Vitamin D Intoxication: Too Much of a Good Thing!

correspondence

Indian Pediatr 2013;50: 429-430

	Vitamin D Intoxication: Too Much of a Good Thing!
Meenakshi Bothra and Vandana Jain Division of Pediatric Endocrinology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India, Email: [email protected]
Vitamin D deficiency is common among Indian children [1]. The recommended therapy for vitamin D deficiency rickets is 1,00,000–6,00,000 IU [2]. The increasing awareness about beneficial effects of vitamin D has led to an increase in its prescription [3]. However, one needs to be cautious while prescribing vitamin D, as overdose can lead to severe hypercalcemia. We present the case of an 18-month-old girl, referred with lethargy and vomiting for 10 days, and polyuria for 5 days. She was noticed to have bowing of legs 3 months ago, and diagnosed to have rickets. Her 25-hydroxy D₃ level was 37.5 nmol/L (normal: 75-250 nmol/L). She was started on oral calcium and cholecalciferol 60,000 IU per day, for 6 weeks. In follow-up, the prescription was repeated for another 6 weeks. Meanwhile, the parents consulted another practitioner for the ‘persistent’ bowing, who administered 6 lakh IU vitamin D₃ intramuscularly. The cumulative dose of vitamin D received by her was nearly ten times the therapeutic dose. At presentation, the child was irritable and dehydrated, with BP of 136/94. Serum ionized calcium was 2.83 mmol/L, total calcium 20 mg/dL (normal: 9-11 mg/dL), phosphate 2.63 mg/dL (normal 2.5-4.5 mg/dL), alkaline phosphatase 513 IU/ L (normal 240-840 IU/L), 25-hydroxy D₃ > 3500 nmol/L and parathormone level 23.48 pg/mL. Renal and liver function tests were normal. Urinary calcium/creatinine ratio was 2 (normal <0.2). Ultrasonography of kidneys and CECT brain was normal. Wrist skiagram showed healed rickets. She was started on intravenous fluids (1.5 times maintenance), furosemide and hydrocortisone. Injection Calcitonin was added on 2nd day, in view of persistent hypercalcemia. Ionized calcium fell to1.56 mmol/L initially, followed by rebound increase 48 hours later. For control of hypertension, child required amlodipine and enalapril. Child was discharged after 12 days with serum calcium 13 mg/dl and BP 106/70, on tapering doses of oral prednisolone, furosemide and anti-hypertensives. Furosemide and enalapril were stopped after 3 weeks, whereas amlodipine was continued for 6 months in view of persistent hypertension. The serial serum Calcium was 10.5, 10.8 and 10.6 mg/dL, phosphate was 2.4, 5.1 and 5.6 mg/ dL, 25-hydroxy D3 was 3446, 3484 and 1785 nmol/L, and Parathormone was 16, 14.9 and 25 pg/mL at 2, 4 and 12 weeks after discharge. Ultrasonography at 3 and 6 months did not reveal nephrocalcinosis. The manifestations of vitamin D intoxication are related to hypercalcemia, and require prompt treatment. Since vitamin D is stored in fatty tissues, the toxicity may last for up to 6-8 months. Calcium induced hypercatecholaminemia, and direct effect on vascular smooth muscle are responsible for hypertension [4]. Treatment modalities include diet with low calcium and phosphorus, hydration, loop diuretics, glucocorticoids, calcitonin and bisphosphonates [5]. Hemodialysis is useful in life Threatening hypercalcemia. Before starting vitamin D for children with rickets, parents should be asked about previous vitamin D administration. In case of doubt regarding either the diagnosis of vitamin D deficiency, or previous intake of vitamin D, it is prudent to check 25-hydroxy vitamin D levels. Parents should also be counseled that bowing of legs would take time to resolve and does not require repeated courses of vitamin D. Vitamin D needs to be used with caution, and only when indicated, to avoid adverse effects. References 1. Jain V, Gupta N, Kalaivani M, Jain A, Sinha A, Agarwal R. Vitamin D deficiency in healthy breastfed term infants at 3 months and their mothers in India: Seasonal variation and determinants. Indian J Med Res. 2011;133:267-73. 2. Misra M, Pacaud D, Petryk A, Collett-Solberg PF, Kappy M. Vitamin D deficiency in children and its management: Review of current pediatrics knowledge and recommendations. Pediatrics. 2008;122;398-417. 3. Autier P, Gandini S. Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled trials. Arch Intern Med. 2007;167:1730-7. 4. Eiam-Ong S, Eiam-Ong S, Punsin P, Sitprija V, Chaiyabutr N. Acute hypercalcemia-induced hypertension: the roles of calcium channel and alpha-1 adrenergic receptor. J Med Assoc Thai. 2004;87:410-8. 5. Barrueto F, Wang-Flores HH, Howland MA, Hoffman RS, Nelson LS. Acute vitamin D intoxication in a child. Pediatrics. 2005;116:e453–e6.