Persistent hyperkalaemia in vitamin B12 unresponsive methylmalonic acidaemia

Area of Science:

• Pediatric Nephrology
• Endocrinology
• Metabolic Disorders

Background:

• Methylmalonic acidaemia is an inherited metabolic disorder that can lead to serious health complications.
• Vitamin B12 unresponsive forms present unique challenges in management.
• Hyperkalaemia and renal dysfunction are potential, though less common, sequelae.

Observation:

• A pediatric patient with vitamin B12 unresponsive methylmalonic acidaemia presented with persistent hyperkalaemia (serum potassium 6.8 mmol/L) and hyperuricaemia.
• Azotaemia was noted one year later, followed by comprehensive renal function studies at age 5.
• Studies revealed hyperaldosteronism, decreased creatinine clearance, impaired distal sodium reabsorption, and inadequate urine concentrating ability.

Findings:

• The hyperkalaemia was attributed to a combination of factors: reduced sodium reabsorption potentially limiting potassium excretion, decreased glomerular filtration rate, and excess dietary potassium intake.
• Renal tubular dysfunction played a significant role in the electrolyte imbalance.

Implications:

• This case highlights the importance of monitoring renal function and electrolyte balance in patients with methylmalonic acidaemia, even in vitamin B12 unresponsive cases.
• Dietary potassium restriction is a crucial and effective management strategy for hyperkalaemia in this context.
• Understanding the interplay between metabolic disorders and renal function is vital for comprehensive patient care.