[Transitory pseudohypoparathyroidism in the newborn infant]

Area of Science:

• Pediatrics
• Endocrinology
• Metabolic Disorders

Background:

• Pseudohypoparathyroidism (PHP) is a rare genetic disorder characterized by resistance to parathyroid hormone (PTH).
• Transitory pseudohypoparathyroidism presents with hypocalcemia and hyperphosphatemia, mimicking permanent forms but with potential for spontaneous resolution.
• Standard vitamin D therapy may be insufficient for managing metabolic disturbances in infants with PHP.

Observation:

• Two young infants presented with clinical and biochemical features of transitory pseudohypoparathyroidism.
• Initial treatment with high-dose vitamin D failed to normalize serum calcium and phosphate levels.
• Serum parathormone levels were within the normal range despite electrolyte imbalances.

Findings:

• Administration of 1.25-(OH)2-D3 (calcitriol) at doses of 0.25 and 0.5 micro-grams effectively corrected hypocalcemia and hyperphosphatemia.
• Urinary cyclic adenosine monophosphate (cAMP) excretion levels served as a biomarker to distinguish between transient and permanent forms of PHP.
• Urinary cAMP levels of 5-10 nmol/mg creatinine indicated the appropriate time to discontinue treatment in the transitory form.

Implications:

• 1.25-(OH)2-D3 is a highly effective therapeutic agent for managing metabolic derangements in infants with transitory pseudohypoparathyroidism.
• Monitoring urinary cAMP excretion is crucial for guiding treatment duration and preventing over-treatment in transitory PHP.
• This study highlights the importance of targeted therapy with active vitamin D analogs in specific pediatric endocrine disorders.