Hypothyroidism in induction chemotherapy of children with acute lymphoblastic leukaemia: A single‐centre study

Hypothyroidism as a long-term complication in cancer survivors has been an issue, but few studies have focused on changes in thyroid hormone levels during chemotherapy for leukaemia. This retrospective study was conducted to assess the characteristics of children with acute lymphoblastic leukaemia (ALL) and hypothyroidism during induction chemotherapy and to investigate the prognostic value of hypothyroidism in ALL. Patients with a detailed thyroid hormone profile at ALL diagnosis were enrolled. Hypothyroidism was defined as low serum levels of free tetraiodothyronine (FT4) and/or free triiodothyronine (FT3). The Kaplan-Meier method was used to create survival curves, and multivariate Cox regression analysis was used to screen prognostic factors associated with progression-free survival (PFS) and overall survival (OS). There were 276 children eligible for the study, and 184 patients (66.67%) were diagnosed with hypothyroidism, including 90 cases (48.91%) with functional central hypothyroidism and 82 cases (44.57%) with low T3 syndrome. Hypothyroidism was correlated with the dosages of L-Asparaginase (L-Asp) (P = .004) and glucocorticoids (P = .010), central nervous system (CNS) status (P = .012), number of severe infections (grade 3, 4 or 5) (P = .026) and serum albumin level (P = .032). Hypothyroidism was an independent prognostic factor for PFS in ALL children (P = .024, 95% CI: 1.1-4.1). We conclude that hypothyroidism is commonly present in ALL children during induction remission, which is related to chemotherapy drugs and severe infections. Hypothyroidism was a predictor of poor prognosis in childhood ALL.