Rickets in the wrist. A 3-year-old boy who was an extremely picky eater and had a cognitive delay. He always stayed at home and rarely played outside. Anteroposterior radiograph of the left wrist showed concave deformity of the growth plate of the ulna (cupping: arrowheads) and an indistinct metaphyseal margin (fraying: arrows) in the radius and ulna. His activated vitamin D level (<5 pg ml−1) was lower than the paediatric normal range (20–70 pg ml−1).