The hematologist obtained several other lab results and called me. The boy would need a blood transfusion and would have to be hospitalized for a day or two. The specialist added several more tests, including one to measure how fast red blood cells called reticulocytes are made by the bone marrow and released into the blood. Reticulocytes are in the blood for about two days before developing into mature red blood cells.

The more anemic you are, the higher your reticulocyte count should be. Yet this child's was less then 1 percent, when we would have expected it to be more than 5 percent.

Why wasn't his bone marrow doing its job?

TEC, or transient erythroblastopenia of childhood, was first described in 1970. It is one of the most common causes of decreased red blood cell production in young children. It's usually detected through routine screening, as with our patient, or when a parent notices a child seems tired and pale.

Why it occurs is still unknown, but there is usually a viral infection before children develop TEC. The anemia typically resolves in a month or two and usually does not recur.

After one transfusion of red blood cells, my little patient recovered nicely. On his last repeat blood test, he had a robust hemoglobin of 12 and was bouncing happily around the exam room, his rosy cheeks signaling his complete recovery.