Background: Hereditary vitamin D-resistant rickets (HVDRR) is a rare disease caused by mutations in vitamin d receptor (VDR). Patients with HVDRR are usually treated with intravenous calcium (i.v.-Ca) therapy via a central catheter. However, central catheter-related complications can cause important morbidity. In this report, we described four patients with HVDRR from different families. In three of these cases we used a novel therapeutic regime of intermittent IV-Ca therapy via peripheral vein.
Cases: Four unrelated patients born to consanguineous parents, presented with inability to walk, leg deformities, and alopecia totalis. Diagnosis of HVDRR was established based on clinical and laboratory features (Table 1) and high 1.25 (OH)2 D levels. High dose oral calcium and calcitriol treatment failed to achieve significant improvement. Intermittent i.v.-Ca treatment (25 times per week) was begun in four patients by peripheric route. In one patient, parents preferred central venous route and hence treated that way. No complications such as infection, extravasation of Ca or arrhythmias were detected with peripheral infusion. After normalization of PTH and ALP (saturation of bone) with i.v.-Ca (which varied 122 months), physiological doses of oral Ca (200400 mg/kg per day) and calcitiriol (0.5 μg/kg per day) were sufficient to maintain PTH levels within the normal ranges in all patients. Molecular studies showed that patient #1 and #2 had a homozygous Q152X mutation. Patient#3 had a novel homozygous mutation at intron 5, IVS8 as-2 A>G, which effects the splice acceptor site. Patient #4 had a novel homozygous c.67insG mutation, which causes a frameshift and result in a premature stop (p.Ile23Asp fsX20).
|Age of 1st symptoms (months)-Sex||8 (F)||Nk (M)||6 (F)||12 (M)|
|Age of presentation (years)||4.3||9.8||2.7||1.5|
|Ca mg/dl (mmol/l)||8.2||7.5||8.6||8.2|
|PO4 mg/dl (mmol/l)||2.5||3.4||2.9||2.2|
|Age at initiation of IV Ca (years)||5.2||9.8||4.8||1.9|
|Route of i.v. therapy||periphery||periphery||periphery||Central|
|i.v. Ca dose (mg/kg/week)||18||90||60||18|
|Duration of i.v. Ca therapy (months)||10||1||22||10|
|VDR mutation||Q152X||Q152X||IVS8 as-2 A>G||p.Ile23Asp fsX20|
Conclusion: Here we reported four HVDRR patients with three different mutations and, their successful treatment with intermittent intravenous Ca therapy, via either peripheric or central route. Peripheral i.v.-Ca treatment seemed to be an effective alternative treatment mode with dramatic clinical benefit and a minimal cost in patients with HVDRR.
01 Oct 2015 - 03 Oct 2015