An apparatus for use in whole body hypothermia includes a dialyzer having a blood side and a dialysate side separated by one or more dialysis membranes. A blood pump associated with the a blood circuit established on the blood side circulates blood through the dialyzer at high rates advantageous for hyperthermia treatments. A bypass is included whereby circulated blood can bypass the dialyzer. The bypass aids in preventing blood-side tensioning of dialyzer membranes thereby allowing proper membrane movement to assist in mixing a sorbent suspension circulated on the dialysate side of the dialyzer. A sorbent suspension composition for use as a dialysate in hemodialysis, especially when performed in conjunction with whole body hyperthermia, includes water, a surface adsorptive agent such as charcoal, a cation exchanger, and precipitated calcium phosphate. The precipitated calcium phosphate serves as a reservoir for calcium and phosphate ions to assist in controlling patient blood chemistries.