OBJECTIVE The human body is known to be composed of 24 elements, among which potassium, sodium and calcium are considered to be essential. These necessary components play a significant physiological role which includes regulation of the electrical and mechanical action of the heart. Abnormal concentration of the above-mentioned ions, i.e. water-electrolyte imbalance, may result in cardiac arrhythmias, muscle contraction disorders, disturbances of neuronal activity and influences the drugs activity. METHODS The study aimed at gathering and analyzing results of publicly available research which reported serum concentration of these ions. This information, together with an additional collection of data (gender, age, height, weight, measurement method), is presented in table form attached as supplementary material. RESULTS The serum ions concentrations means weighted by the study-specific sample sizes indicated statistically significant differences between males and females for all ions - K+ 4.21 and 4.09, Na+ 140.1 and 138.17, Ca2+ 2.42 and 2.31 respectively). CONCLUSIONS Obtained results correspond with the current laboratory reference values. As potassium, sodium and calcium follow the circadian rhythm, publications reporting serum concentration values were also collected and presented. Further studies are planned to describe such phenomenon in a form of the statistical model.