Hyponatremia and Acute Kidney Injury as a Consequence of Malnutrition: A Case Report

This case presents how malnutrition due to underlying psychiatric disease can cause severe, chronic hyponatremia and acute kidney injury. A 31-year-old man was admitted due to fatigue. Blood tests displayed hyponatremia of 101 mmol/L and acute kidney injury. The patient had restricted himself to a uniform diet mainly consisting of rice boiled without salt. Isotone and hypertonic sodium chloride were used to secure a controlled rise in the sodium level. Despite fluid therapy, a delayed response in improvement in renal function was seen. After discharge, the patient started a balanced diet and the sodium level was almost normalized. Renal function eventually recovered. Long-term malnutrition may affect the tubular function of the kidney. Severe hyponatremia, other electrolyte disturbances, and protein and vitamin deficiency can be factors that interact in this pathogenesis. Resuming a normal diet may allow the kidney’s function to return to normal despite malnutrition during months.