A method for computing erythropoiesis-stimulating agents (ESAs) dosing intravenously, subcutaneously, or orally, for treating anemia in a human subject, including: providing a previously obtained sample from said subject; determining a value of a haemoglobin concentration as at least one biochemical property related to an anemia status in said sample; determining a difference between said value of said haemoglobin concentration and a predetermined optimal value for said haemoglobin concentration; and, employing a computing element with a mathematical algorithm to calculate a required ESA dosage based on said difference, wherein said algorithm i) includes an approximated discrete-time integrator providing an output y(kT) at a sample time kT related to a current input u(kT) by a difference equation of y kT = u kT + y kT − T, where y(kT - T) is the output at the previous sample time, and wherein the input to the approximated discrete-time integrator is said measured haemoglobin concentration, and the output of the approximated discrete-time integrator is a concentration of the erythropoiesis-stimulating agent, ESA, and ii) maintains predetermined target performance criteria for a range of biochemical property values in a plurality of predetermined physiological factors affecting said value of said haemoglobin concentration. providing a previously obtained sample from said subject; determining a value of a haemoglobin concentration as at least one biochemical property related to an anemia status in said sample; determining a difference between said value of said haemoglobin concentration and a predetermined optimal value for said haemoglobin concentration; and, employing a computing element with a mathematical algorithm to calculate a required ESA dosage based on said difference, wherein said algorithm i) includes an approximated discrete-time integrator providing an output y(kT) at a sample time kT related to a current input u(kT) by a difference equation of y kT = u kT + y kT − T, where y(kT - T) is the output at the previous sample time, and wherein the input to the approximated discrete-time integrator is said measured haemoglobin concentration, and the output of the approximated discrete-time integrator is a concentration of the erythropoiesis-stimulating agent, ESA, and ii) maintains predetermined target performance criteria for a range of biochemical property values in a plurality of predetermined physiological factors affecting said value of said haemoglobin concentration. i) includes an approximated discrete-time integrator providing an output y(kT) at a sample time kT related to a current input u(kT) by a difference equation of y kT = u kT + y kT − T, where y(kT - T) is the output at the previous sample time, and wherein the input to the approximated discrete-time integrator is said measured haemoglobin concentration, and the output of the approximated discrete-time integrator is a concentration of the erythropoiesis-stimulating agent, ESA, and ii) maintains predetermined target performance criteria for a range of biochemical property values in a plurality of predetermined physiological factors affecting said value of said haemoglobin concentration.