Hypothyroidism following allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia

Hypothyroidism may complicate allogeneic hematopoietic stem cell transplantation (allo-HSCT); we therefore analyzed risk factors in this study.

We studied 229 patients with acute myeloid leukemia (AML) who underwent an allo-HSCT between 2003 and 2013 with different conditioning regimens (myeloablative, reduced-intensity, chemotherapy-based, or total body irradiation-based). Thyroid-stimulating hormone (TSH) and free thyroxine levels (fT4) were available in 104 patients before and after allo-HSCT.

The median age at transplantation (n=104) was 47 (IQR 40-59)], 37 (35.6%) patients were female, and the overall mortality was 34.6% (n=36). After a median follow-up period of 47 (IQR 25-84) months, overt hypothyroidism (basal TSH>4.49mIU/l, FT4<11.6pmol/l) was observed in 4 patients (3.8%) and subclinical hypothyroidism (basal TSH>4.49mIU/l, normal fT4) was observed in 20 patients (19.2%). Positive thyroperoxidase (TPO) antibodies were found in 5 (4.8%) patients. A total of 13 patients (12.5%) were treated with thyroid hormone replacement. Acute graft-versus-host disease (aGvHD) ≥grade 2 occurred in 55 (52.9%) and chronic GvHD (cGvHD) in 74 (71.2%) of the patients. The risk of developing hypothyroidism was higher in the patients with repeated allo-HSCTs (P=0.024) and with positive TPO antibodies (P=0.045). Furthermore, the development of overt hypothyroidism was inversely proportional to age (P=0.043). No correlation was found with GvHD, HLA-mismatch, total body irradiation, and gender.

After allo-HSCT, a significant number of patients experience thyroid dysfunction, including subclinical and overt hypothyroidism. Long-term and continuous follow-up for thyroid function after HSCT is important to provide timely and appropriate treatment.