Nephrogenic diabetes insipidus – rare clinical cases

Nephrogenic diabetes insipidus is an orphan disease characterized by the kidneys' inability to concentrate urine due to insensitivity of the distal nephron to antidiuretic hormone. Primary (hereditary) nephrogenic diabetes insipidus is often diagnosed in childhood and is associated with mutations in the AVPR2 and AQP2 genes. Secondary nephrogenic diabetes insipidus, in most cases, is identified in adult patients against the backdrop of diseases that impair renal concentrating function, therapy with agents that suppress AQP2 expression, and metabolic disorders, such as hypokalemia and hyperkalemia. In congenital abnormalities of the urinary system, secondary nephrogenic diabetes insipidus may also develop in early childhood due to impaired urodynamics. The clinical presentation of the disease is characterized by a polyuria-polydipsia syndrome, which significantly depends on the degree of dehydration and the timely compensation of renal fluid losses through adequate water intake. In severe cases, serious complications may arise, including hypernatremic dehydration and delays in physical and psychomotor development in young children. Given the diversity of potential clinical manifestations, the diagnosis of nephrogenic diabetes insipidus poses a challenging task in medical practice. This article describes two clinical cases of patients with genetically determined and secondary nephrogenic diabetes insipidus. Both men exhibit clinically similar symptoms from birth. However, given the differing etiology of the conditions, the treatment approaches vary. Timely detection of the condition and an appropriate therapeutic strategy can significantly enhance the quality of life for patients and prevent serious complications.