Clinical Characteristics of Nutritional Rickets in Korean Infants

Kim, Jun Woo; Han, Heon Seok

Abstract

PURPOSE
The prevalence of nutritional rickets in developed countries appears to be rising. We studied cases of recently diagnosed nutritional rickets in Korean infants to investigate the clinical characteristics of this condition.
METHODS
We studied the medical records of 15 patients (10.5 +/- 10.5 mo) with clinical and subclinical nutritional rickets diagnosed between January 2007 and June 2009 and grouped them according to their clinical presentation. Group I (n = 6, 4.5 +/- 5.2 mo) included patients who were asymptomatic and had increased levels of serum alkaline phosphatase (ALP); group II (n = 5, 21.7 +/- 10.1 mo), patients with skeletal abnormalities; and group III (n = 4, 5.7 +/- 4.5 mo), patients with hypocalcemic seizure. These groups were compared for age and serum levels of calcium, phosphorus, ALP, 25-hydroxy vitamin D (25OHD), and parathyroid hormone (PTH).
RESULTS
The serum 25OHD level was 16.5 +/- 9.9 ng/mL. All but 2 patients were being breast-fed or had been breast-fed for more than 6 months. Infants in group I were relatively young, with 2 small for gestational age (SGA) infants, and showed the highest serum levels of ALP with low serum levels of 25OHD (15.3 +/- 6.2 ng/mL), but mild radiologic changes. Group II infants (including 4 with bow leg and 1 with short stature) were significantly older (P = 0.018) with relatively higher levels of 25OHD (23.0 +/- 11.6 ng/mL) but worse radiologic findings as compared to other groups. Group III infants were relatively young including 2 SGA and had the lowest 25OHD levels (10.3 +/- 9.4 ng/mL) and significant hypocalcemia (P = 0.016, 5.7 +/- 4.5 mg/dL), but mild radiologic changes. The fact that group I and III were very young implies that not only were these infants supplied with inadequate amounts of vitamin D, but many began life with small stores of vitamin D as a result of maternal vitamin D deficiency.
CONCLUSION
Nutritional rickets manifested in 3 different clinical forms, and vitamin D should be supplemented in breast-feeding infants as well as pregnant women.