A computer-based method for automatically determining total body albumin of a living being comprising the steps of: determining a baseline of expected ratio of amount of albumin in an intravascular system of the living being to amount of albumin in an extravascular system of the living being, wherein the baseline is a locally smoothed exponential fit baseline curve based on a locally weighted scatterplot smoothing analysis of ratios of count values of radio-labeled albumin over a period of time after the radio-labeled albumin is initially injected into a plurality of living beings to count values of radio-labeled albumin at a time when the radio-labeled albumin is initially injected into a plurality of living beings; receiving input of serum albumin concentration of the living being; calculating, using one or more processors, plasma volume of the living being based on detected counts of radio-labeled albumin injected into the living being; calculating, using one or more processors, an amount of intravascular albumin within the living being based on the calculated plasma volume and the determined albumin concentration; calculating, using one or more processors, an observed ratio of amount of albumin in the intravascular system of the living being to amount of albumin in the extravascular system of the living being at a first time after injecting the radio-labeled albumin into the living being by calculating a ratio between observed count data at the first time to count data at time zero; and calculating, using one or more processors, the total body albumin of the living being based on the calculated intravascular albumin, the calculated observed ratio of amount of albumin in the intravascular system of the living being to amount of albumin in the extravascular system of the living being at the first time, and the baseline of expected ratio of amount of albumin in the intravascular system of the living being to amount of albumin in the extravascular system of the living being at the first time, wherein the calculated observed ratio is known to exhibit a consistent deviation from the baseline, and wherein the step of calculating the total body albumin is performed before the rate of loss of albumin in the intravascular system of the living being to the extravascular system of the living being is stabilized according to a log-linear relationship. determining a baseline of expected ratio of amount of albumin in an intravascular system of the living being to amount of albumin in an extravascular system of the living being, wherein the baseline is a locally smoothed exponential fit baseline curve based on a locally weighted scatterplot smoothing analysis of ratios of count values of radio-labeled albumin over a period of time after the radio-labeled albumin is initially injected into a plurality of living beings to count values of radio-labeled albumin at a time when the radio-labeled albumin is initially injected into a plurality of living beings; receiving input of serum albumin concentration of the living being; calculating, using one or more processors, plasma volume of the living being based on detected counts of radio-labeled albumin injected into the living being; calculating, using one or more processors, an amount of intravascular albumin within the living being based on the calculated plasma volume and the determined albumin concentration; calculating, using one or more processors, an observed ratio of amount of albumin in the intravascular system of the living being to amount of albumin in the extravascular system of the living being at a first time after injecting the radio-labeled albumin into the living being by calculating a ratio between observed count data at the first time to count data at time zero; and calculating, using one or more processors, the total body albumin of the living being based on the calculated intravascular albumin, the calculated observed ratio of amount of albumin in the intravascular system of the living being to amount of albumin in the extravascular system of the living being at the first time, and the baseline of expected ratio of amount of albumin in the intravascular system of the living being to amount of albumin in the extravascular system of the living being at the first time, wherein the calculated observed ratio is known to exhibit a consistent deviation from the baseline, and wherein the step of calculating the total body albumin is performed before the rate of loss of albumin in the intravascular system of the living being to the extravascular system of the living being is stabilized according to a log-linear relationship.