Metabolic control and growth during exclusive growth hormone treatment in X-linked hypophosphatemic rickets.
BACKGROUND
GH may improve phosphate balance and height in X-linked hypophosphatemic rickets (XLH). This study evaluated the impact of exclusive rhGH therapy on phosphate homeostasis and growth.


METHODS
Ten children (median age 12.2 years) with XLH were included in a 12-month trial with GH. Conventional treatment was discontinued 1 month prior GH (0.033 mg/kg/day); 1alpha-hydroxyvitamin D was added at 6 months and oral phosphate at 12 months, when GH was discontinued. Patients were followed 1-3 monthly until 18 months for clinical, biochemical and radiographic parameters.


RESULTS
Serum phosphate Z-score increased significantly from baseline at 6 months (p = 0.005) and 9 months (p = 0.009) but returned to baseline by 12 months. Serum 1,25-dihydroxyvitamin D also increased significantly. Parathyroid function normalized. The median height Z-score was -2.2 (-2.7 to +0.4) at GH onset and -1.7 (-2.3 to +0.3) at 12 months. One patient showed a significant increase in radiographic rickets activity and 3 patients aggravation of lower limb deformity; the others showed no changes or improvement in these parameters.


CONCLUSIONS
GH treatment improved serum phosphate and 1,25-dihydroxyvitamin D, normalized parathyroid function and improved longitudinal growth in XLH. It may however aggravate pre-existing skeletal deformities.
Makitie
Outi
O
Hospital for Children and Adolescents, Pediatric Endocrinology and Metabolic Bone Clinic, Helsinki University Hospital, Helsinki, Finland. outi.makitie@helsinki.fi
Toiviainen-Salo
Sanna
S
Marttinen
Eino
E
Kaitila
Ilkka
I
Sochett
Etienne
E
Sipila
Ilkka
I
D000293:Adolescent; D001827:Body Height / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D001846:Bone Development / Q000187:drug effects; D001842:Bone and Bones / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D053098:Familial Hypophosphatemic Rickets / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism*; D005260:Female; D040181:Genetic Diseases, X-Linked; D013006:Growth Hormone / Q000627:therapeutic use*; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D006887:Hydroxycholecalciferols / Q000627:therapeutic use; D006961:Hyperparathyroidism / Q000209:etiology / Q000517:prevention & control; D008297:Male; D010280:Parathyroid Glands / Q000187:drug effects / Q000502:physiology; D010710:Phosphates / Q000378:metabolism* / Q000627:therapeutic use; D011859:Radiography; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
D050071:Bone Density Conservation Agents; D006887:Hydroxycholecalciferols; D010710:Phosphates; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; D013006:Growth Hormone; C008088:alfacalcidol