Electrolyte monitoring in patients undergoing peripheral blood stem cell collection

In recent years peripheral blood stem cell (PBSC) collection for allogeneic or autologous transplantation has experienced an increased use in the onco -hematological setting. The latest generation cell separators allow a satis factory and safe PBSC collection. Nevertheless, as in all therapeutic apher esis procedures, patients may experience procedure-related side-effects, ma inly vasovagal reactions or symptoms related to hypocalcemia and/or hypomag nesemia. We investigated electrolyte changes in 18 patients, with a median age of 46 years (range 7-62), undergoing PBSC collection from January to Ap ril 1998. A significant decrease in total calcium in the final sample (9.65 +/- 0.7 mg/dL) with respect to the basal one (9.2 +/- 0.6 mg/dL, P < 0.05) was observed; also ionized calcium decreased markedly from the first sampl e drawn at +30 minutes: 1.22 +/-: 0.14 vs. 1.03 +/- 0.15 mmol/L (P < 0.05), and a highly significant difference emerged when basal value were compared to the final value: 1.22 +/- 0.14 vs. 0.94 +/- 0.13 mmol/L (P < 0.0001). S imilar findings affected potassium concentration: 4.1 +/- 0.4 vs. 3.3 +/- 0 .3 mEq/L (P < 0.0001). Three out of eighteen patients (16.7%) reached a fin al potassium level <3.0 mEq/L, and eight out of eighteen (44.5%) showed a p otassium concentration decrease >20% with respect to the basal value. A mil d metabolic alkalosis occurred during the procedure: pH increased from 7.35 +/- 0.02 to 7.43 +/- 0.028 (P < 0.001), and plasma bicarbonate concentrati on increased from 27.48 +/- 2.21 to 32.44 +/- 2.52 mmol/L (P < 0.01). Sodiu m and chloride did not differ in the final sample with respect to the basal sample. None of our patients experienced clinically relevant side effects related to severe electrolyte changes (i.e., >20% with respect to the basal value). Because our current therapeutic schedules include patients older t han 50 years in the PBSC collection and transplantation program and since i t is well known that subclinical myocardial disease may occur in up to 4% o f middle-aged males, we suggest that patients aged 50 or older undergoing P BSC collection procedures be carefully monitored in order to identify signi ficant electrolyte variation, especially if they present with low serum pot assium levels. However, further investigation of larger patient series are needed to determine the clinical relevance of serum potassium changes durin g apheresis. (C) 1999 Wiley-Liss, Inc.