Related Experiment Videos
Unique form of rickets with low serum 25-hydroxyvitamin D in two normally nourished children
T Asami1, T Kawasaki, M Uchiyama
1Department of Pediatrics, School of Medicine, Niigata University, Japan.
Insights
This study describes a unique form of vitamin D-resistant rickets in two boys with normal growth. Their condition showed low 25-hydroxyvitamin D (25-OH-D) but normal 1,25-dihydroxyvitamin D (1,25-(OH)2-D) levels.
Area of Science:
- Pediatric Endocrinology
- Nutritional Rickets
Background:
- Rickets is a condition causing bone softening in children, often due to vitamin D deficiency.
- Vitamin D-resistant rickets presents challenges in treatment and diagnosis.
- Understanding novel forms of rickets is crucial for effective pediatric care.
Observation:
- Two boys, aged 2 years and 15 months, presented with severe lower extremity bowing and costochondral junction bulging.
- Both children exhibited normal growth parameters, exceeding the 50th and 97th percentiles for height and weight.
- Radiographic examination revealed changes consistent with vitamin D-resistant rickets.
Findings:
- Elevated serum alkaline phosphatase with normal serum calcium and phosphate levels were noted.
- Key biochemical findings included persistently low serum 25-hydroxyvitamin D (25-OH-D) and normal 1,25-dihydroxyvitamin D (1,25-(OH)2-D).
- No primary nutritional deficiencies or other causes for rickets were identified.
Implications:
- Treatment with 1 alpha-(OH)-D3 or high-dose vitamin D2 improved clinical and radiographic outcomes.
- The low 25-OH-D levels only normalized with massive vitamin D2 therapy.
- These cases represent a distinct type of rickets not previously classified, highlighting the complexity of vitamin D metabolism disorders.
Abstract:
We present an unusual type of rickets involving two children: a 2 year old boy and a 15 month old boy, who presented with marked bowing of the lower extremities and bulging of costochondral junctions. Both children had normal growth, with their height and body weight greater than the 50th and 97th percentile for age. Roentgenograms of their extremities showed the typical changes of vitamin D refractory rickets. Serum alkaline phosphatase levels were elevated and serum levels of calcium and phosphate were both within the normal range. No primary cause for the rickets, including nutritional deficiencies, was found in the two patients. Characteristic findings were persistently low serum 25-hydroxyvitamin D (25-OH-D) and normal 1,25-dihydroxyvitamin D (1,25-(OH)2-D). Improvements in clinical and X-ray findings were observed after either oral administration of 1 alpha-(OH)-D3 (9-15 micrograms per day) or massive vitamin D2 therapy (600,000 IU single injection). The low serum levels of 25-OH-D did not increase unless massive vitamin D2 therapy was also given. These two cases represent a unique form of rickets that does not meet the criteria for any type of previously known rickets.