Bone Health Evaluation in the Child Vulnerable to Fracture
• During childhood, bones go through a unique process of remodeling that is different from any other phase of growth.
— Remodeling is regulated by local cytokines; by circulating hormones, including parathyroid hormone (PTH), 1,25-dihydroxyvitamin D (1,25-OH2-D), insulin-like growth factor 1 (IGF-1); and by calcitonin
— During adolescence, osteoblasts (involved in bone formation) are more active than osteoclasts (involved in bone resorption), leading to net accrual of bone mass.
— Normal development leads to a 90% increase in bone growth over the first 2 decades after birth and to almost half of adult bone mass accrual in adolescence.
• Peak bone mineralization occurs approximately 1 to 1½ years after the peak in height velocity (Figure 43-1).
• Optimal bone health is achieved with proper nutrition, muscle mass development, and load-bearing activities. A number of variables can interfere with the bone remodeling and growth process during childhood (Figure 43-2).
When to Consider Bone Health Workup
• Criteria for when to initiate a bone health workup or refer to a bone health specialist are controversial. Box 43-1 lists some considerations.
• Conditions that affect bone health
— Genetic disorders
■Connective tissue disorders, such as Marfan syndrome, Loeys-Dietz syndrome, and Ehlers-Danlos syndrome
■Glycogen storage diseases
Figure 43-1. A graph of bone mineral accrual in boys and girls. BMC, bone mineral content; PHV, peak height velocity; TB, total bone.
Reproduced from Bailey DA, McKay HA, Mirwald RL, Crocker PRE, Faulkner RA. A six-year longitudinal study of the relationship of physical activity to bone mineral accrual in growing children: The University of Saskatchewan Bone Mineral Accrual Study. J Bone Miner Res. 1999;14(10):1672–1679.
Figure 43-2. Bone health over time. Abbreviation: Vit D, vitamin D.
Reprinted from Heaney RP, Abrams S, Dawson-Hughes B, et al. Peak bone mass. Osteoporos Int. 2000;11(12):985–1009. © 2000, with permission from Springer Nature.
Box 43-1. When to Consider Referral to a Bone Health Specialist or Initiating a Bone Health Workupa
• Atypical fractures (hip, femoral, or vertebral)
• Fractures that occur with minimal trauma or low velocity
• History of multiple fractures (>2)
a Workup includes dual-energy x-ray absorptiometry scan and laboratory studies.
■Menkes disease (ie, kinky hair syndrome)
■Idiopathic juvenile osteoporosis
— Chronic disease and nutritional deficits
■Anorexia, dysphagia, and failure to thrive are examples of conditions that affect nutritional intake of calcium, magnesium, phosphorus, and vitamin D
■Dairy avoidance due to milk allergy or lactose intolerance may also affect nutritional intake
■Conditions causing intestinal inflammation can limit absorption of minerals (eg, celiac disease, inflammatory bowel disease, colitis, cystic fibrosis)
— Autoimmune and endocrine disorders
■Juvenile idiopathic arthritis, systemic lupus erythematosus, and multiple sclerosis
■Hyperthyroidism, specifically, Graves disease
■Glucocorticoid excess (endogenous or iatrogenic)
■Growth hormone deficiency
■Sex steroid deficiency or resistance
■Type 1 diabetes
■Relative energy deficiency in sport (RED-S) (see Chapter 33, Overuse Injuries)
❖ Previously called female athlete triad, RED-S includes male athletes.
❖ Athlete with disordered eating and suppressed gonadotropic hormones. This is exhibited in females as amenorrhea or oligomenorrhea and decreased bone density.
— Neuromuscular conditions
■Cerebral palsy, muscular dystrophies and spinal muscular atrophy, and paraplegia
■Risks increase with the severity of disease.