Rickets in early infancy is mostly due to maternal vitamin D deficiency. Infants in this period do not present with typical biochemical and radiologic features and are difficult to diagnose. In this study, it was aimed to evaluate the characteristic features of 42 cases diagnosed as early rickets and to stress hyperphosphatemia at admission. Risk factors for vitamin D deficiency, clinical and biochemical characteristics at admission and parathyroid hormone (PTH) responses of 42 cases (27 boys, 15 girls), who were diagnosed as rickets in the first three months of life, were evaluated cross-sectionally. Mean age of the infants was 60 ± 19 (range: 32 to 112) days. Thirty-three cases (78.7%) presented with convulsion, while seven infants (16.7%) were admitted with respiratory symptoms. The serum 25-OHD levels, which could be measured in 29 infants and 15 mothers, were very low. Though all infants’ serum calcium levels were low, only 26 infants (68%) presented with secondary hyperparathyroidism. Fourteen patients (35%) had high serum phosphorus levels at diagnosis. Seventy-nine percent of all mothers covered their heads outside the home, did not work and spent most of their time indoors. None of the mothers were reported as having used any vitamin D preparations during pregnancy and none of the babies was receiving vitamin D supplement. Infants of mothers at risk for vitamin D deficiency should receive vitamin D support, otherwise they present with symptoms of vitamin D deficiency in the first three months of life. Although hypocalcemia is prominent in these babies, serum PTH does not reach expected levels. Because of the immaturity of the regulating factors of PTH and serum calcium, these infants often present with hypocalcemia due to the failure of progression of disease from stage 1 to stage 2. Therefore, serum phosphorus levels may be high at admission. Because maternal vitamin D deficiency is frequently observed in our country, hypocalcemia in early infancy should usually alert the physician to deficency of vitamin D.

Keywords: Maternal vitamin D deficiency, rickets, hypocalcemia, early infancy, hyperphosphatemia, maternal D vitamini yetersizliği, rikets, hipokalsemi, erken bebeklik dönemi, hiperfosfatemi