Vertebral Bone Density Measurements by DXA are Influenced by Hepatic Iron Overload in Patients with Hemoglobinopathies.

Interference from metal hardware (piercings; buttons on clothing; and ingested material, e.g. barium) is well documented in bone health assessments by dual-energy X-ray absorptiometry (DXA). It is unknown if iron in hepatic tissue of highly iron-loaded patients could be mistakenly assessed by DXA as bone, and if this would lead to increased areal bone mineral density (aBMD) lumbar spine Z-scores derived by DXA. Our hypothesis is that iron in the liver of heavily loaded patients will artificially raise aBMD in the spine, and thereby lead to an error in the DXA scan. This study consisted of a retrospective chart review and re-analysis of DXA scans from patients with sickle cell disease and thalassemia combined with prospective DXA and liver iron concentration (LIC) measurements from healthy controls. Patients who previously had both a DXA and LIC measurement were compared with controls. aBMD of individual vertebrae were analyzed and grouped by those that may be covered by the liver (L1 or L1/2) with those typically not (L3/4). Subjects were grouped by diagnosis and LIC severity. Phantoms were created to mimic the geometry of iron loaded liver tissue, and analyzed by DXA. A significant effect was observed in the difference of BMD Z-score of L1 and L 3/4 when patients with LIC < 1000 were compared to those with >5000 µg Fe/g wet tissue (p = 0.043). A significant relationship was also observed in the difference in aBMD Z-score of L1 and 3/4 when controls were compared to the high iron group (p = 0.037). These findings were supported by phantom experiments. These results suggest that there is a relationship between hepatic iron and increased L1 aBMD Z-scores in highly iron-loaded patients. Given patients with hemoglobinopathies are at increased risk for osteoporosis, clinicians should maintain a higher index of suspicion when diagnosing low bone mass.

A simple model to assess and improve adherence to iron chelation therapy with deferoxamine in patients with thalassemia.

Adherence to deferoxamine (DFO) is vital for the long-term survival of patients with thalassemia; however, currently no measure exists to quantify adherence directly. In this study, 90 patients with thalassemia major underwent liver iron concentration (LIC) assessment by SQUID biosusceptometer, were asked to rate their adherence to DFO using a Numerical Likert Scale (NLS), and were educated about complications of iron overload. Of 38% (n = 28) of patients who rated themselves as very compliant, 19 had elevated LIC related to inadequate dosing of DFO and nine reported nonadherence in the past. Adherence improved after counseling and LIC decreased by 25% (7-60%) in eight previously noncompliant patients who returned for subsequent LIC over 15 months. In conclusion, the NLS seems to be a simple but reliable tool to assess patients' adherence to DFO. Education and frequent noninvasive LIC assessments can improve adherence and iron burden. Elevated LIC does not necessarily reflect concurrent noncompliance; however, it can be an indication of nonadherence in the past.