A case report of a man on peritoneal dialysis having intractable hyponatremia.

RATIONALE: Hyponatremia is one of the most common electrolyte disorders in patients on peritoneal dialysis (PD). It can be associated with severe consequences, higher morbidity and mortality. Therefore, hyponatremia should be assessed and monitored more carefully in these patients.

PATIENT CONCERNS: A 55-year-old male PD patient progressively developed intractable hyponatremia was admitted to our hospital.

DIAGNOSES: The observation that no significant salt was lost in kidney and PD drainage prompted us to seek the underlying reasons for malnutrition and chronic inflammation. And cancer and tuberculosis were further suspected, although the exact nature at last was not clearly determined due to the unfavorable prognosis.

INTERVENTIONS: The hyponatremia can hardly be improved by adjusting ultrafiltration close to zero, increasing sodium intake from 2.5 g to 7g, and nutrition counselling to maintain protein intake 0.9-1.2 g/kg/day and calorie intake 27-35 kcal/kg/day. Due to poor general situation, he received tentative anti-tuberculosis treatment instead of surgery for intracranial space-occupying lesion.

OUTCOMES: He died at home with conservative therapy.

LESSONS: It highlighted the challenge for differential diagnosis and treatment in the hyponatremia on PD patient.