Alkaline phosphatase in pediatric patients with genu varum caused by vitamin D-deficient rickets.

An elevated serum alkaline phosphatase (ALP) level is one of the markers for the presence of rickets in children, but it is also associated with bone formation. However, its role in diagnosing genu varum in pediatric patients with vitamin D-deficient rickets is still unknown. To clarify the role of the serum ALP level in assessing the severity of genu varum, we retrospectively investigated this issue statistically using data on rickets such as serum intact parathyroid hormone (iPTH), 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, ALP, the level of creatinine as the percentage of the median according to age (%Cr), and the metaphyseal diaphyseal angle (MDA) in the lower extremities as an index of the severity of genu varum. A multiple regression analysis revealed that log ALP and %Cr values were negatively associated with MDA values. The former association was also confirmed by a linear mixed model, while iPTH was positively associated with MDA by path model analysis. To elucidate the association of ALP with MDA in the presence of iPTH, we investigated three-dimensional figures by neural network analysis. This indicated the presence of a biphasic association of ALP with MDA: the first phase increases while the second decreases MDA. The latter phenomenon is considered to be associated with the increase in bone formation due to the mechanical stress loaded on the lower extremities. These findings are important and informative for pediatricians to understand the significance of the serum ALP level in pediatric patients with genu varum caused by vitamin D deficiency.

[Updates on rickets and osteomalacia: guidelines for diagnosis of rickets and osteomalacia].

Rickets and osteomalacia are disorders of calcification characterized by defects of bone and cartilage mineralization during growth, and bone mineralization in adults, respectively. The specific x-ray findings including a cupping, flaring, and fraying of metaphysis and the elevation of the level of serum alkaline phosphatase are essential for the diagnosis of rickets. In addition, hypophosphatemia, hypocalcemia, and some symptoms including born deformity, spinal curvature, craniotabes, enlargement of the anterior fontanel, rachitic rosary, and joint swelling are also important. Clinicians need to consider the different normal ranges of the levels of serum alkaline phosphatase and phosphate depending on their patient's age when they diagnose their childhood patients. In contrast, the radiographic diagnosis of osteomalacia is difficult. The hypophosphatemia or hypocalcemia and the elevation of serum bone alkaline phosphatase are essential for the diagnosis of osteomalacia. Moreover, some clinical features including muscle weakness and bone pain, the decrease of bone density, and the finding of multiple uptake in bone scintigraphy or of the pseudofracture in bone x-ray study are also important. It is very useful for the differential diagnosis to measure the serum levels of 25-hydroxy vitamin D and fibroblast growth factor 23.

[Suspected case of pseudohypoparathyroidism type II].

We experienced a suspected case of pseudohypoparathyroidism type II. The patient came to our emergency room with no thermal convulsion. The Ellsworth-Howard test was applied to the patient to determine the type of PHP.