Background: Lysinuric protein intolerance (LPI) is an autosomal recessive cationic amino acid transport defect characterized by episodes of postprandial hyperammonemias and spontaneous protein aversion. Subnormal growth is common in spite of appropriate nutritional therapy. Growth hormone (GH) therapy promotes appetite, protein synthesis and accretion, but its possible growth-promoting effects and safety in patients with LPI are poorly known.
Methods: Four LPI children aged 7-16 years were treated with GH for a period of 3-4.5 years. Dietary intakes and plasma amino acid levels were analyzed frequently in addition to routine monitoring of GH therapy.
Results: Insulin-like growth factor-1 concentration was low and bone age was delayed in all LPI patients, but GH provocative test was pathological in only one of the patients. During the 3-4.5 years of GH therapy (dose 0.035-0.050 mg/kg/day), bone age did not catch up but height standard deviation score (SDS) improved by 0.7-1.8 SDS. There were no episodes of hyperammonemias.
Conclusions: Our data support safety and growth-promoting potential of long-term GH therapy in patients with LPI.