M Vierge1, S Laborie2, A Bertholet-Thomas3, M-C Carlier4, J-C Picaud5, O Claris6, J Bacchetta7. 1. Centre de référence des maladies rénales rares, hôpital Femme-Mère-Enfant, 59, boulevard Pinel, 69677 Bron, France. Electronic address: melodie.vierge@ap-hm.fr. 2. Service de néonatologie, hôpital Femme-Mère-Enfant, 69500 Bron, France. 3. Centre de référence des maladies rénales rares, hôpital Femme-Mère-Enfant, 59, boulevard Pinel, 69677 Bron, France. 4. Département de biologie, centre hospitalier Lyon-Sud, 69495 Pierre-Bénite, France. 5. Service de néonatologie, hôpital de la Croix-Rousse, 69004 Lyon, France; Université Claude-Bernard-Lyon 1, 69008 Lyon, France. 6. Service de néonatologie, hôpital Femme-Mère-Enfant, 69500 Bron, France; Université Claude-Bernard-Lyon 1, 69008 Lyon, France. 7. Centre de référence des maladies rénales rares, hôpital Femme-Mère-Enfant, 59, boulevard Pinel, 69677 Bron, France; Université Claude-Bernard-Lyon 1, 69008 Lyon, France.
Abstract
INTRODUCTION: Preterm neonates are particularly at risk of vitamin D (25-D) deficiency. To prevent rickets and osteopenia in this population, international guidelines vary between 800 and 1000IU per day of vitamin D in Europe and recommend 400IU per day in the USA. Target levels of circulating 25-D are not well identified, with the lower target level 50-75nmol/L and the upper target level probably 120nmol/L. METHODS: Between 2013 and 2015, 16 premature infants (born<35WG) were referred to pediatric nephrology clinics because of symptoms secondary to 25-D overdose during the neonatal period. Clinical and biological data were retrospectively reviewed to better define this population. The results are presented as the median (range). RESULTS: Gestational age was 27 (24-35)WG with a birth weight of 810 (560-2120)g. Nephrocalcinosis was the initial symptom in 37% of cases, hypercalcemia in 44%, and hypercalciuria in 19%. Daily vitamin D doses were 333 (35-676)IU. Age and body weight at initial symptom were 36.6 (27.6-47.6)WG and 2300 (640-3760)g, respectively. The 25-D level at the time of the first dosage was 210 (119-350)nmol/L and the 1-25 vitamin D level was 370 (245-718)pmol/L (local normal values for age<240). During follow-up, 12 patients displayed nephrocalcinosis, ten hypercalciuria, and three hypercalcemia. The 25-D level normalized in ten patients within 10 (3-32)months after vitamin D withdrawal. Nephrocalcinosis improved in ten of 12 patients, within 12 (3-30)months. Vitamin D could be readministered in ten patients. When searched (n=3), no CYP24A1 mutation was identified in two patients, but was identified in the heterozygous state in one. CONCLUSION: A 25-D overdose should be systematically ruled out in the presence of nephrocalcinosis, hypercalcemia, and/or hypercalciuria during infancy in children born preterm. Studies are required to assess the exact frequency of 25-D deficiency and overdose in this population, as well as to evaluate the potential deleterious effects of this imbalance on bone, kidney, and brain development.
INTRODUCTION: Preterm neonates are particularly at risk of vitamin D (25-D) deficiency. To prevent rickets and osteopenia in this population, international guidelines vary between 800 and 1000IU per day of vitamin D in Europe and recommend 400IU per day in the USA. Target levels of circulating 25-D are not well identified, with the lower target level 50-75nmol/L and the upper target level probably 120nmol/L. METHODS: Between 2013 and 2015, 16 premature infants (born<35WG) were referred to pediatric nephrology clinics because of symptoms secondary to 25-Doverdose during the neonatal period. Clinical and biological data were retrospectively reviewed to better define this population. The results are presented as the median (range). RESULTS: Gestational age was 27 (24-35)WG with a birth weight of 810 (560-2120)g. Nephrocalcinosis was the initial symptom in 37% of cases, hypercalcemia in 44%, and hypercalciuria in 19%. Daily vitamin D doses were 333 (35-676)IU. Age and body weight at initial symptom were 36.6 (27.6-47.6)WG and 2300 (640-3760)g, respectively. The 25-D level at the time of the first dosage was 210 (119-350)nmol/L and the 1-25 vitamin D level was 370 (245-718)pmol/L (local normal values for age<240). During follow-up, 12 patients displayed nephrocalcinosis, ten hypercalciuria, and three hypercalcemia. The 25-D level normalized in ten patients within 10 (3-32)months after vitamin D withdrawal. Nephrocalcinosis improved in ten of 12 patients, within 12 (3-30)months. Vitamin D could be readministered in ten patients. When searched (n=3), no CYP24A1 mutation was identified in two patients, but was identified in the heterozygous state in one. CONCLUSION: A 25-Doverdose should be systematically ruled out in the presence of nephrocalcinosis, hypercalcemia, and/or hypercalciuria during infancy in children born preterm. Studies are required to assess the exact frequency of 25-Ddeficiency and overdose in this population, as well as to evaluate the potential deleterious effects of this imbalance on bone, kidney, and brain development.