Background: Metabolic abnormalities have been reported in patients undergoing hematopoietic stem cell transplantation (HSCT). Potential causes, risk factors and outcomes of electrolyte imbalances have thoroughly been investigated. On HSCT recipients, multiple pathophysiologic contributers are inflicting electrolyte abnormalities, with special attention being paid to engraftment per se as an important contributer. Engraftment contribution to electrolyte imbalances has been reported for hypophosphatemia and for other electrolyte abnormalities in autologous setting. However in the allogeneic setting serum electrolyte level changes and the timing of any probable abnormalitiy are unknown.
Material and methods: We performed a retrospective study in order to evaluate the pattern of phosphorous, magnesium, potassium and uric acid serum changes, timing of any probable abnormality and their possible association with WBC and platelet engraftment in 65 allogeneic HCT recipients from day -9 to +32 after transplantation. Besides we assessed frequency and severity of the abnormalities.
Results: We observed a declining pattern of electrolyte concentrations with nadirs antedating WBC and platelet engraftments.
Phosphorous and potassium serum changes were correlated with natural logarithm of WBC and platelet level changes. Observed overall incidence of hypophosphatemia (9.2%) and hypomagnesemia (3%) was lower than those previously reported.
Conclusion: Abnormalities found reflect a combination of pathophysiologic mechanisms.
Occurrence of electrolyte nadirs antedating engraftment confirms increased consumption by rapidly replicating cells as a contributor in allogeneic setting and specifies a susceptible period requiring intensive monitoring. Considering high risk patients and managing various organ system complications lower incidence of some electrolyte abnormalities may be observed.

Keywords: allogeneic, engraftment, Electrolytes, Uric Acid