Risk Factors of HHV6 Reactivation and Relationship Between Syndrome of Inappropriate Antidiuretic Hormone Secretion After Stem Cell Transplantation in Pediatric Patients

Abstract 4580

Many reports were seen about reactivation of human herpes virus 6 (HHV6) after stem cell transplantation (SCT) in adult patients, and this reactivation sometimes induce severe condition of patients. However, few reports were seen about pediatric patients. Therefore, we examined HHV 6 reactivation after stem cell transplantation in patients with children, retrospectively. The cases were 80 patients, 48 male, 32 female, and the median age was 6 years old (range 0–20 years old). Transplantations were 23 related bone marrow transplantations (BMT) or peripheral blood stem cell transplantations (PBSCT), 18 unrelated BMT, one related cord blood transplantation (CBT), 31 unrelated CBT, and seven autologous BMT or PBSCT. We analyzed HHV6 DNA samples of serum with these patients before SCT, 20 days and 40 days after SCT using PCR method. In addition, we analyzed relationship between HHV6 reactivation and syndrome of inappropriate antidiuretic hormone secretion (SIADH).

In samples of 20 days after SCT, 35.0% of samples were positive for HHV6 DNA. On the other hand, 2.5% and 5.0% were positive before SCT and 40 days after SCT, respectively. From 24 out of 28 samples, over 10E3 of HHV6 DNA were detected in positive samples. Factors associated with HHV6 reactivation were CBT, unrelated donor, malignant diseases, use of total body irradiation as conditioning, cyclosporine and methyl prednisolone as GVHD prophylaxis, acute GVHD (>grade 2), chronic GVHD and use of steroid using univariate analysis. Moreover, CBT was an only risk factor of HHV6 reactivation using multivariate analysis.

In 14 patients with SIADH, 78.6% of patients had HHV6 reactivation. On the other hand, 25.8% of patients had HHV6 reactivation in 66 patients without SIADH. This result was statistically significant (p<0.001).

From this analysis, we can understand HHV6 reactivation was seen in many patients with children. In addition, we thought about the possibility of SIADH is one symptom of the encephalopathy by the HHV6 reactivation.