AJUDA COM FORMULA

procedure TForm1.GFR_CKD_EPI_fx;
type
  TCreatinine_unit = record
      Coefficient: double;
      Fit: double;
      Name: string;
    end;
const
  Serum_creatinine_unit: array[0..3] of TCreatinine_unit = (
    (Coefficient: 0.0113122171945701; Fit: 0;Name: 'mcmol/L_Cr'),
    (Coefficient: 1; Fit: 0;Name: 'mg%_Cr'),
    (Coefficient: 1; Fit: 0;Name: 'mg/dL_Cr'),
    (Coefficient: 11.3122171945701; Fit: 0;Name: 'mmol/L_Cr')
  );
var
  doCalc: boolean;
  rbchk: boolean;
  Sex, Race, alpha, kappa: double;
  Age: integer;
  unit_parts: TCreatinine_unit;
  ParamSerum_creatinine, Serum_creatinine: double;
  dp: integer;
  GFR: double;

  function fixDP(r: double; dps: integer): string;
  var
    msign: string;
    x: double;
    m: string;
  begin
    msign := '';
    if (r < 0) then msign := '-';
    x := abs(r);
    if (x > power(10, 21)) then
    begin
      result := msign + FloatToStr(x);
      exit;
    end;
    m := FloatToStr(round(x * power(10, dps)));
    if (dps = 0) then
    begin
      result := msign + m;
      exit;
    end;
    while (length(m) <= dps) do m := '0' + m;
    result := msign + copy(m, 0, length(m) - dps) + '.' + copy(m, length(m) + 1 - dps);
  end;
begin
  doCalc := true;
  Sex := 0;
  alpha := 0;
  kappa := 0;
  Race := 0;

  rbchk := (RadioGroupSex.ItemIndex > -1);
  {RadioGroupSex.Items = [Mulher, Homem]}
  if RadioGroupSex.ItemIndex = 0 then
  begin
    Sex := 1.018;
    alpha := -0.329;
    kappa := 0.7;
  end
  else
  if RadioGroupSex.ItemIndex = 1 then
  begin
    Sex := 1;
    alpha := -0.411;
    kappa := 0.9;;
  end;

  if (not rbchk) then doCalc := false;

  rbchk := (RadioGroupRace.ItemIndex > -1);
  {RadioGroupRaca.Items = [Branco ou outro (1); Negro (1.159)]}
  if RadioGroupRace.ItemIndex = 0 then
    Race := 1
  else
  if RadioGroupRace.ItemIndex = 1 then
    Race := 1.159;

  if (not rbchk) then doCalc := false;

  Age := StrToIntDef(MaskEditAge.Text,0);
  ParamSerum_creatinine := StrToFloatDef(MaskEditSerumCreatinine.Text,0);
  {ComboBoxSerumCreatinine.Items = [mcmol/L, mg%, mg/dL, mmol/L]}
  unit_parts := Serum_creatinine_unit[ComboBoxSerumCreatinine.ItemIndex];
  Serum_creatinine := ParamSerum_creatinine * unit_parts.Coefficient + unit_parts.Fit;
  {ComboBoxDP.Items = [0,1,2,3]}
  dp := StrToIntDef(ComboBoxDP.Items[ComboBoxDP.ItemIndex],0);
  GFR :=  141
          * math.power(math.min(Serum_creatinine/kappa, 1), alpha)
          * math.power(math.max(Serum_creatinine/kappa, 1), -1.209)
          * math.power(0.993,Age)
          * Sex
          * Race;

  if (doCalc) then MaskEditGRF.Text := fixDP(GFR, dp);
end;