Endocrine Abstracts

Hypothalamic neuropeptides as biomarkers for water-electrolyte disturbances. Introduction Diabetes insipidus is a rare condition characterized by excretion of large amounts of dilute urine and increased thirst. Nephrogenic diabetes insipidus (NDI) is caused by the inability of the kidneys to concentrate urine in response to vasopressin.

Aim: The aim of our case report is to present the patient with NDI and to report the data on physiological changes in hypothalamic neuropeptides such as copeptin, oxytocin, apelin, brain natriuretic peptide (BNP) in patient with NDI.

Material and methods: 21-year-old male patient was admitted to the hospital with chief complaint of increased thirst and urinary frequency.

Results: In accordance with the results of indirect water-deprivation test NDI was diagnosed in our patient due to maximum urine osmolality of less than 76 mOsm/kg, plasma osmolality 302 mOsm/kg, maximum plasma sodium was 148 mmol/l, and no change in urine osmolality after administration of 2 mg of s.c. desmopressin. Copeptin, oxytocin, apelin, BNP after 8-h fluid restriction accounted for: 0.844 ng/ml (0.178-2.578 ng/ml), 5.694 ng/ml (0-12.821 ng/ml), 1.476 ng/ml, (0.620-2.095 ng/ml),1225.86 pg/ml (646.3-2033.4 pg/ml) and at the peak of dehydration (for 16 h) accounted for: 1.058 ng/ml, 6.176 ng/ml, 1.346 ng/ml, 973.93 pg/ml.

Conclusion: Our data confirm a commensurate increase in the levels of copeptin and oxytocin with a reciprocal decrease in the concentrations of apelin and BNP against the background of additional dehydration, which can later be used for differential diagnostic procedures for the syndrome of polydipsia-polyuria.