I scanned the patient's chart: "14-month-old boy with a cold, not eating." The child's father, a brown-skinned man in his forties, held his son in his lap. The baby was listless, his skin a pale yellowish-white. Jaundice was my first suspicion.
After introducing myself, I asked the father, "Does your son have any medical problems?"
He answered slowly, with the accent of his native Philippines: "My son has asthma."
Asthma does not cause jaundice. The boy's lips were pale, almost gray, with no pink color at all. His fingernails, too, were so pale they looked almost chalky. Normally, his skin color would have been much like his father's, a rich, light yellowish-brown, but all the red and pink tones had vanished. This baby was probably severely anemic, which meant he was low in oxygen-carrying red blood cells. But asthma doesn't give you anemia either.
The baby was breathing somewhat rapidly, and I heard a few wheezes, but I saw no sign of a breathing obstruction. The boy gazed at me, slumped in his father's lap, hardly moving.
When I checked the computer for his medical records, the most recent entry gave me a jolt. Four months ago, he was admitted to the hospital with the diagnosis "asthma with acute respiratory failure"—a serious and sometimes fatal condition. Fortunately, the boy had recovered fairly quickly.
I listened to his lungs again. Although they didn't sound bad, I called to the nurse: "Let's check his oxygen. Give him oxygen if he needs it, and let's also give him an albuterol breathing treatment."
I wasn't going to take a chance. Although the boy's asthma seemed mild, I would treat it aggressively, hoping to head off a severe episode. Still, I wondered, why was he so pale?
The only medication he was taking was for his asthma. The father added that the boy had been pale and lethargic for the last two or three months. He had not been eating—only drinking milk. He no longer babbled, and he had lost interest in crawling or walking.
Was some progressive disorder causing anemia and affecting his brain? Leukemia could do that, as could some other rare disorders. I examined the boy for signs of leukemia or another malignancy, like an enlarged spleen, swollen lymph nodes, or signs of bleeding in the skin. Fortunately, I saw no warning signs. I also checked to see if the anemia had progressed to the point that his blood no longer carried enough oxygen for his body's needs. His heart and lungs were working hard, but he didn't seem in immediate danger.
When I saw that he was stable, I sent him for tests to determine the level of hemoglobin—the oxygen-carrying molecule—in his blood. The results would show the severity of his anemia. Normally, a 14-month-old's hemoglobin is around 10 to 13. A few minutes later, the lab clerk called.
"Dr. Cohen, we have a critical value. The hemoglobin is 2.2."
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.