Receptor Activator of Nuclear Factor κ-Β Ligand/Osteoprotegerin Axis in Adults with Hb S/β-Thalassemia and β-Thalassemia Trait

Abstract

There is not enough data about osteoporosis and the role of receptor activator of nuclear factor κ-Β ligand (RANKL)/serum osteoprotegerin (OPG) system in patients with double heterozygosity for sickle cell disease and β-thalassemia [Hb S (HBB: c.20A>T)/β-thal] and β-thal trait. Aim of the study was to investigate bone mineral densities (BMD) and the role of RANKL/OPG system in these cases. We studied 58 adults with Hb S/β-thal, 52 adults with β-thal trait, 34 healthy subjects as a control group. The BMD was determined by dual-energy X-ray absorptiometry (DEXA). Biochemical markers of bone metabolism (serum calcium, phosphorus, alkaline phosphatase, osteocalcin) parameters that affect bone metabolism (serum parathyroid hormone, thyroid-stimulating hormone, 25-hydroxyvitamin D, OPG, soluble RANKL [sRANKL]) were studied. Femoral neck Z-scores of 93.2% for β-thal trait, 83.0% for Hb S/β-thal patients were within the expected range. Lumbar spine Z-scores of 89.1% for β-thal, 90.2% for Hb S/β-thal patients were above −2.0 SD. Z-scores of the control group were within the expected range. Median serum sRANKL level was 2.80, 4.52, 5.79 pmol/L in Hb S/β-thal, β-thal trait, control groups, respectively (p = 0.010). Median serum OPG level was 1.07, 0.86, 0.86 pmol/L in Hb S/β-thal, β-thal trait, control groups, respectively (p < 0.001). β-Thalassemia trait alone is not a risk factor for osteopenia/osteoporosis and osteoporosis does not develop in premenopausal women and men younger than 50 years with Hb S/β-thal. However, as we determined lower levels of osteocalcin, compensatory decrease of sRANKL with compensatory increase of OPG, more severe osteoporosis may develop in advanced ages in these patient populations.

Keywords:

• Bone mineral density (BMD)
• osteoporosis
• osteoprotegerin (OPG)
• receptor activator of nuclear factor κ-Β ligand (RANKL)
• sickle cell disease
• thalassemia

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

This study was supported by the Mersin University Scientific Research Projects [BAP-TF DTB (AT) 2010-3 code].