A 92-year-old woman, a long-term patient still plying her trade as a piano teacher, came to me for a preoperative examination. She was experiencing shoulder pain that interfered with her piano playing, and she’d opted to undergo surgery. To our surprise, her preoperative blood work showed that she had a moderate anemia—a decrease in the number of red blood cells, whose mission it is to supply the rest of the body’s cells with oxygen.

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Although anemia can cause nonspecific symptoms such as fatigue and light­headed­ness, it has few overt physical signs, and the condition is often missed, especially in older adults.

Research shows that being anemic significantly worsens surgical outcomes, so the shoulder repair had to be postponed until the anemia was remedied. To do that, I needed to pinpoint the cause.

The most likely suspect was internal bleeding, possibly caused by the ibuprofen she’d been taking for shoulder pain. But an upper endoscopy (passage of a flexible, lit tube into the stomach) revealed no bleeding source. A colonoscopy also showed nothing. Perplexed, I referred her to a hematologist, a blood specialist.

Anemia is not a disease but a sign of one—and possibly a serious one—so finding the reason for it is important. And anemia, particularly mild anemia, is common as we age. A report in the journal American Family Physician notes that more than 10 percent of people older than 65 have some degree of anemia.

When Low Iron Is the Issue

There are many possible causes, but the most common is iron deficiency due to loss of blood. Blood-loss anemia occurs in about 9 to 14 percent of premenopausal women, a result of excessive menstrual bleeding. But in men and postmenopausal women that type of anemia is almost always due to gastrointestinal bleeding. Such bleeding is often caused by the widespread use of aspirin (yes, even baby aspirin) and nonsteroidal pain relievers such as ibuprofen (Advil, Motrin IB, and generic) and naproxen (Aleve and generic).

Other reasons for gastrointestinal bleeding include ulcers, polyps, hemorrhoids, and even cancer. Iron deficits can also accrue in the absence of bleeding, from an iron-poor diet or from poor absorption of dietary iron, as in severe celiac disease or colitis.

Sorting Out Other Causes

A deficiency of vitamin B12, which is required for the proper production of red blood cells in the bone marrow, is another frequent cause of anemia. The ability to absorb B12 is compromised in up to 1 of 3 people older than 60, possibly because of a decrease in stomach-acid production with age.

It is also impaired in people with pernicious anemia or inflammatory bowel disorders such as Crohn’s disease, and in those who regularly use the diabetes drug metformin (Glucophage and generic) and heartburn medications such as esomeprazole (Nexium and generic), lansoprazole (Prevacid and generic), and omeprazole (Prilosec and generic).

There are still more possibilities: Chronic kidney disease and chronic infection lead to insufficient production of red blood cells. Cancer cells can invade the marrow and crowd out blood-forming cells. Certain drugs can cause red blood cells to become coated with an antibody. That can lead to the cells dying far short of their normal three-month life span.

If you often experience fatigue and lightheadedness, check in with your doctor, especially if you regularly take over-the-counter pain relievers such as aspirin, ibuprofen, and naproxen. And note that black, tarry stools might be an indication of internal bleeding. If a simple blood test indicates anemia, a cause must be sought because treatment has to target the specific causative agent.

A Mystery Solved

So, what of my piano-teacher patient? The hematologist told me the cause of her anemia was cancer, a low-grade lymphoma. After a few treatments with an antibody-type drug regimen and two blood transfusions, she underwent a surgical repair of her torn shoulder tendon and was eventually back teaching future piano virtuosos.