Bone Health Evaluation in the Child Vulnerable to Fracture

CHAPTER 43

Bone Health Evaluation in the Child Vulnerable to Fracture

Introduction

• 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

■Fibrous dysplasia

■Gaucher disease

■Galactosemia

■Glycogen storage diseases

■Homocystinuria

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.

Box 43-1. When to Consider Referral to a Bone Health Specialist or Initiating a Bone Health Workup^a

• 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)

■Osteogenesis imperfecta

■Turner 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

■Hyperparathyroidism

■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.

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