Eight cases of incidentally diagnosed as subclinical rickets

Abstract

Purpose : Vitamin D plays a key role in bone mineralization of the skeleton and vitamin D deficiency can lead to rickets. It is well known that vitamin D deficiency is common in breast fed infants. Of these patients, clinically, some have no signs of rickets, but laboratory and radiographic findings are diagnostic for vitamin D deficiency rickets (subclinical vitamin D deficiency rickets). The purpose of this study is to clarify current causes and ways to prevent this disease. Methods : We reviewed the clinical and laboratory characteristics of children who were incidentally diagnosed as subclinical rickets during treatment of other disease such as pneumonia, gastroenteritis, urinary tract infection at Eulji Hospital, Seoul, Korea from March, 2003 to July 2007. Results : Eight patients (six boys and two girls) were diagnosed with subclinical vitamin D deficiency rickets. The mean age of the patients was 12.6±5.8 months, and they were diagnosed from January to July. The associated diseases were pneumonia, urinary tract infection, acute gastroenteritis, and iron deficiency anemia. All patients were breast-fed. Two showed growth failure. The mean serum alkaline phosphatase was 1995.8±739.5 IU/L, the mean calcium count was 9.5±0.6 mg/ dL, and the mean phosphorus content was 3.6±1.5 mg/dL mg/dL. The mean intact parathyroid hormone was 214.8±155.9 pg/mL (reference range, 9-65), the mean 1,25-dihydroxyvitamin D was 82.4±49.3 pg/mL (reference range, 2070), and the mean 25-hydroxyvitamin D was 29.6±10.6 ng/mL (reference range, 1030). A radiographic examination showed cupping, fraying, and flaring of metaphyses in all patients. Six patients were administered calcitriol (400 IU/day) for three months. A consequent radiographic and laboratory examination showed improvement. The first two patients were initially diagnosed with metaphyseal dysplasia, without the detection of vitamin D deficiency and they spontaneously improved without vitamin D supplements. However, two years later, they showed mild scoliosis and metaphyseal dysplasia, respectively. Conclusion : Breast-feeding without supplementation involves high risk of vitamin D deficiency. Some infants may also develop rickets; therefore, such groups should be considered for vitamin D supplementation.