Complications
The normal thirst response is protective against the development of hypernatraemia in patients with AVP-D or AVP-R. Hypernatraemia can occur if patients have impaired free access to water.
Mild to moderate hypernatraemia may present with irritability, restlessness, lethargy, muscle twitching, spasticity, or hyper-reflexia.
The presence of delirium, seizures, or coma suggests severe hypernatraemia.
Treatment includes the correction of serum sodium via oral and/or intravenous fluids. Serial serum electrolyte and osmolality measurements should be obtained to assess response to therapy.
Some infants with arginine vasopressin resistance (AVP-R), in addition to the typical symptoms of polyuria and polydipsia, may exhibit vomiting, retching, unexplained fevers, lethargy, and irritability. Other possible features include constipation, diarrhoea, and poor feeding, which can contribute to inadequate growth or weight gain.[74] Many individuals with childhood-onset AVP-R reach an adult height slightly below average or lower than expected, often due to suboptimal disease management or poor nutrition during childhood.[74]
Patients with AVP-R may develop bladder dysfunction in response to excess urine production. If unrecognised, this may lead to renal impairment. Monitoring with regular serum creatinine assessment and periodic renal and bladder ultrasound is recommended.[70]
If arginine vasopressin resistance is left untreated, severe dehydration can occur, and repeated episodes may lead to serious complications such as seizures, brain injury, developmental delays, and long-term physical or intellectual disability.[74] However, with early diagnosis and appropriate treatment, normal cognitive and developmental outcomes are typically achieved.[74]
Hyponatraemia is common in patients with chronic AVP-D who are on replacement desmopressin (also known as DDAVP).[73] Most of this hyponatraemia remains asymptomatic.
Treatment is through appropriate desmopressin dose adjustment. The prevalence of hyponatraemia is less in patients who practice ‘desmopressin escape’ once a week to allow an aquaresis.
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