cow's milk to infants until their first birthday and instruct parents at the 1-year-old well-child visit to make sure their child is taking in a variety of foods, not just milk. For some reason, this baby's parents hadn't gotten the message. Perhaps his severe asthma had preoccupied both his doctors and his parents. Fortunately, he quickly responded to a blood transfusion. The following day he was much more active and alert. Before he went home with his parents, they were counseled about diet and given iron supplements to build up the boy's iron stores over the next two to three months. After that, he would take regular vitamins with iron.

Many parents worry when a toddler doesn't like milk. I tell them about other sources of calcium like soy milk or calcium supplements. And I tell them about the babies who become anemic from drinking nothing but milk: "Cow's milk is not an essential nutrient, unless you're a calf!"

Mark Cohen is a pediatrician in Santa Clara, Califoria. The cases described in Vital Signs are real but the authors haave changed some details about the patients to protect their privacy.

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