THE COMBINED USE OF INTRAVENOUS AND ORAL CALCIUM FOR THE TREATMENT OFVITAMIN-D-DEPENDENT RICKETS TYPE-II (VDDRII)

OBJECTIVE Some patients with rickets are resistant to vitamin D and it s analogues; we therefore assessed whether or not normal mineralizatio n could be achieved in the absence of an intact 1,25(OH)2D3 receptor-e ffector system, by the use of intravenous high dose calcium infusion, followed by high dose oral calcium. DESIGN We studied two patients wit h vitamin D dependent rickets type II and with absent responses to eit her high dose calcitriol or to oral calcium alone. Daily infusions equ ivalent to up to 1.4 g elemental calcium supplemented with oral phosph ate were given for a period of 3.5 months for the elder sister and 2 m onths in the younger brother. Both patients were then treated by weekl y calcium infusions for 5 months, followed by maintenance on oral calc ium equivalent to up to 6 g elemental calcium per day. PATIENTs Two si blings of consanguineous parents, a girl aged 28 months and a boy aged 10 months with vitamin D dependent rickets type II. MEASUREMENTS Meas urements of serum and urine calcium, phosphate and serum alkaline phos phatase were obtained before, during and after the calcium infusions.T wenty-four-hour urinary minerals, electrolytes, creatinine clearance, serum PTH and vitamin D metabolites were measured prior to calcium inf usion, then repeated at 2-monthly intervals. Glomerular filtration rat e, kidney ultrasound and CT scan were done at 6-monthly intervals. A s calp biopsy was done at the end of i.v. calcium treatment. RESULTS The daily infusions of calcium supplemented with oral phosphate resulted in biochemical responses with normalization of calcium and phosphate i n 3-5 days, and of alkaline phosphatase and PTH in 1.5-2 months. Radio logical evidence of healing was seen in 42 days. A total of 3.5 months of daily calcium infusion in the elder sister and 2 months in the you nger brother resulted in complete healing biochemically and radiologic ally, with improvement in height. The patients are under current follo w-up, with no evidence of nephrocalcinosis or deterioration of glomeru lar filtration rate. CONCLUSIONS (a) The use of intravenous high dose calcium infusions followed by high dose oral calcium is an effective m ethod of treatment of vitamin D dependent rickets type II. (b) The tre atment was more effective since it was started early in the course of the disease and led to early healing and better growth with prevention of bone deformities. (c) Early treatment may also lead to improvement in alopecia, the mechanism for which needs to be elucidated.