Calcium in blood plasma circulates in two main states: The non-diffusible protein-bound calcium which constitutes approximately 45% of the total plasma calcium and the diffusible free calcium fraction which can be further subdivided into complexed calcium and ionised calcium. The ionised calcium fraction is the physiologically active form. Albumin is the protein, which binds approximately 80% of the protein-bound calcium fraction in plasma, therefore any changes in plasma albumin concentration will directly influence the plasma total calcium concentration. To demonstrate this hypothesis, a study was done on patients with decreased plasma albumin concentrations to determine the effect on their total calcium, ionised calcium and corrected total calcium concentrations. Our study clearly illustrates that ionised calcium and corrected total calcium concentrations are better indicators of calcium homeostasis in patients with hypoproteinaemia, than total calcium concentrations alone. Medical staff therefore, cannot only rely on total calcium concentrations in these patients.