Medullary Sponge Kidney: A Case Study of Extreme Metabolic Derangements
International Journal of Academic Medicine
Introduction: Medullary sponge kidney (MSK) is a disorder characterized by cystic dilation of distal collecting tubules, with complications including distal tubular acidosis, recurrent urinary tract infections, urolithiasis, and medullary nephrocalcinosis. Due to the rarity of MSK, its effects on the metabolite levels of patients are not widely noted and treatment guidelines for metabolic derangements due to MSK are limited. In this case report, we present an example of extreme metabolic derangements seen in an MSK patient due to her underlying disease. Methods: The patient is a 42-year-old female with past medical history stage 4 chronic kidney disease secondary to medullary sponge kidney, recurrent urinary tract infection history and kidney stones, and chronic hypokalemia receiving biweekly potassium infusions who presented on admission with intractable nausea and vomiting and muscle weakness. She also experienced symptoms consistent with a urinary tract infection. On admission, her vitals were significant for tachycardia and hypotension, and her electrocardiogram showed QT prolongation. Her labs were significant hyponatremia, hypokalemia, hypochloremia, low bicarbonate, high anion gap, and high creatinine. Her venous blood gas showed significant acidosis. She has had frequent admissions in the past for acidosis and electrolyte disturbances. Her CT abdominal and pelvic scan showed multiple punctate calculi bilaterally which is consistent with medullary nephrocalcinosis from her history of medullary sponge kidney. The urinalysis showed moderate blood, leukocytes and bacteria, innumerable white blood cells, and trace protein. Results: From her presentation, it was suspected she had a urinary tract infection which caused intractable nausea and vomiting, and she was appropriately managed. The nephrology team was consulted for further management of her severe electrolyte derangements, caused by her chronic kidney disease secondary to medullary sponge kidney (Figure 1, Table 1). Over the hospital admission, the hyponatremia and bicarbonate level improved, the anion gap closed, and the metabolic acidosis was resolved. Her creatinine improved. Her potassium level was consistent throughout the hospital course, which is found to be her baseline. Due to having medullary sponge kidney, she was consistently anemic. The patient symptomatically improved. Upon discharge, the plan was for her to have a repeat basic metabolic panel after a couple of days and to follow up with her outpatient nephrologist, hematologist and primary care provider. She continued to receive potassium supplementation given her chronic hypokalemia, and she was scheduled to have a catheter placed for dialysis access so she can begin outpatient dialysis. Conclusion: Our case emphasizes the importance of continuous follow-up and management of patients with medullary sponge kidney, especially since they are at high risk for readmission. Providers should also be aware that patients with MSK can live with baseline significant metabolic abnormalities despite aggressive inpatient treatment, due to the chronicity of their electrolyte derangement. Patient and physician education on medullary sponge kidney is vital to prevent recurrent complications, provide appropriate management, and maintain continuity of care.
Sun, Michael L.; Joseph, Crystal; Emengo, Ikechukwu; Shah, Pallav; and Krishnamurthy, Mahesh, "Medullary Sponge Kidney: A Case Study of Extreme Metabolic Derangements" (2022). Center for Medical Imaging & Interventional Radiology @SLUHN Articles & Publications. 6.