Lipid storage myopathy in a child with idiopathic short stature
E. Bivoleanu1, A. Constantinescu1, M. Alexianu2, C. Rusu1, I. Vasiliu1, J. Idriceanu1, I. Potorac1, R. Popovici1 & C. Vulpoi1
Introduction: Lipid storage myopathy (LSM) is characterized by increased lipid droplets in muscle fibers. Primary carnitine deficiency is the most frequent cause of LSM, clinical presentation ranging from asymptomatic to progressive muscle weakness or cardiomyopathy, carnitine supplementation being effective with remission of symptoms.
Case report: In february 2007 R.A. born in 1996 presented progressive muscle weakness with elevated muscular enzymes (LDH =1155 μI/ml n=125234, CPK=1082 μI/ml N=25195). Starting from a muscular biopsy, which suggested polymyositis, a glucocorticoid trial was initiated with partial amelioration followed by clinical relapse. Development of cushingoid syndrome and growth retardation (height 123 cm, −3 S.D.; weight 22 kg, −2.5 S.D.; normal parental heights) determined endocrinological evaluation which revealed normal IGF I (172 ng/ml n=111551), and basal GH (3.3 μI/ml) with response at stimulation (stimulated GH 125 μI/ml) and delayed bone age of 8,5 years. Functional pituitary evaluation was normal.
Reevaluation by muscular biopsy revealed presence of increased lipid droplets in type 1 muscle fibers suggesting LSM. Carnitine supplementation was started in december 2008 and continued without pause (1 g/day) with progressive clinical improvement and normalization of muscular enzymes.
Absence of GH deficiency justified expectative but the stagnant height after 6 months was an argument for hGH therapy, which was started in October 2008 followed by a satisfactory growth rate.
Reevaluation in December 2011 revealed Tanner pubertal stage IV, growth velocity of 0.7 cm/month, actual height of 147 cm (−2S.D.), delayed bone age of 13 years.
Conclusion: We report a patient with idiopathic short stature and LSM who responded well to hGH therapy and carnitine supplementation. To our knowledge, children with LSM do not usually associate short stature or GH deficiency. Impact of hGH therapy on body composition and muscle structure in LSM cases needs to be further evaluated.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector