Aim: to study the calcium level in the urine, serum and hairs and to assess the diagnostic value of the calcium level in various biosubstrates in patients with calcium and non-calcium stones.
Materials and methods: a total of 99 patients with urinary stone disease were included in the study. A diagnostic value of calcium level in biosubstrates according to the chemical analysis of stone composition performed using qualitative chemical reactions and microcrystalloscopy was evaluated.
Results: Urinary level of calcium and oxalate is proved to have high diagnostic value in patients with calcium nephrolithiasis (specificity 93.9% and 96.9%, and positive predictive value 88.2% and 97.2%, respectively). The specificity and positive predictive value of the calcium level in the hairs was 81.2% and 87.2%, respectively.
Conclusion: A comprehensive study of the elemental spectrum in urine, hair, and serum increases the diagnostic value of the evaluation of calcium, determined by the type of studied biosubstrate and stone type in patients with nephrolithiasis.

Keywords: hairs, diagnostic value, serum, nephrolithiasis, calcium, urine