Clinical_Rounds_in_Endocrinology_Volume_II_-_Pediatric_Endocrinology

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22. What is osteomalacia?

Osteomalacia is a disorder characterized by defective mineralization of osteoid.

In normal physiology, mineralization of osteoid requires optimal calcium-

phosphate solubility product, alkaline pH (7.6) at mineralization site, and pres-

ence of alkaline phosphatase (which suppresses the inhibitors of mineralization).

Therefore, abnormalities in mineral homeostasis, presence of acidic pH (e.g.,

chronic kidney disease), and hypophosphatasia result in osteomalacia.

Growth plate zones

Reserve zone

Changes in

chondrocytes

Proliferative zone

Maturation and

hypertrophy zone

Calcified matrix

zone

Metaphysis

Zone of

Ossification

Primary

spongiosa

Cell Death

Matrix

Calcification

Matrix

production

Mitosis

Secondary

spongiosa

Fig. 5.8 Different zones of growth plate

5 Rickets–Osteomalacia