Hereditary Hypophosphatemic Rickets with Hypercalciuria-Importance of Further Evaluation when Clinical Suspicion is...

Area of Science:

• Genetics
• Pediatrics
• Endocrinology

Background:

• Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is a rare autosomal recessive disorder.
• Mutations in the SLC4A3 gene cause HHRH, leading to diagnostic challenges due to evolving symptoms and initially normal biochemistry.
• Incorrect diagnosis can lead to contraindicated treatments, such as active vitamin D metabolites.

Purpose of the Study:

• To highlight the diagnostic challenges of HHRH, particularly in resource-limited settings.
• To emphasize the importance of repeated investigations in suspected HHRH cases.
• To present a case series illustrating the diagnostic evolution of HHRH.

Main Methods:

• Case report of two siblings with HHRH.
• Clinical presentation, biochemical, and urinary phosphate studies were analyzed.
• Treatment response to phosphate supplementation and potassium citrate was evaluated.

Main Results:

• The first child presented with rickets at 5.5 years, with abnormal bone profile but normal vitamin D; urinary phosphate studies confirmed HHRH.
• The second child initially had normal investigations at 1.5 years but developed worsening bowing by 2.5 years, with later findings consistent with HHRH.
• Both patients responded well to phosphate supplementation and potassium citrate.

Conclusions:

• HHRH diagnosis requires careful clinical suspicion and repeated investigations, even with initially normal biochemical parameters.
• Timely and accurate diagnosis is critical to avoid inappropriate treatments.
• This case series underscores the importance of persistent diagnostic evaluation in rare genetic conditions, especially in resource-limited environments.