Physiologic Leg Bowing is not a Physiologic Condition but Instead is Associated with Vitamin D Disorders in Toddlers.

Abstract

When children around 2-year-old show leg bowing without lower-limb radiographic abnormalities for rickets, the leg bowing is classified as "physiologic" genu varum without conducting a blood test. However, it has recently been suggested that toddlers who are diagnosed with physiologic genu varum may in fact have some form of bone metabolic disorder. In this 1:2 case-control study, blood samples were obtained from 33 toddlers with genu varum without radiographic abnormalities for rickets and 66 age- and gender-matched healthy children. Serum alkaline phosphatase (sALP), intact parathyroid hormone (siPTH), 25-hydroxy vitamin D [s25(OH)D], calcium (sCa), and inorganic phosphate (sP) were measured. s25(OH)D of the subjects with genu varum (24.8 ng/ml) were significantly lower than those of the control (33.6 ng/ml) (p < 0.001). The frequency of vitamin D insufficiency/deficiency (< 20 ng/ml) of the subjects with genu varum (39%) was significantly higher than that in the control (14%) (p = 0.004) (odds ratio by vitamin D insufficiency/deficiency: 4.1 [1.5-11.1, p = 0.004]). sCa in subjects with genu varum (10.2 ng/ml) were significantly higher than in control (9.8 ng/ml) (p < 0.001), as were sALP (1057 IU/l) and siPTH (28.4 pg/ml) (740 IU/l and 8.8 pg/ml in control, respectively; p < 0.001). siPTH levels were associated with s25(OH)D levels in subjects with genu varum (r = - 0.57, p < 0.001), while no association was observed in the control (r = 0.11, p = 0.36). Genu varum without radiographic abnormalities of rickets was associated with both vitamin D and bone-metabolic disorders in toddlers, indicating that physiologic genu varum is not a physiologic condition in toddlers.

• Authors: Yuko Sakamoto, Muneaki Ishijima, Satoshi Nakano, Mitsuyoshi Suzuki, Lizu Liu, Akifumi Tokita, Sung-Gon Kim, Toshiaki Shimizu, Kazuo Kaneko, Masahiko Nozawa
• Journal: Calcified tissue international (Calcif Tissue Int) Vol. 106 Issue 2 Pg. 95-103 (02 2020) ISSN: 1432-0827 [Electronic] United States
• PMID: 31595325 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Parathyroid Hormone
• Phosphates
• Vitamin D
• 25-hydroxyvitamin D
• Alkaline Phosphatase
• Calcium

Topics

• Adolescent
• Adult
• Age Factors
• Alkaline Phosphatase (blood)
• Bone Diseases, Metabolic (blood, complications, epidemiology)
• Calcium (blood)
• Case-Control Studies
• Child
• Child Development (physiology)
• Child, Preschool
• Female
• Genu Varum (blood, epidemiology, etiology)
• Humans
• Japan (epidemiology)
• Male
• Parathyroid Hormone (blood)
• Phosphates (blood)
• Prevalence
• Vitamin D (analogs & derivatives, blood)
• Vitamin D Deficiency (blood, complications, epidemiology)
• Young Adult