A Case of Gitelman Syndrome with an Uncommon Presentation of Normomagnesemia

Background: Gitelman Syndrome (GS), also known as familial hypokalemia-hypomagnesemia, is an autosomal recessive renal tubular disorder that impacts sodium retention to electrolyte imbalance. It is a rare salt-losing tubulopathy that has a 1:40,000 prevalence. The disorder is mostly associated with symptoms including hypokalemic metabolic alkalosis with hypomagnesemia and low urinary calcium excretion.

Case Information: An8-year-old female with a history of ADHD and bipolar disorder presents to her primary care clinic for initial concerns about low potassium and high cholesterol after getting routine lab work done outside of her primary care clinic. She had been receiving treatment at a mental health facility and had routine bloodwork done for her medications. The patient was referred to her primary care provider to follow up on the lab work. Her guardian had concerns about the child’s short stature and a bone age X-ray and labs were ordered. Her guardian also stated that her paternal grandmother had hypokalemia of unknown etiology. Her lab result showed hypokalemia (2.7 mmol/L) and hypercholesterolemia (192 mg/dL), so she was sent to a children’s hospital emergency room for immediate management. In the ER, the patient again had hypokalemia (2.5 mmol/L), elevated anion gap (21 mmol/L), and positive ketones. Her EKG showed prolonged QT interval and she was admitted to the hospital for further management. After receiving a potassium replacement, her EKG normalized, and the cardiologist cleared her for further follow-up. Genetic testing confirmed that she has Gitelman Syndrome, specifically a mutation in the SLC12A3 gene. Interestingly, Gitleman Syndrome usually presents with hypomagnesemia, but in this case, the patient only had hypokalemia and not hypomagnesemia. The patient was discharged with oral potassium and has been following up with a nephrologist on a regular basis.

Conclusions: This case study showcases a rare case of Gitelman Syndrome with an unusual presentation of normomagnesemia. Future research should be conducted to solidify diagnostic criteria, evaluate abnormalities, and assess the long-term effects of the disease.