Medical Mystery | What caused a teen’s unexpected weight loss?

Though she had been suffering with bloody diarrhea for months, a 16-year-old girl was too embarrassed to tell her father about it. But as her abdominal cramps got worse, she finally confided in him, and he brought her to the emergency department.

What’s more, she had lost 20 pounds in the last year without intending to — and as a high school wrestler, she had the weight logs to document it.

In the ED, her vital signs and blood oxygen level were normal. But she was extremely pale, and her abdomen was tender. An intravenous line was placed to draw blood and give her fluids and medications.

While awaiting results, the doctor spoke with the patient alone. The doctor was concerned that the weight loss may have been intentional so that she could wrestle in a lower weight class. However, she said she would be happy wrestling at a higher weight. She did not restrict her intake, count calories, weigh herself, purge, or display any other symptoms of an eating disorder. She said she recently skipped a menstrual period, but pregnancy was ruled out as she hadn’t had sex. Substance abuse can cause weight loss and fatigue, but when asked about this, she replied: “Of course not, I’m an athlete!”

The doctor soon received a call from the lab with a critical finding — her hemoglobin was only 4.4 g/dL (normal range 12-16 g/dL). Hemoglobin is the protein in red blood cells that carries oxygen through the body. So when a patient is anemic, symptoms can include fatigue, shortness of breath, and weakness. There are many different causes of anemia, and they can be acute or chronic. Since she had symptoms for months, her anemia was considered chronic. This was fortunate as it meant that her body had time to adjust to the low hemoglobin level, accounting for the fact that she could still wrestle.

Although the bloody stools appeared to be the cause of the anemia, the doctor wanted to rule out other causes. Heavy or prolonged menstrual bleeding is one of the most common causes of anemia in teenagers. Her bleeding was normal — usually monthly, lasted 5 days, and required about 3 menstrual pads a day. Her skipped menstrual period could have been due to the weight loss. She did not have nose bleeds or excessive bruising, making a bleeding disorder unlikely, and she said she had neither fevers nor night sweats, making cancer also unlikely.

The doctor concluded that the bloody stools were, in fact, the culprit. The patient was admitted to the hospital where she received two blood transfusions as well as IV iron, as chronic blood loss depletes the body’s iron stores. Her blood tests, stool tests, and special GI (gastrointestinal) tract imaging (MRI enterography) indicated that she had severe GI inflammation. This confirmed that she had inflammatory bowel disease, either Crohn’s disease or ulcerative colitis (UC).

Both conditions are being diagnosed more frequently in teens and young adults than they were in the past. Their exact cause isn’t clear, but it is thought to be a combination of genetics, the immune system, and environmental factors, including Western diets high in processed foods.

The main difference between the conditions is the location of the inflammation. In Crohn’s disease, inflammation can occur anywhere in the digestive tract, from mouth to anus, with healthy areas interspersed with inflamed areas. In UC, inflammation is continuous throughout the colon and rectum. Her diagnosis is UC, and she will need to have specialized care from a GI doctor to manage the condition.

Ryan Cowan is a pediatric resident and Rima Himelstein is an adolescent medicine specialist at Nemours Children’s Health, Delaware.