Growth hormone studies in lysinuric protein intolerance

Area of Science:

• Biochemistry
• Pediatrics
• Endocrinology

Background:

• Lysinuric protein intolerance (LPI) is a rare autosomal recessive metabolic disorder.
• Patients often present with growth retardation and skeletal abnormalities.
• Impaired amino acid transport affects protein metabolism and growth hormone secretion.

Observation:

• Two LPI patients, a 14-year-old boy and his 12-year-old sister, exhibited significant growth and bone age retardation.
• Growth hormone (GH) secretion showed variable responses to provocative tests: good response to glucagon-propranolol and arginine, but poor response to insulin.
• Following oral arginine hydrochloride administration, GH secretion improved significantly in response to both insulin and glucagon-propranolol.

Findings:

• Arginine supplementation enhanced the pituitary's responsiveness to GH secretagogues in LPI patients.
• Accelerated gains in height and weight were observed post-arginine administration.
• This suggests a potential role for arginine in mitigating growth deficits in LPI.

Implications:

• Arginine supplementation may be a viable therapeutic strategy for growth retardation in lysinuric protein intolerance.
• Understanding amino acid metabolism is crucial for managing complex metabolic disorders.
• Further research into the GH-arginine axis in LPI is warranted.