P-338: High frequency of electrolyte derangement and low frequency of transfusion requirement post melphalan autologous bone marrow transplant – a single center experience

Introduction:
Melphalan autologous stem cell transplant (ASCT) is an important consolidation therapy in Multiple Myeloma (MM). In our center, patients who are discharged after neutrophil engraftment are followed up in regular intervals to monitor their blood counts and electrolytes. The follow up (FU) intervals, including blood tests, are twice weekly for the first two weeks followed by weekly FUs until a clinical review. We conducted a retrospective audit to monitor the effectiveness of this practice.

Methods:
We included patients who underwent melphalan ASCT for MM between January to December 2022. Blood parameters (Full blood counts, magnesium, potassium, and calcium), blood product transfusions, and electrolyte replacements were collected electronically from the date of discharge for 12 weeks.

Results:
50 patients were included in the analysis. 2.19% of Haemoglobin (Hb) values fall below our threshold of transfusion at 80 g/L. 7/50 (14%) patients required red cell blood (RBC) transfusion. Most transfusions were given at Hb values >= 70 g/L. 4/7 patients who were transfused had active infection at the time of infections. Most RBC transfusions occurred within the first two weeks post-discharge. One patient required RBC transfusion at week 5 associated with infection. Only one patient required 3 units of RBC transfusions, which was received between weeks 9 and 11 post discharge. This patient had COVID-19, and also received platelet transfusion. One other patient with COVID-19 infection and minor gum bleeding required platelet transfusion at week 12 post discharge. 4.29% of patients had neutrophil values below 0.5 x 10⁹/L.



We observed 5.87% of potassium values fall below 3.5 mmol/L. This led to potassium replacement in 64% of the patients. 5.83% of Calcium values were below 2.15 mmol/L. This led to calcium replacement in 68% of the patients. 11.2% of Magnesium values fell below 0.70. This led to magnesium replacement in 24% of the patients. Most of the electrolyte replacements were oral and done within the first week.

Conclusions:
A high proportion of RBC, and all of platelet transfusions, were related to active infections, especially COVID-19. We observed high rate of electrolyte replacements in our cohort. This is likely related to diarrhoea and poor nutrition that most patients continue to experience after discharge from hospital. Hypokalaemia around the time of neutrophil engraftment have previously been reported (genesis syndrome).



The findings of this retrospective audit suggested that most patients after Melphalan ASCT do not require blood product support. They may be followed up less intensively in the absence of infection. Some patients may require G-CSF support at home. Furthermore, in view of high potassium and calcium replacement rates after discharge, these patients may benefit from prophylactic electrolyte replacements. This may allow a faster ‘bleed and go’ service that may reduce the time spent in hospital. Further work will be required to test these two hypotheses.