The present invention pertains to the use of a peptide molecule consisting in a maturation product of SMR1 (Submandibular rat protein 1) of structural formula QHNPR, as well as the biologically active derivatives of the said peptide, for preventing or treating diseases associated with a mineral ion imbalance in a human or an animal body. More particularly, the present invention relates to the therapeutic use of the above-cited molecules for preventing or treating an hydro-mineral imbalance in organs and tissues such as kidney, bone, dental enamel, dental ivory, gut matrix, pancreas or glandular gastric mucosa. This invention also deals with therapeutic compositions comprising a pharmaceutically active amount of the above-described therapeutic molecules as well as with therapeutic methods using the said therapeutic compositions. Finally, the present invention relates to processes for selecting ligand molecules that possess an agonist or an antagonist biological activity on the target receptor of the QHNPR pentapeptide as well as to the selected ligand molecules themselves.