Photo Credit: Oleksandr Hruts

“If hemoglobin is low, especially if they are all in the anemic range, fracture risk should be considered,” says Mattias Lorentzon, MD, PhD.

Decreasing hemoglobin (Hb) levels and anemia have been associated with increased risk for osteoporotic fracture. However, the added benefit of the Fracture Risk Assessment Tool (FRAX), the most common fracture prediction tool worldwide, is unknown, according to Mattias Lorentzon, MD, PhD.

For a study published in The Journal of Clinical Endocrinology & Metabolism, Dr. Lorentzon and colleagues analyzed the association between anemia, Hb levels, bone microstructure, and risk for incident fracture and to assess whether Hb levels improve fracture risk prediction in addition to FRAX clinical risk factors.

Fractures Often Lead to Loss of Physical Function

“Fractures in older women often lead to loss of physical function, increased morbidity, and mortality as well as decreased QOL,” says Dr. Lorentzon. “Thus, it is important to identify women at risk so that these fractures can be prevented. In our study, we demonstrate that using hemoglobin levels can improve fracture risk prediction.”

The study aimed to not only determine if hemoglobin levels improve fracture risk prediction but also by which mechanisms this occurs, Dr. Lorentzon explains. The prospective population-based cohort study included 2,778 community-dwelling women aged 75 to 80. At baseline, the study team gathered information on common fracture predictions, anthropometrics, and falls. The study team took blood samples and evaluated skeletal characteristics using high-resolution peripheral quantitative CT and dual-energy X-ray absorptiometry. At follow-up, incident fractures were accessed from an X-ray archive.

Women With Anemia & Low Hb Have Higher Risk for Fracture

“We found that women with anemia and low Hb levels had higher risk for fracture and that low Hb was associated with lower cortical bone mineral density, which may contribute to increased fracture risk.” He adds that having low Hb and anemia particularly increases fracture risk in older women and that Hb should be considered in addition to risk factors normally assessed using the FRAX risk calculator.

“It is clear that Hb levels are associated with fracture risk and with mortality,” he says. “For fracture, the relationship is apparently linear, meaning higher Hb is linked with lower risk. For mortality, Hb levels above 13 g/dl are not associated with a mortality benefit (ie, no clear linear relationship; Figure).

Few Resources Are Needed to Measure Hemoglobin Levels

Most patients have their Hb levels measured in their routine laboratory tests, Dr. Lorentzon notes. “Few resources are needed to measure patients’ Hb concentration as it is typically part of standard clinical assessment,” Dr. Lorentzon says. In addition, many of the patients being evaluated for fracture risk already have a recent Hb result available.” Therefore, he adds, integrating Hb levels into fracture risk prediction is practical from a resource point of view.”

“If Hb is low, especially if they are all in the anemic range, fracture risk should be considered,” he says. “This information contributes to the other clinical risk factors in FRAX.”

Anemia and decreasing levels of Hb are linked with lower BMD, worse cortical bone traits, and incident fracture, independently of FRAX clinical risk factors and bone mineral density in older women. Considering Hb levels may improve the clinical evaluation of patients with osteoporosis and the assessment of fracture risk.

For future research, Dr. Lorentzon and colleagues agree that it would be best to investigate if the increased risk in those with low Hb can be reversed when the anemia is treated.