# Persistent Hypomagnesemia in the Context of Refeeding and Supplementation: A Case Report

## TL;DR

A young woman with anorexia nervosa had ongoing low magnesium levels despite treatment, highlighting the need for further investigation into unusual causes of electrolyte issues during recovery.

## Contribution

This case report highlights a rare presentation of persistent hypomagnesemia during refeeding and identifies novel genetic variants not previously linked to renal disorders.

## Key findings

- A patient with anorexia nervosa experienced persistent hypomagnesemia despite magnesium supplementation.
- Genetic testing revealed variants in PKD1, SCNN1G, and SMARCAL1 genes not associated with known renal disorders.
- The case underscores the importance of exploring alternative causes for refractory electrolyte abnormalities during refeeding.

## Abstract

Refeeding syndrome is characterized by electrolyte imbalances that occur during nutritional replenishment in malnourished patients. Hypomagnesemia is a potential complication.

We present a unique case of a female, young adult patient with anorexia nervosa who experienced persistent hypomagnesemia during inpatient refeeding that did not resolve with magnesium supplementation. Extended diagnostic evaluation included genetic testing that revealed heterozygous variants of uncertain significance in the PKD1 and SCNN1G genes as well as a pathogenic variant in the SMARCAL1 gene. These variants are not currently associated with a known renal disorder.

While the extensive work-up for persistent hypomagnesemia in the context of appropriate supplementation did not yield a definitive diagnosis, this case emphasizes the need to pursue alternative etiologies and treatments of unexpectedly refractory electrolyte abnormalities during the course of refeeding.