Hereditary hypophosphatemic rickets with hypercalciuria: case report

Area of Science:

• Nephrology
• Genetics
• Endocrinology

Background:

• Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is a rare autosomal recessive disorder.
• It is characterized by renal phosphate wasting and hypercalciuria, leading to rickets and nephrocalcinosis.

Observation:

• A 50-year-old male presented with recurrent kidney stones, nephrocalcinosis, and signs of rickets.
• Biochemical tests revealed severe renal phosphate loss, hypophosphatemia, high 1,25(OH)2D, low PTH, and hypercalciuria.
• Genetic analysis identified a homozygous mutation in the SLC34A3 gene, confirming HHRH.

Findings:

• The patient exhibited symptoms secondary to nephrocalcinosis, including chronic renal failure and incomplete renal tubular acidosis.
• His children were heterozygous carriers, with two showing hypercalciuria despite being asymptomatic.
• The identified SLC34A3 mutation affects the sodium-dependent phosphate cotransporter (NaPi-IIc) in the proximal tubule.

Implications:

• Accurate diagnosis of HHRH is crucial for appropriate management, differentiating it from other hypophosphatemic rickets forms.
• Phosphorus supplementation is key, while calcitriol administration may worsen nephrocalcinosis.
• Early intervention can prevent long-term bone and renal sequelae associated with HHRH.