SENSORY NEURAL HEARING LOSS IN Β-Thalassemia MAJOR PATIENTS TREATED WITH DEFEROXAMINE

Abstract

This study evaluated the incidence of sensory neural hearing loss (SNHL) in beta-thalassemia major patients treated with deferoxamine in Mofid Children's Hospital. Based on the patients' file review, this descriptive and cross-sectional study was performed in all thalassemia patients older than 5 years old who were treated with regular blood transfusion and deferoxamine pump injection during the year 2006. The first visit with the otolaryngologist was performed in all patients to demarcate the presence of cerumen, otitis, and congenital abnormalities of ears. Then pure tone audiometery in frequency ranges of 250-8000 Hz was performed. Data statistical analysis was done by Mann-Whitney, chi square, and Fisher tests. There were 67 patients over 5 years old in our study. Five patients (7.4%), including 2 boys and 3 girls, in the age range of 7-24 years (mean:17.8 +/- 6.6 years) had SNHL. Their hearing loss was bilateral and in the frequency range of 2000-4000 Hz, with a mean of 3200 +/- 836.66 Hz. There were no significant differences between SNHL and non-SNHL patients in age, sex, serum ferritin level, age of the first transfusion, starting age of deferoxamine infusion, or duration and dosage of deferoxamine therapy. It seems that SNHL is not directly related to the serum ferritin level or deferoxamine dosage and other factors, including genetic or constitutional characteristics, may be also related. On the other hand, this complication may occur with doses lower than 50 mg/kg/day of deferoxamine, so no dosage can be considered safe for this drug. Despite the results of this study, hearing evaluation of beta-thalassemia major patients by audiometry is recommended because of the importance of this complication and the consequent disabilities.

The Incidence of Ototoxicity in Patients Using Iron Chelators

“…Ototoxicity was seen at an older age in our study and, consistent with previous studies, there was no relationship of ferritin or pre-tx Hb level between the ototoxicity and non-ototoxicity groups (p=0.705) [1,4,6] . Ototoxicity was, however, significantly associated with duration of DFO use (Pearson Chi-Square test, p<0.05).…”

“…Ambrosetti et al [12] reported that there was no correlation between ototoxicity and age or ferritin level. Similarly, Shamsian et al [1] reported no relationship between ferritin level, duration of DFO therapy, or dosage (48.9±9.6 mg/kg/day) of DFO therapy with hearing loss; also, Styles and Vichinsky [14] found no significant difference between ototoxicity and non-ototoxicity groups with respect to age, DFO dose, length of chelation, or ferritin level. In contrast, Porter et al [9] concluded that DFO ototoxicity was related to high dosage and low ferritin levels, and in a large series (283 cases) analyzed by Faramarzi et al [4] the incidence of ototoxicity, occurring only in those taking doses greater than 50 mg/kg/day, was 3.5%.…”

“…In some previous studies, the minimum sensorineural hearing loss to conclude ototoxic effects of DFO was 15 dB and above at any audiometry frequency, while in others, it was 20 dB and above [1,6] . However, ototoxicity evaluation scales will give more accurate results in the assessment of drug ototoxicity.…”

“…Deferoxamine (DFO; Desferal 500 mg; Novartis, Stein, Switzerland) was the first and, until recently, the preferred iron-chelating drug [1,2] . However, there have been several reports of DFO ototoxicity [1][2][3][4][5][6] , especially with long-term use and at higher doses. In recent years, deferiprone (Ferriprox 500 mg; Ontario, Canada) and deferasirox (Exjade 500 mg; Novartis, Stein, Switzerland) have largely replaced DFO due to their ease of use, as they can be taken orally.…”

Olfactory Dysfunction in β Thalassemia Major Patients Treated With Iron-Chelating Agents

“…1 Regular blood transfusions are carried out in patients with BTM starting from childhood to improve quality of life, and increase survival. 2 Regular blood transfusions result in iron deposition, in other words secondary chromatosis, which causes various organ dysfunctions, such as hepatic fibrosis and cirrhosis, hyperpigmentation of skin, diabetes mellitus, hypogonadism, pulmonary dysfunction, and cardiac disorders. 3 Iron-chelating agents are used to decrease complications related to transfusion-induced hemochromatosis in patients BTM.…”